Our club has been working on an overheating 1920 Model T Firetruck for the local fire department. The problem is that the truck is used mostly for parades, idling along at a very slow speed. Depending on what the outside air temperature is, it will boil in 10 to 15 minutes. Here are all the things we have tried so far: 1)pressurized the cylinders individually with shop air to see if there were any leaks into the water jacket (none); 2) tried three different water pumps, the pump with the most flow actually made the problem worse, so we tried no water pump, still the same; 3) temporarily attached a 12volt radiator fan on the front, very little difference; 4) borrowed a new Brassworks radiator to try, it was better but still showing over 200 degrees on a cold (60F) day which just is not going to make it on the 4th of July; 5) Pulled the head, filled the block with phosphoric acid for one week, flushed, ran a rotorooter type of flex cable in and around through all the passages and repeated the phosphoric acid for another week, flushed and rotorooted again. Installed a different head that had been hot-tanked (whistle-clean) and faced. No change, boiled after 15 minutes on a 75F day. Timing is correct, it is not retarded. The data point for comparison is my runabout which will idle retarded indefinitely and never get above 165F. We are at our wits end and wonder if anyone else has faced a problem like this and solved it?
I'd check the carb setting next. You've eliminated most of the suspects and running lean would be my next thing to fix or eliminate.
Check the steam holes in the block and head. When they get scaled up, they restrict the flow of water in the hottest area of the block and can cause a significant rise in temp. They should be 1/4". You should also check that the transmission bands are on the loose side. Any dragging will cause heat.
One idea for you. Are you sure the exhaust is not restricted? That will cause overheating. A rat's nest or insect nest will clog it up. Try running it with the exhaust opened up.
I will heat real bad if you are running it with the timing retarded. If your sure that your not getting compression in water system, Get a new radiator.
Things that would cause the engine to run hot may be:
Running the mixture too lean or maybe a partial blockage of the main jet.
Running with timing retarded.
Water level below the top of the radiator core.
Blockage of water flow.
Working the engine hard and low speed, in other words lugging the engine.
Restriction in the exhaust system.
Lack of air flow through the radiator.
Old radiator and poor heat transfer from the core tubes to the fins.
Too much friction in the engine. Maybe tight bearings or pistons/rings.
Running a 50/50 mix of antifreeze will make an engine run hotter and more likely to overheat then running less antifreeze.
Air temperature very hot, like 120°F+.
Sounds like a lot has already been done. If you are using and/or tried a new round tube radiator, you may try a flat tube radiator. A flat tube radiator is about twice as efficient as a round tube.
Has any work been done to the engine recently, rebuild? Bored out? Does the engine make any power or is tired and worn out?
Is the headgasket on right?
Check to make sure the intake manifold is not sucking air, you may have to have the manifold resurfaced. If the engine block has been bored out a large amount and the water jacket has had a lot of metal removed because of heavy rust, you may not be getting enough heat transfer. To fix this the block may have to be sleeved.
Another suggestion you can try, is to replace the head with an aluminum one. I used a popular aluminum high compression head, which did drop the temperature quite a bit. But the quality of this particular head has dropped way off, as I even had to have the head surfaced before I could use it, among other things. I just bought a Prus head for the 24 I am doing, the quality on this head is excellent.
Might sound silly, is there oil in the engine to the correct level?
PUT ON A WATERPUMP
Bob, one question on boiling? Yrs ago I had a
1922 (boiling) all over the hood and windshield,
now thats boiling. At present my 23 will hit
200 degrees but stays there or maybe will shoot
to 210 but doesn't throw up on the hottest days
and I am bored to .060 so there is still meat for
transfer. Hope you felt the radiator cool on
bottom hot on top if not and the whole radiator
is red hot somebody in there is still plugged up.
just thinkin out loud
Well. It is a "fire" truck. =) LOL
Bob - how big/heavy is the fire truck? You're basically making the cooling job as difficult as possible when you take a really heavy vehicle and want run it in a parade.
Are there engine splash pans in place? If so, remove them, that will help with air flow.
Check oil level
Make sure head gasket is installed correctly. You can get it backwards and have the small port from the gasket covering the large hole in the engine. The rear port is the larger of the two.
A flat tube radiator is a MUST. I'd also check that you have enough angle on your fan blades. Since this vehicle is specifically meant to run in parades you might consider getting a fan shroud from The Brassworks. That will make a big difference.
Err on the side of running the car rich. If you turn the knob in until rough and then out until rough, go in just enough to get smooth, rather than finding the middle between the two spots.
If none of that works then it sounds like you'll just have to get rid of the truck. I'll be happy to help you with that. LOL!
I would bet you had the problem fixed when you tried the new radiator. Put it back on, and run the heck out of it. 200 degrees in the top tank is correct operating temperature.
"it was better but still showing over 200 degrees".
