Engine runs too hot

[rainer]

Hello. I kindly ask for your opinion what might be wrong and how you found a solution for that.
Please notice that I use metric measurements (Millimeters, km/h, °C) and no imperial measurements, because I am from Europe.

I own a 1916 Touring, almost original (radiator, engine, no water-pump, ...).

What I permanently have is troubles with cooling at higher environmental temperatures.
While my Lizzy runs fine and has no real issues below 24°C,
when environmental temperature exceeds 25~30°C, the engine reaches the upper border of the motometer's hole within short time, followed by random (seldom) bucking and false ignitions. All this when driving at a speed of approx 45~50 km/h on horizontal street, so I am definitely not racing it. Usually buckling and false ignitions vanish quickly with a little richer mixture (this I immediately do), but temperature stays at that high level. The spark advance lever's tip is at 8:00 o'clock position, so the lever is almost at maximum advance on flat street.

This year Alpenchapter Germany (our local Model T Club) will celebrate its 20th anniversary and we will for sure drive a lot at high summer temperatures, so I am a bit scared on this thermal problem and would like to fix it before.

What can cause this thermal problem my T permanently shows?


What I already did:

• I brought the radiator to a repair workshop because it had a pinhole or bad solder joint at 1-2 tubes at the upper chamber. They could re-solder it, and they also cleaned/descaled the radiator because I pleased them to do so. Afterwards it was noticeably better. This is an original radiator with round copper tubes and brass.
• I drained the radiator from time to time to get out the mud. Actually there wasn't much dirt inside at all, a little bit at the beginning, then clear coolant. (I use a mix of 1/3 antifreeze, primarily to prevent corrosion of engine block). This was a mess when I bought the Lizzy, always a lot of dirt came out, so I think the collection of decades old dirt is out now.
• I tried several settings of mix-richness on carburetor and found the sweet spot where the engine is running best. -> At temperatures of 20~25°C
• Spark-Plugs look good
• I verified the timer adjustment. I use a roller timer. Its lever is 65mm from center of the screw to its left, when spark-advance is fully up (latest ignition). When I pull the lever down 25mm and try to hand-crank, the engine already starts to kick back, while it does not with lever fully-up.. So I am pretty sure the adjustment is correct.

My T has a radiator fan which also is from that time. It is the one with a thin "neck" between its pulley and blades-hub (where blades are riveted on).

View on fan blades from a flat angle

If you wonder about this thumb nuts on radiator mesh... They hold a "Ford" Script on front of the radiator.
I also had to fix the fan by opening the hollow pulley from rear side and gluing in a turned brass insert using Epoxy. This is an invisible repair, allowing me to insert needle bearings. This was necessary because the former owner carelessly drilled up the center hole below the pulley and pressed in two needle bearings from rear, ignoring that the remaining wall became less than 0.5mm thin. So this wall broke off and there was no bearing below the pulley any more. The thin neck had to take all belt force and was also worn out heavily therefore. The new bearings work well and the fan is running smoothly again. They sit inside the pulley (all length of pulley) while the thin neck has no touch to the bolt any more.

View on fan from steeper angle

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From my technical understanding the car has a problem with radiation. The radiator will for almost sure be ok, but it appears to have a little bit too low efficiency at higher environmental temperatures. I think a water pump will not help much. It possibly increases the circulation, but it will not increase the radiation itself. Also I dislike to add one because it reduces the originality. I think the best solution for increasing heat radiation is increasing the air flow through the radiator.

Please have a look on my pictures. This pictures are made before my change I did yesterday. Please have a close look on the fan, and the angle of fan blades.
For my opinion the fan blades are in a relatively flat angle, but I cannot compare with others, so I decided to ask here.
Yesterday I took out the fan and carefully bent the blades to a steeper angle close to the hub (on first 25mm). So when placing the fan with its front onto the workbench, the rear edge of the blades is now ~8mm higher. This way I increased the angle of fan blades some (approx 5) degrees, this should increase air flow.

I am very interested in your opinion and suggestions. It would be great if I could solve this problem once and forever. As this car was running almost everywhere in USA, also in lots hotter regions, I cannot believe that this problem cannot easily be solved.

Have a nice 'T'ime.

Rainer.-

[love2T's]

2 thoughts....yes you'll get 50 other answers too!
You say you got "some mud" out of the radiator. Since it sounds like it sat so long with mud drying in it, I'm wondering if ALL the mud is out? How can you tell? I'll tell you.... give it the "4 second test". Basically it's best to remove the radiator but can be done in the car. Remove radiator, obviously it's drained again. Plug up the bottom pipe hole and of course the pet cock drain. Use something that can be easily removed from the bottom pipe connector. I use a rubber pipe cap. Works well. Plug the top hole of the inlet opening. Fill radiator til water comes out the top throat. This is where it helps to have a helper to do the timing with either a stop watch or just carefully watch a wristwatch with a second hand on it. Remove the bottom plug and start counting! If it completely drains in 4 seconds, it's a good radiator.

If it takes like around 6 seconds, it's got "crap in it" but still viable radiator. Much of anything longer than that, and in my opinion, it's shot. Trust me, I've done this many times, finding both good and bad radiators with this method.