Lots of detail but you fail to say where you are measuring the temperature and how.
Also how do you know you have an overheating problem? Is water coming out of the overflow tube? If it's coming out from under the radiator cap, do you have a gasket installed where the cap meets the flange in the neck?
How are you setting the timing? Are you using that gauge with a hole in it or are you using some other method. I agree that you might have had it fixed or mostly fixed when you tried the new radiator and if that new radiator was NOT a flat tube type then order a new flat tube radiator and you will be OK once you get the timing dead accurate and the mixture running rich. Do you have a moto-meter temperature gauge on the top of the radiator? Gurgling is not unusual from a radiator and is not "boiling". By far the most often cause of overheating is trying to use an original T era radiator. They hold water just fine but have long ago lost their ability to act as a heat exchanging device because the tubes do not make good contact with the fins and hence there is no heat transfer. This cannot be repaired as a practical matter by any means other than putting on a new radiator. Water pumps never help overheating Model T in my opinion.
How does it run at normal cruising speeds? Could it be you are filling the rad to the very top instead of just well above the core and the level is self correcting (spitting up) and you are mistaking it for overheating? It's easy to think full is better. This is what happened to me in my first parade in winter no less. Since then, I've never had a problem even in summer parades and with a tired old rad. Perhaps the fire department ordered the truck this way to reduce response times. Just kidding. Try everything here, I'm sure you will solve it.
You've cleaned it, tried a new rad, had an electric fan on it, pulled, cleaned then replaced the head, timing's OK plus a few other items I would have tried too. I'm thinking you've got a block crack somewhere that's bleeding into the cooling system. There's nothing else left to try. Only opens when hot.
Another .02 I think the engine pans should stay on and if they are not present they should be! The engine pans help air come through the radiator instead of around it.A fan shroud is good but Henry tried that in 1917 and only 1917 so what brand fan belt,Is it tight and with a shroud how will you adjust it? I could never run pumpless until i switched to a Anderson Timer.I stay cool now with my ?? 50+ year old round tube rad and removing the small tin shield at tho bottem of the wood dash really helps!! When the floor mat starts to rise i'm going too fast!! Bud in Wheeler,Mi.
Kenneth if you're doing regular driving, then the fan shroud restricts airflow too much. Since they are mainly just doing parades, the fan shroud will help the fan perform better.
Not that it matters but did the fire dept get it this way or did it develop afterwards? This might eliminate something that was done wrong. Like an improperly installed head gasket. You did say it's a club working on it so I'm assuming several sets of eyes would have spotted that. After re-reading your initial post and reviewing all you've done I'm standing by block damage.
Silly question, What weight oil are you using? I had some straight 50W that I thought would be good in the hot Florida Sunshine.... Boy was that a mistake ! of course I was a newbie at the time.
Seth,After breaking my first crankshaft i have not tried to hit 52 mph again so what is normal? I fail to see how a fan shroud could restrict air flow as they make the fan suck the air through the radiator?? My only problem is the fan shroud was only used in 1917 so tell us why?? I do 2 parades a year,one is about a mile at walking speed and the other is the Gaslight Parade at the OCF for at least 2 hours! Bud in Wheeler,Mi.
Bob it sounds like you have been very systematic in your analysis. The only things left to completely eliminate a cooling system problem are: 1. Check the steam holes, if you haven't already done that. 2. Revisit the head gasket orientation, it's easy to flip them end for end, misaligning the steam holes, as I'm sure you know. 3. Pressurize each cylinder when hot at BDC to check for air bubbles in the radiator, which you may have done.
Having done these things, then the problem is likely external to the cooling system which would point to timing, fuel mixture or engine drag. If it is a freshly rebuilt engine it may just need to be broken in some more, but It sounds like you have covered all other bases.
I'm only suggesting the fan shroud for the specific purpose of keeping the fire truck cool during the parade. I'd say driving like normal for a T is anything from moving to about 45 or so, unless it's a speedster and meant to go faster.
In the parade case the vehicle will mostly be idling or barely above an idle. More importantly, the vehicle will mostly be stopped or moving at walking speed: ie not getting much air through the radiator. With a shroud you get better airflow through the radiator because the fan is able to more actively pull air in. Virtually any speed above walking is going to produce more airflow (and thus cooling) than the fan can provide. That's why plenty of folks don't even run fans at all.
Conversely, if you drive at even 10 mph, you are moving more air across the radiator than the fan/shroud would be able to when sitting still and idling. However, once you get past 10 mph (the specific threshold may be higher or lower, I don't know) the incoming air through the radiator has to get through the shroud opening and fan and is essentially being bottle-necked. So as an exaggerated example at 35 mph you're actually losing the cooling effectiveness of your radiator because not as much air can pass through the radiator, it's blocked by the shroud and fan.