Second thought...pull your head off the engine and inspect all the water passageways/holes for being plugged up also.

Hope this helps.

[36mike]

I don't know about the geometry of the spark lever on your 1916, as compared my 1926, but I drive with the lever at 6 oclock. Try some more timing.

Mike

[John.Zibell]

If an old radiator/original, the fins separate from the tubes. You may be in need of a new radiator.

[TXGOAT2]

I normally drive with the spark fully advanced at any speed over about 20 MPH in high. I would remove anything that is in front of the radiator. Under most conditions, a Model T will run cool at speeds over about 12 to 15 MPH with the fan entirely removed, so I doubt that your fan is the problem. I suspect that your radiator is still partially clogged up and that your engine water jacket is also dirty.
I have driven my T for many miles at 40+ MPH in temperatures of 95 F to 105 F with no fan installed and no overheating issues. The commonest cause of overheating in Model Ts is dirt, rust, and scale in the cooling system. Late spark timing is another likely cause.
Dragging brakes or transmission bands can also cause overheating and poor performance. A Model T will perform best when running on magneto, especially at open road speeds.
An excessively lean fuel mixture will contribute to overheating. I adjust the spark advance and fuel mixture as I drive to suit the operating conditions of the moment. Any one of the issues listed above, or any combination of one or more of them, can lead to overheating. High altitude will promote boiling, but should not cause overheating if the car is in good condition.

[TXGOAT2]

Mr. Zibell makes a good point. Many old radiators have developed a condition in which they lose much of their heat dissipation ability, even if they are clean internally. The radiator fins can become thermally isolated from the tubes, which greatly reduces the radiator's effective area.

[rainer]

love2T's,

thanks for your good suggestions.
Possibly "mud" is the wrong name/word Indeed, it suggests something thick and pasty. this is not the case. When I bought the Lizzy, the radiator was filled with water, what happened before, I cannot say. What came out when draining it was rusty looking water with fine grained chalk as I could see inside the hose studs, too (there as hard deposit), but this "dirt" was floating in the drained water. This is meanwhile almost gone so I am pretty sure this came from the engine (former owner) and is meanwhile flushed out. The car might have been unused long time so this had settled down inside engine and became loosened since I started driving it and flushed the radiator 2-3 times.
After 2 years the radiator was maintained (because of minimal leakage of tubes on upper chamber), and hereby it was cleaned out with acid by the radiator company. As mentioned, it was lots better after this maintenance and re-soldering. I didn't drive so much that something could have clogged inside the radiator since then.

Following your first thought: I am pretty sure that this will be less than 4 seconds.
But I will verify it when I remove the lower hose next time to be absolutely sure. Have to pull the car out of my garage to test that, otherwise I cause an indoor water damage in my garage.

My biggest sorrow was that the former owner used some "self-working radiator sealer", but it seems he (luckily) did not. As this stuff hardens in contact with air and clogs fine holes when it comes in touch with air, it would have covered the entire radiator from inside, because there is always air inside the cooling system of a 'T'. Luckily this was not the case.

About your second thought...
I don't have so much experience with behavior of a 'T', but shouldn't this look different? From my understanding this would lead into reduced circulation at some points in the engine. There water may start boiling then, but it would mix with cooler water from other channels to an lower average, no? When I had the engine out for clutch rework, I inspected the engine's radiator studs. They were not so bad, also not the hole in engine block. A thin layer of red-brown chalk, but not more than I would expect. 2 years ago the first freeze plug was leaking (rusted through from inside), also there no unusual deposit of chalk as deep as I could look inside. I also have almost similar compression on all cylinders and spark-plugs look very identical, I think this engine is ok.

Also I am a bit scared about pulling the head. Starts with rusted-in bolts, I have no new gasket, ... from outside the engine looks beautiful, but who knows what is hidden inside. But when I have to pull the head in future, I will for sure verify that.

[AndyClary]

Your problem sounds like the classic old round tube radiator issues. As a couple guys already painted out, as the radiator ages it looses conductivity between the fins and the tubes. While the radiator still works to some extent, once it gets hot it lacks the capacity to cool. Unfortunately you are probably going to have to replace the radiator or recore yours if you can find a core. A water pump may buy you some time but no guarantees.

Andy

[rainer]

TXGOAT2,
thanks for your answer. Hope I calculate everything correctly, my first try to convert everything into imperial.

Is a separation of radiator fins visible? I had a close look (as far as possible, so actually to the second row of tubed from both sides), and it looks good. I could borrow an infrared camera from a friend and inspect the radiator with it. When thermal conduction somewhere exists, the fins should be lots cooler there.

I will give it a try and remove the "Ford" script in front of the radiator. I already mounted it in some distance using washers behind of it and the script is relatively narrow in most parts (mostly not more than 10-15mm wide) so air should easily get directly behind it, but you are right. It still is a barrier in air flow. And it seems this radiator is close to its limits.

From your driving:
When engine is idling, I set the spark lever with long part horizontally. The short part is then pointing to approx at 8:00 position.
When driving at high, I usually set the advance to max, so the short part of the lever points to approx 6:00.