Another good example is how modern electric fans on radiators only run when necessary. If the car is moving at 55 mph the fan motor shuts off and just lets the fan spin in the wind so that it reduces air resistance as much as possible.
If you decide to fabricate a fan shroud, ideally the fan blades should fit halfway into the fan shroud opening. Also, seal around the shroud so that the fan pulls all the air through the radiator instead of through a bunch of gaps around the shroud.
Is it really overheating or is the T just doing what it does?
If I put too much water in the radiator of my T it pushes water out of the over flow and radiator cap. (I don't have a gasket on the cap.) My T likes about an inch of water over the radiator core.
If I'm doing a parade and the Moto Meter gets to the top I have my passenger spray the radiator with mist of water from a plastic water bottle.
I'm with Ed. My money is on the radiator. 200*F is not abnormal. If you cannot touch the lower water pipe without burning yourself, the radiator is not cooling like it should. Even if it is 200*F going into the top, it should be cool enough coming out the bottom that you can hold your hand on the water pipe for at least a few seconds, if not indefinitely.
How much paint is on the radiator? Too much paint on the fins will prevent heat from transferring from the fins to the air.
The valve heads should be setting on top of the block, if they are ground down in to far, the motor will run hotter, and to the point of running to hot.
Especially, the exhaust valves.
The engine just can't breathe.
I have only run a few times in a parade, but one thing I figured out soon was to leave the hand Brahe at mid point so it is in neutral with no peddles depressed, increase the throttle to a moderate engine speed, and use the low peddle as necessary to move ahead. This has allowed me to do parades without overheating in my smaller radiator end 15 touring.
I think Jim Thode was onto it. I think the crank and rods maybe too tight.
Timing gear out a notch or 2?
Stay away from slow parades or go last in line or first would be better. That stop and go business of a parade will make Model A's boil over also.
If a new radiator made things better, then you know that at minimum, you need a new radiator. Anything else you try will be meaningless while still using a bad radiator.
This does not address the specific overheating problem, but because the "T" fire engine is used mostly for parades, a Ruxtell rear end is a huge improvement for many reasons, including the fact that with low pedal engaged, the engine (and fan) can run at considerably faster idle which will help a lot.
I've read this whole thread and unless I missed it, I wonder if this "T" fire engine really has an overheating problem, or, if it is not fully understood that a Model "T" thermo syphon system only works properly when the coolent is very, very close to boiling temperature. Many people don't understand that with the engine at normal operating temperature (at or near boiling) it is normal for the coolent in the radiator to rumble and gurgle when the engine is shut off. Also, as several have pointed out, if someone insists on filling the radiator too full every time they think the engine has overheated, it will always purge itself of the excess expanded coolent the next time the engine is started and run up to full operating temperature. Someone did ask if coolent was only coming out of the overflow pipe when hot, or if the radiator was actually boiling over,......???
To Bob Meneely:
Bob I had typed a short note to you guys about the Fire TRuck and my modem froze.
Here is a short story about a guy here in town(Redding, Ca). He has a Toyota P.U. and it was needing a major engine redo. Well the guys asked my moral support. I told them what I would do and most of it they did. So when the job was done the engine was running it started to over heat instantly. They checked water level the thermostat and everything possible. They were at thier wits end. They asked anybody that had anything to do with Toyota and no body could come up with an answer, till some one said is it possible that the head gasket could have been put on wrong-end for end, well of course the answer hell no you think were that dumb. Well the guys who did the job went to the parts store and checked to see if that was possible and sure as heck it is possible. So they with tail between legs went home and pulled both heads off and found one(not sure which) was swapped end for end they changed the gaskets and it is running like a scalded cat. No problems since.
So this is something to consider. JMHO and story of a local happening.
This may not be the case butttttttttttt it is worth checking.
There is a product called Blue Ice that the V8
members told me about,that you add to the water and it helps out very well, there are several other products today that work just as good and do not cost as much. It increases the surface tension what ever that is. The one I use is green
in color. You can get them from your local parts
store. Also go to Harbor Freight and get a IR
temp. gun. It will tell you where the hot spots are on your engine and any where else. No guessing
Dave Wells & Fred Dimock - In re-reading this whole thread, I guess you guys did say pretty much the same thing I said, but in fewer and more well-chosen words,.....sorry,......harold
No problem Harold. It serves as reinforcement for what we said. While I'm here, I might as well do likewise. I have to agree with earlier postings that it would be worthwhile getting a new flat tube radiator. Then it might be easier to solve the other small problem, whatever it is.
If you are just getting involved taking care of this truck, you might check the oil. It used to be when I was a kid, the older the car the thicker oil you used. Now that I'm older, my old car gets 10W30. The guys before you may have been of my generation.---Len
I had the same problem in 70's when having a 55 T-Bird motor rebuilt. Overheating was caused by a defective head gasket that was not punched properly. I suggest taking a new head gasket and matching it with the old one and looking at the block to match the passage ways. Plus, check the valve timing too.