My T also runs cool when I am driving 15~18 MPH. Then the moto-meter settles a 1/4" below the hole.
This weekend I was driving approx 31 MPH at temperature between 85~100 F. Three persons inside, open top, little windspeed. The street had a very decent permanent inclination. The gas-lever was at approx 1/3 down. Here the moto-meter climbed to the upper margin of the hole. The engine started bucking every 4~5 seconds once. Then it made some fail ignitions.
I immediately reduced speed a bit and enriched the gas-mixture. Bucking and false ignitions immediately vanished and I drove the rest at 25 MPH.

Does this indicate something to you?

[John Codman]

If an old radiator/original, the fins separate from the tubes. You may be in need of a new radiator.

I agree. A new radiator solved my heating issue.

[rainer]

Your problem sounds like the classic old round tube radiator issues. As a couple guys already painted out, as the radiator ages it looses conductivity between the fins and the tubes. While the radiator still works to some extent, once it gets hot it lacks the capacity to cool. Unfortunately you are probably going to have to replace the radiator or recore yours if you can find a core. A water pump may buy you some time but no guarantees.

Andy

Hi, Andy.
Yes, it indeed sounds so.

The major problem I see is that a replacement radiator (brass, fitting a 1916) is relatively pricey. Getting a recore within Europe is also not so much cheaper. The workshop that did my re-soldering right below the upper radiator neck (there two tubes were not soldered well and slightly leaking), told me they can insert a new mesh (they name it so, the fins with oval tubes), but you don't want to know what they charge for that... But at least, they can do that, and they rework a lot of oldtimer radiators.

Buying a new radiator is out of scope as long as this interesting president plays his horrible tax-game. This would for sure also double the cost here.

[Jerry VanOoteghem]

I completely agree with the others who suggest that your radiator fins have lost contact with the tubes. You asked earlier if this can be seen. It's usually not obvious to the naked eye, but sometimes you can slide a knife between the fins and gently push a fin up or down to see if it's still attached to the tube, or if it can be moved. The best test, however, is to measure temperatures at the inlet & outlet of the radiator. The temperature drop will indicate the general health of the radiator. If I recall correctly, you would like to see a 30F, (20C), drop, (or more), in temperature at the radiator outlet.

[TXGOAT2]

It sounds like you were running too lean when adjusting the carburetor improved performance. You may have a slight air leak at one of the intake manifold joints, or there may have been a bit of dirt under the metering needle, or the setting may simply have been too lean for the operating conditions.

In the case of a radiator that has lost efficiency and is not internally clogged, what often happens is that over many years, the close contact between the tubes and fins is lost due to vibration, corrosion, and thermal cycling. The very small gap between the tube and fin is usually filled with products of corrosion, and cannot be seen, but it serves as a thermal barrier between the tube and the fin. Cleaning the radiator will have little effect, and it is nearly impossible to re-establish the proper contact between the tubes and fins. The solution is to have the radiator re-cored, or replace it with a new one or a better used one. Good used original radiators are VERY rare.

If the system is internally clogged, many people have had success using a product called "ThermoCure" to remove deposits inside the radiator and engine block.

[Jones in Aiken SC]

As others have noted, either get the radiator recored or get a new radiator. You will never be happy until you do. Trust me, been there done that. A new radiator is pricey but here in the US a recore is almost the cost of a new radiator, that is if you can find an old-timey radiator shop that will do it.

Bite the bullet, and get a recore or a new radiator.

[rainer]

Thank you all for your answers and helpful and valuable information.

I will check the thermal situation with steeper fan blades. Hope this will solve the problem partially. Thanks for the details on temperature drop on radiator, this will also be my next test.

About lose fins... This should be relatively easy to find out by using a infrared camera.

I also think the mixture might have been too lean for higher temperatures, I will do test drives with richer mixture.

Thank you very much again.


Btw., are radiator fins of original radiators only press-fitted to the tubes, or are they soldered on?

[love2T's]

Press fitted. I too was gonna mention the probability of loose fins but got distracted and then didn't want to make my post any longer than it already was

That said...as some suggested...start "easy" and have the radiator "boiled out" by a radiator shop if you have one handy. I had the original round tube radiator on my '26 Fordor repaired for a leaky overflow tube and they boiled it out as normal procedure and it now cools like a brand new radiator.

After that if it doesn't satisfy you continue onward with pulling the head once you obtain a new gasket first. Make sure all the water circulation holes are clean and free. Lastly, be advised you'll wait 6 months for a new radiator as there's only one maker I believe and they're overwhelmed. Of you do buy a new one..get a flat tube radiator.

[John kuehn]

Bottom line is what others have said. A good cooling radiator is a must for a Model T to really drive and enjoy. Radiators can fool you if they look good and especially if it’s an original. Either get it recored or buy a new flat tube.
A poor cooling radiator is first in line to cause cooling issues and next is stopped up water circulation holes in the block and head.
If the head hasent been off your T in recent memory the holes are getting stopped up with rust or stopped up already.
Good luck

[TRDxB2]

I am a advocate of having engine splash pans. Many don't reinstall them after doing some maintenance. I have observed that almost all issues with overheating have them removed. I am not saying that is the cause but they have an intended purpose. Cars in the 50's through the 80's didn't have the equivalent but all modern cars do. The negative pressure in the compartment draws more air through an out of the engine compartment.
I noticed hat yours are missing.

[love2T's]

I am a advocate of having engine splash pans. Many don't reinstall them after doing some maintenance. I have observed that almost all issues with overheating have them removed. I am not saying that is the cause but they have an intended purpose. Cars in the 50's through the 80's didn't have the equivalent but all modern cars do. The negative pressure in the compartment draws more air through an out of the engine compartment.
I noticed hat yours are missing.

To each his own like the water pump issue...but I am NOT. Experienced literally no difference with and without them. So when I used to buy a T that had them...off they went. Just too big of a PIA on many fronts. Except catching tools and parts that get dropped!

[Allan]

With so much stuff jammed under the hoods of modern cars,and with the speeds at which they travel, I can understand the need to consider/design them to have maximum cooling effect/airflow. If this became necessary in the 80's why wasn't it needed earlier. To suggest that it was a consideration way back in the early 1900's is a stretch too far. The use of engine pans on early cars, and the introduction of air cleaners, is more likely a reflection of the road conditions of the time. Mud and dust from unsealed roads were likely targets.

Allan from down under.

[TRDxB2]

With so much stuff jammed under the hoods of modern cars,and with the speeds at which they travel, I can understand the need to consider/design them to have maximum cooling effect/airflow. If this became necessary in the 80's why wasn't it needed earlier. To suggest that it was a consideration way back in the early 1900's is a stretch too far. The use of engine pans on early cars, and the introduction of air cleaners, is more likely a reflection of the road conditions of the time. Mud and dust from unsealed roads were likely targets.

Allan from down under.

Agree that the pans were intended to minimize the dust, mud splash & water spray from the engine compartment. Buy what about the louvers on the hood side panels then? Why were they added and increased in numbers over time. In any case, regardless of the intention for having pans & hood louvers both back then, doesn't it make sense now to use them to assist in a better cooling air flow.

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louvers.jpg (37.24 KiB) Viewed 3265 times

[Mike Silbert]

No one has mentioned that a Model T can run hot by just using too thick of an oil.
I have seen this on several cars before.
What grade oil are you using?

The cooling system can be cleaned with vinegar if it is filled with mud or scale and crud.
Vinegar is cheap and environmentally friendly, until it is put in the radiator.
Refill with 2 gallons of vinegar, top it off with water and go for a drive.
After getting it good and hot and letting it sit flush it out and refill with good coolant.

Your best friend is the hand held laser thermometer.
Measure the radiator inlet, outlet, and the fins and see where the temperature is and where it isn't.
Also make sure the MotoMeter is actually reading correctly.

There are lots of potential causes for overheating:
Radiator
Crusty - Clogged Coolant Passages
Coolant type and Level
Oil Type and level
Spark Timing
Fuel Mixture
Dragging Bands or Bushings
Slipping Low Band
Slipping Clutch
Excess Braking
Misfire
Clogged Exhaust
Leaking Valves
Fan issues - But as long as you are moving you do not need a fan at all
Bad Head Gasket - Or Installed wrong
Bad Temperature Gauge
Bad "Updates" to the car
And I am sure I missed some

[rainer]

With so much stuff jammed under the hoods of modern cars,and with the speeds at which they travel, I can understand the need to consider/design them to have maximum cooling effect/airflow. If this became necessary in the 80's why wasn't it needed earlier. To suggest that it was a consideration way back in the early 1900's is a stretch too far. The use of engine pans on early cars, and the introduction of air cleaners, is more likely a reflection of the road conditions of the time. Mud and dust from unsealed roads were likely targets.

Allan from down under.

Agree that the pans were intended to minimize the dust, mud splash & water spray from the engine compartment. Buy what about the louvers on the hood side panels then? Why were they added and increased in numbers over time. In any case, regardless of the intention for having pans & hood louvers both back then, doesn't it make sense now to use them to assist in a better cooling air flow.

--
louvers.jpg

Well, I see this splash boards from a different perspective.

Yes, they are good for protecting the engine compartment from dirt and mud. That's it.

From airflow (cooling) side I do not agree very much. Yes, in theory they may enhance the air flow. But have a look on this sweet, little louvers. My 1916 has - IIRC - 5~6 of them on each side, and they are relatively small and close to the rear end of engine hood. Now compare their free cross-section with the free cross-section (= full area) of radiator. They are less than 10% of it!
From physical law, the air volume on intake and outlet side must be equal. So - regardless of number and size of louvers - they cannot take all the air needed to take away the generated heat.
Another fact is the relatively precise fit of the firewall. 5cm (2") around the Hogshead is not really much (but better than all louvers in total.
So I am inclined to not see the splash-boards as bearing a positive thermal solution. Even worse. If you have low air flow because of tailwind, hot air will be enclosed in the engine compartment lots more than without splash-boards (here some air can swirl in from bottom side and help lowering the temperature around the engine.
Yes, if they only cover the opening between cylinder 3 and radiator, you may gain a little more air flow (because then you have enough cross-section in rear for air-out), but at moderate speed, when driving a long slope, this will be relative... you are slower and run the engine on high power (low air flow + much heat).