Lots of good advice above......
Sure would like to read Bob Meneely's description of "boiling".
That question was more or less asked awhile back, but I do not see the answer.
Different people have different meanings of some words...a famous (infamous) politician differed from the norm in a three lettered word definition.
Bob, if you read this, could you please describe what you mean by boiling?
Bob, I hope that you realize that - at this point - you owe it to the many people contributing to (and even more following) this thread to let us know the outcome....
Yeah Bob! Now it's Tuesday. We need a report! =)
There is an in-depth article on solving heating problems before replacing your radiator. It was in the July-August 2013 issue of the Vintage Ford.
The nearby Rockport Fire Department's 1913 Chemical Truck was overheating badly, and someone had even mounted a modern radiator cooling fan onto the inside surface of the radiator.
It also had a water pump, of course, and that was the first thing I removed. I found it packed with rust and crud where it mounted to the block. No coolant could possibly get past it.
It also had a distributor, the second thing I removed.
When it left my shop it ran cool with a new radiator (the old one was good but the fan installation had ruined the appearance), a standard belt driven fan, NO water pump and an Anderson timer and rebuilt coils.
Working great and the guys have a great time with it in parades.
I call it UN-accessorizing a Model T.
Throw those water pumps away, get a flat tube rad.
You sound like me, Frank.
Right on Frank.
Could it be a mouse nest in the muffler?? Bob asks a question and is never heard from again? Bud in Wheeler,Mi.
Answers to questions:
Head gasket is on correctly.
Radiator warm to touch on top fins, cooler on bottom fins, but doesn’t burn your hand, indicating that heat flow to the fins might not be all that great. Forgot to mention, radiator was in shop so tubes are open.
We measure the temperature with a handheld pyrometer at each cylinder and in and out of the radiator. The exterior of the head actually shows over 220 degrees.
We know it boils, because it will shoot a geyser after 10 to 15 minutes.
Engine is definitely not tight, turns over easily with crank.
We have tried a different carburetor.
At this point, definitely need to check for plugged exhaust, hadn’t thought of that one.
All else being equal, a new radiator (flat tube) and a fan shroud are probably the best possible solution.
We only get together and work on it once a week, so the final results will be posted sometime in the future. Thanks for all the great advice and ideas.
The geyser symptom is one from the water pump. Water pumps were used in the day to circulate water during winter driving to help keep the alcohol and water mix working to stop freezing, (there was no Prestone in T days )
A negative of the water pump is it blocks the full flow of super heated water that rises from the block with the thermo-syphon system. The elevated temp water almost hits 200 or so, then pushes rapidly in a big blast up the outlet tube to the upper tank, where it collects and pours down the tubes of the radiator and gets cooled in the process.
The lower pipe will then be filled with cooled water, which is pulled back into the block, by the thermo-syphon action.
Any thing that harms the large flow into the upper tank, or the pull from the lower pipe will just handicap nature's pure system that Ford selected. Remove that water pump.
And make sure there is a metal pipe for the lower return, and not a long rubber hose, as that hose can collapse and block flow during the 'pull'.
Caution on using a 'shroud' on the interior face of the radiator, that will just block air flow, as way tried back in 1917 as a Ford failed idea.
Here is dash mount gage with sensor on the upper outlet, at normal running, temp stays at 180. At hot running, higher speed or hill climbing the temp goes to 200, but after resuming typical motor speed, the temp will drop rapidly, less than a minute, back to 180, as the thermo-syphon system does its duty.
Causes of overheating are motor conditions, generating too much heat. Timing, lean fuel mixture, low oil, fan slipping, etc. Or cooling system, low water, clogged radiator, hoses or block passages.
Bob, some of the fellows may be on to something about the restricted exhaust, gland rings can come loose and turn sideways and cause a problem. KGB
When the water pump was installed, chances are there was a thermostat installed in the upper outlet, where it bolts to the head.
I'd make sure it is out, and the outlet is open and clean. And remove the pump!
I've also seen radiator hoses that collapsed on the inside, restricting flow.
All things considered, though, a restricted exhaust sounds like a good bet.
Does this fire truck have a fire pump mounted on the front of the engine as many fire trucks do, this could restrict air flow through the rad at low speeds. I experienced a severe over heating problem with a modern engine and the final outcome was the radiator. I replaced the radiator twice with two new after market radiators and the problem continued, heads were removed and resurfaced, water pump, clutch fan, thermostat removed and in place and the problem still continued. Eventually I replaced the radiator with a factory unit and the problem was corrected. The after market radiators were faulty. The supplier admitted they were faulty after some discussion and replaced the last radiator I had purchased to this day it is still in the original box in storage where it will stay. Run a substantial flow test through the radiator it should handle a full open garden hose.