I would say splash-boards will have not much effect in cooling, as others stated, too.

[rainer]

No one has mentioned that a Model T can run hot by just using too thick of an oil.
I have seen this on several cars before.
What grade oil are you using?

The cooling system can be cleaned with vinegar if it is filled with mud or scale and crud.
Vinegar is cheap and environmentally friendly, until it is put in the radiator.
Refill with 2 gallons of vinegar, top it off with water and go for a drive.
After getting it good and hot and letting it sit flush it out and refill with good coolant.

Your best friend is the hand held laser thermometer.
Measure the radiator inlet, outlet, and the fins and see where the temperature is and where it isn't.
Also make sure the MotoMeter is actually reading correctly.

There are lots of potential causes for overheating:
Radiator
Crusty - Clogged Coolant Passages
Coolant type and Level
Oil Type and level
Spark Timing
Fuel Mixture
Dragging Bands or Bushings
Slipping Low Band
Slipping Clutch
Excess Braking
Misfire
Clogged Exhaust
Leaking Valves
Fan issues - But as long as you are moving you do not need a fan at all
Bad Head Gasket - Or Installed wrong
Bad Temperature Gauge
Bad "Updates" to the car
And I am sure I missed some

Mike,
thank you for participating.

Here some answers to your questions:
I use SAE40 unalloyed/natural oil.

The radiator was cleaned 2 years ago (acid, as vinegar is, too) by the radiator workshop when they re-soldered thew upper neck and 2 tubes (where it was leaking). Looking inside from top, it looks very clean, no deposits worth to be mentioned. But it (still) is an original radiator with round tubes, and they are not performing so well as modern ones.

Motometer appears to work properly.

Coolant is 1/3 of antifreeze + 2/3 water. I use it to primarily prevent corrosion, the car is sitting always above +8°C over winter, so no danger of freezing.

What I will do next (thanks to Scott Conger) is:
I will take out the carburetor and check its float, and clean it (when necessary). Scott has impressive knowledge and told me some details I should have a look on (there are different floats, I need the lower one, as an example). He also told me how to verify/adjust the correct level setting.
He also gave me a very good description on how to find the right adjustment of mixture richness. -- Thanks Scott!

Meanwhile I am inclined that the thermal problems come from carburetor (setting, possibly partially clogged or not clean, ...). It is very likely that I am driving with too lean mixture.

[TXGOAT2]

SAE 40 motor oil is twice as heavy as what Ford recommended. It is not suited for use in the Model T engine and transmission. Ford recommended what amounts to modern 20 W motor oil of high quality and good resistance to cold thickening. The best oil available today for the Model T, under most conditions, is a good quality 10W30 oil, either regular or synthetic. In colder weather, a 5W20 or even 0W20 will give good results. I have run my car long distances in very hot weather using 0W20 synthetic oil. Since I don't drive the car in very cold weather, and summer weather is VERY hot here, I use 10W30 full synthetic oil all year. I've driven my car well over 16,000 miles with no mechanical issues what so ever. Ford specifically warned AGAINST using heavy oil in the Model T engine.

[TXGOAT2]

Ford placed a spark timing control and a carburetor main jet control at the driver's fingertips. Learn how to use them correctly, and use them, as needed and when needed.

[J1MGOLDEN]

Those fan blades look dangerously close to the radiator fins.

[Mike Silbert]

40 weight oil is too heavy.
On a fresh rebuild it needs to be 20 weight.
After break in (thousands of miles) 30 can be ok.
On a modern oil the first number (before the W) is winter weight and the second number is summer weight. Summer weight matters more than winter because we rarely drive model T's in super cold weather.

And I am on the engine pans do not help cooling bandwagon. They might possibly hurt a bit but it has always been some other reason to get hot.
Henry installed them to keep out mud, rocks, dirt, and maybe some dust.

I have on several occasions accidentally proven that the fan is not important at moderate to "high" speeds by having my belt fall off while driving and not noticing anything until I opened the hood to turn off the gas.
But the fan hitting the radiator is a very noticable event.

[George House]

Through the years I’ve learned that flat black paint on tubes and fins contribute to heat dissipation. Since Rainer’s brass radiator is ‘original’, might fins and tubes be ‘unpainted’ ? Regardless, I don’t think it’ll make much difference. I believe the carb is being operated too lean or possible intake manifold gland leak.

[rainer]

Thank you for your suggestions and comments.

As George House mentioned, it is very likely that the engine was running too lean, causing too high temperatures in combustion chambers.

This weekend I will take off the carburetor and inspect it. Check the float adjustment (and gas level this way), clean out dirt (if any), ... it is possibly time to do that, I never checked it since I bought the car.
This done, the richness of mixture should be stable in full range (idle … full power), this will make adjustment easier.

About fan blade spacing to radiator fins... It only looks so. There is a gap of 1/2", this is more than sufficient. My fan is running precisely on needle bearings with almost no play. So no extra safety space needed. Though, the distance is also defined by the fan itself, the length of its thin neck.

[rainer]

Ford placed a spark timing control and a carburetor main jet control at the driver's fingertips. Learn how to use them correctly, and use them, as needed and when needed.

You could have saved the time for writing this, TXGOAT2. Not really helpful.

What this levers and knobs are doing, I know. I asked for the most likely reason for running hot, to do then the right things. -- You see the little difference between "trial and error" and "doing it right"?

[TXGOAT2]

Read your owner's manual regarding use of the engine controls.

[John Codman]

It seems that we are making something fairly simple into a big deal. Start the car, when it reaches something close to normal operating temperature, check the temperature of the coolant in the top tank of the radiator. With the same probe check the temperature of the bottom of the vertical tube closest to the radiator outlet. The temperature should be about 40 Degrees Fahrenheit or around 22 degrees Celsius cooler at the bottom of the radiator then it is at the top. If it's not, you have now found the problem. I realize that a brass radiator will be expensive, but if that's the problem, there is only one way to solve it.

[TXGOAT2]

Does the coolant actually boil? If you measure 200 F at the water outlet, that's not a problem.

[rainer]

Hello, TXGOAT2.

Yesterday I did some final tests. I had the plan to take out the carburetor and look into the bowl (if float is correctly adjusted and/or dirt is inside). Reading the User Manual where you pointed me to, I found a description of engine running hot, carburetor settings, ..., and that the engine is running better and cooler with lean mixture than with rich mixture. So I wanted to do some tests before taking out the carburetor.

Test of gas-flow into carburetor.
With open gas-valves, I opened the drain on carburetor. The continuous flow of gas coming out the engine never can swallow, so the entire gas-flow cannot be clogged somewhere.

Testing the mixture setting.

• First I carefully closed the main-jet and made a marker onto the adjustment knob, then I turned it back to the former position. It was 1 1/2 turns from close.
• I started the engine and let it idle to get warm for 10 minutes. See lever settings in below picture.

  

• Now I wanted to find the lowest lean-setting, so I started to slowly close the main-jet. I expected to find a position where the engine starts to run bumpy within 1/2 ~ 3/4 turn. Surprisingly I was able to turn the needle in 1 1/4 turns until the engine started to idle a very little bit bumpy. After a very little further turn (~5 degrees?) it immediately stalled.
• I opened the main-jet 10 degrees (a very little more than where the engine ran bumpy) and started the engine. It started easily and idled smoothly for many minutes (then I turned it off). It also accelerated fine when opening the throttle.

What I want to ask:
Is this for sure too lean point really so low?
This very long way to there (1 1/4 turns) and then very sudden stall at 1/4 remaining turn of main-jet lets me think about the main-jet. Can it be damaged when the main-jet-needle was too strongly tightened before me, or is this engine indeed running is such wide range of mixture (what I cannot really believe)?

Well, with this extreme lean setting the car will never run well (when driving) at all, that is clear,but it seems I ran it (with needle 1 1/2 turns open) relatively rich. This possibly is the reason for running hot. In cooler autumn weather the radiator was able to get that heat away, but in summer it was/is not. I remember, during my last travel there was always an odor of gas even when driving at 50 km/h (31 mph), and this is an open car.

I will still verify that the float is adjusted correctly (and hereby the gas-level inside the bowl), this cannot be wrong. I want to do this because I read that the level has much effect on richness of mixture between idle and driving. Scott Conger also told me that later carburetors had a bigger float because the tank was in higher position (higher pressure, flow-valve not closing well on bumpy streets), what could cause side slight problems with gas-level in my car (where I have the tank below front seat).

Any suggestions?

[frank_w]

Greetings Rainer,
I'm not sure I understand correctly, but are you saying you suspect the reason for your overheating problem was running too rich (=zu fett, zu viel Benzin)?
If so, the opposite is true: running too lean (=zu mager, zu wenig Benzin) causes overheating.
The way I set the mixture (your mileage may vary):
- close needle valve all the way, then open roughly 1 1/2 to 2 turns.
- start engine and adjust ignition and throttle for a smooth idle
- slowly turn needle counterclockwise (richer mixture) until engine starts to miss
- from that point, slowly turn clockwise (leaner mixture) until you reach a point where the engine starts to speed up.
- turn needle counterclockwise just a little bit so the engine slows down again

The way the engine responds to these adjustments, as in, how many turns you need from too lean to too richt is dependent from a number of things. Among these as you stated, is the condition of the main jet, condition and angle of the needle tip etc.
I don't know what type of carb you're running, but the needle on most of these is easy to check, just undo the clamp nut and screw out the needle, then check needle for straightness, burrs etc.

[Allan]

When I adjust the mixture control needle I do the following. Screw the needle down to make the mixture leaner until it stumbles. Then wind it back out again and note where it seems to run best. Then keep winding it out, getting richer, until it stumbles again.. Now wind it back down again to see where it runs at its best again, and note the position of the needle. Is it in the same position as it was when you were coming back from the lean side?
I usually find some variation between the two positions. I set it at the second position, coming from the rich side, rather than the lean side. Running lean will make the engine run hotter.
This might help.

Allan from down under.

[TXGOAT2]

It sounds like your main jet needle may be damaged, as you suspect. If the needle is damaged, it can make adjustment difficult. Also, most all carburetor adjustment linkages have some slack, or lost motion, and this must be accounted for when making fine adjustments. I would remove, clean, and inspect the carburetor, and replace the main jet needle and seat if they are damaged or worn. Your radiator is probably not in top condition, but minimizing other things that can contribute to overheating may allow you to get by without replacing the radiator. It is normal for a Model T engine to run at 180 to 190 F in warm weather. Anything less than boiling is acceptable. The tendency to boil at higher elevations can be offset by using up to a 50% blend of ethylene glycol ("green") antifreeze. Use a good quality 10W30 motor oil. It will provide much better lubrication, film strength, flow characteristics, and heat resistance than straight mineral oil. It will also prevent carbon and sludge deposits.

[TXGOAT2]

Another thing to check: Be sure the entire exhaust system is free of obstruction, such as dents or insect nests. It is possible for the muffler to become clogged with soot and rust. Any unusual restriction in the exhaust flow will contribute to overheating at higher speeds and loads.

[John Codman]

The engine should run hotter with a lean mixture, not cooler. Are you sure that you are not operating the controls backwards? The fuel/air mixture becomes richer as you open the mixture control (turn counterclockwise).

[rainer]

Hello. I want to thank again for all the ideas and comments. They were a great help in solving progress.

Yesterday I found time to check the carburetor and do a final test drive of 20 kilometers, All the time the motometer normally was below the hole, at longer continuous uphill drive it reached the center of the hole but returned to below very quickly. LOTS better now.

So I want to share that I hopefully solved the temperature issue.

What I did:

• I opened the drain valve of carburetor to see how much gas is continuously flowing out. For sure more that this engine can burn, so the flow is not clogged somewhere.
• I took out the carburetor and partially disassembled it.
• Bowl and all gaskets are in good confition (re-used them therefore)
• No dirt inside the bowl, bowl in almost new condition on inner and outer side.
• Float was and is correctly adjusted. It was parallel to the carburetor when I turned the carb upside down, and it was freely moving, too. Scott told me there should be the smaller float inside, this also is the case.
• I turned out the main-jet needle, It has a sharp tip and no groove(s) on its cone. Only the brass thread is minimally worn where it was moved often for mixture adjustment, but this is so minimal that it does not matter (between almost no and a very little friction. I could tighten the needle-nut a very little more and this solved that.
• The main-jet I did not take out, but I blew compressed air through it to get out dirt (if there is any) Then I visually inspected the center bore. It is round and estimated 1 mm in diameter. So this main-jet was/is also fine.
• I also corrected the throttle lever. It was a bit twisted and bent.

From what I have seen, this carburetor is in almost perfect condition.

Finally I fixed minor problem with throttle-rod at carburetor end. This rod is bent in a 90° angle with inner radius of 2~3mm. So the actuator lever's hole was worn out because the rod always rubbed with its "round edge". I wrapped a bit of iron wire around the rod to keep it 2mm lifted, so the straight part is now inside the lever's hole. LOTS better than before and does not hurt (see picture below).

My "throttle-rod lifter".


As mentioned previously, I also increased the angle of radiator fan blades. Before I could not notice a noteworthy air-flow at center of Cylinder 1, now it is lots more, even on idling engine. Thanks for notifying me! Below you see the new angle, I marked the old angle in this picture, too.

Ventilator Anstellung.png (483.09 KiB) Viewed 1669 times

Green is new angle, red is previous angle.

Conclusion:
The carburetor was fine (now verified by inspection) and was finally re-adjusted. Possible there was an almost invisible amount of dirt somewhere, but I don't think so. The air-flow through radiator (and then around the engine) is much better than before.
This combination most likely solved the temperature problem.



What I still have
is a decent bucking when engine is running above 50% speed (starting at 30~35 km/h kph). Every 2~4 seconds a very short loss of power, but no false ignition. Because of this heavy flywheel I cannot say if this a full power loss or only a minor drop in power. I was told that this is not usual.
Does anybody have an idea on that?

Flow into carb is verified to be more than sufficient. So getting too lean at higher rpm cannot be caused by sinking gas level.
I have no heat-pocket on carb-inlet.


Rainer

[Loftfield]

Model T's are not that complex, helps to stop pretending they are Aston-Martins or the like. Over heating comes from several factors. 1. Spark timing, make sure timing is correct and advanced properly: retarded spark = hotter engine. 2. carburettor: when you get the needle valve adjusted remember to open the needle valve a tiny bit more. Too lean a mixture leads to hotter engine. 3. Radiator: Put a gallon of vinegar into the radiator, the rest water. Leave the vinegar in for a couple weeks, drive with it. Vinegar attacks only corrosion, won't touch clean metal. Drain, and see if it helped. If not, then the trouble may be that the bonding between the radiator tubes and the fins has broken down, a common fault on older radiators as the brass de-zincs, becomes brittle and cracks. I know of no sane repairs for this condition other than a new core or a new radiator, maybe someone else knows how to repair broken bonds between tubes and fins. The above advice presumes you don't have dragging transmission bands or other mechanical difficulties. Since your car does OK at lower ambient temperatures I am opting that your problem lies in the radiator. Maybe you can borrow a radiator from a car that does not have a heating problem just to check.

[TXGOAT2]

A manifold heat device may improve performance if the bucking problem is moisture or frost forming in the intake, which can occur at well above freezing temperatures if ambient humidity is present.
Another possibility is a leak at the manifold or carburetor gasket causing a lean mixture. Timer problems are a common source of rough running at road speeds. Worn or dirty timer parts, lack of lubrication, or too much lubrication can cause rough running. The original type timers require frequent oiling with a light oil. The wires connecting the timer to the coils can often get chaffed and short to one another or to ground. This often occurs around the timer and fan belt or where the wires pass through a clamp.
High tension spark plug wires can leak current or cause inductive misfiring if they are too close to one another or if the insulation is aged or worn.
Good coil adjustment is critical to good engine performance, and external coil contacts with the internal coil box contacts must be secure. I had problems develop with my car bucking and cutting out on the road, and the cause was poor contact between the coils and the coil box. A couple of cardboard shims eliminated the problem.
Loose debris in the gas tank or gas filter may become agitated when the car is on the road and cause fuel delivery issues when driving at road speeds, then settle out when the car is parked, allowing good fuel flow until the car is taken on the road again. I'd check the fuel tank, fuel line, and filter for any indication of foreign matter. The fuel tank cap vent must be clear of any obstruction, and the fuel line must be kept clear of exhaust pipe heat.

[rainer]

A manifold heat device may improve performance if the bucking problem is moisture or frost forming in the intake, which can occur at well above freezing temperatures if ambient humidity is present.

But this also happens on my T when the engine is not warmed up. I start it, let it idle 1~2 minutes, then I start driving. I give it this 1~2 minutes to get some oil to the first bearing over internal and external oil tube.

I actually see not much difference between driving at road speed or speeding up the engine on parked car and/or cold or warm engine. Appears to depend on "rpm" only.

I will have a look into the timer, wipe it clean using an oily cloth, and lubricate again with a bit with sewing machine oil (should be thin enough for 800~900 rpm the timer does at most?). I have a roller timer (original style), with spring-loaded arm and a roller on tip. The spring I remember well, it broke some years ago on the road. What a mess, everything hot, ... This ended the drive that time, I replaced the spring later in my garage, on cold engine, by a new one from DIY market in similar size and strength. Since then I had the timer never open, so it sounds reasonable to clean it again.

How often should the timer be cleaned and re-lubricated as rule of thumb ? I haven't done it for 2 years now, but I drove not so much since then, perhaps 800km ?

I also think about testing my coils when I have a chance to do so. I read about 1.5 A almost everywhere, but I nowhere can find a voltage in all descriptions. Does voltage have no influence on coil current? Only wondering, because it is a huge difference between 6V Battery and 28V on a magneto. Btw., I do not plan to buy a tester for hundreds of dollars, my plan is to buy a mechanical Ammeter for AC/DC (costs a few dollars in China) and build a tester by myself from plywood. A little box with a built-in battery, Ammeter, switch, a used old spark-plug, and a chamber with contact springs where I slide in the coilbox.
It would help me a lot to know a useful voltage for adjustment. 6V or 12V, or more ? My initial thought is 12V, this is wight between old time battery voltage and magneto and can easily come from three 18650 LiPo cells in series. They are small, cheap, and give high current, so they do not falsify the measurement.

[TXGOAT2]

Ford recommended lubricating the timer every 200 miles with a light oil.

[TXGOAT2]

I think the Ford repair manual gives some direction on coil adjustment. It can be difficult to adjust coils without the right equipment. A coil with a bad capacitor or points in bad condition can't be adjusted correctly. I would clean, inspect, and lubricate the timer first. If you can locate someone with an HCCT or an ECCT, the coils can be tested and adjusted to give good performance and smooth running. In my experience, a car with one or more coils out of adjustment will run very poorly, even if the coil gives a good spark and everything else is in good order.

[rainer]

I think the Ford repair manual gives some direction on coil adjustment. It can be difficult to adjust coils without the right equipment. A coil with a bad capacitor or points in bad condition can't be adjusted correctly. I would clean, inspect, and lubricate the timer first. If you can locate someone with an HCCT or an ECCT, the coils can be tested and adjusted to give good performance and smooth running. In my experience, a car with one or more coils out of adjustment will run very poorly, even if the coils gives a good spark and everything else is in good order.

TXGOAT2,
this is exactly what I plan. Start with timer.
When I have luck and one of our members in out Model T Club has a coil tester, I will test my coils when I meet him.

[TXGOAT2]

The Ford service manual provides a procedure and specifications for adjusting coils when using a Ford HCCT, or hand-cranked coil tester, which is basically a Ford magneto fitted with a hand crank and a voltmeter and an ammeter. When using this method, each coil is adjusted to draw an indicated 1.3 amps when the HCCT is revolved at a speed that provides an indicated 6 volts. This is for the later type KW coils with a cushion spring. It would be difficult to do this using the magneto in the car, since the idle speed would probably not be steady enough to obtain meaningful readings even if the proper type of volt and ammeter was available. Making any actual adjustments with the coil in a running car would be difficult, too.