overheating

[Acadia_john]

My 1926 car has been running well with the Motometre showing the red just below the little window. All of a sudden a few days ago it started pushing the Motometre thermomoter to the very top. I changed a questionable plug and a week buzz coil and readjusted the commutator. Still goes to the top ( 225 degrees F ) after only 8 miles. What can I do next that may help it run cooler?

[Steve Jelf]

Is the car really running hot, or is the motometer just saying that? 225º is well above the boiling point. Do you hear actual boiling, with steam shooting out of the overflow? If it really is running hot, something here may help: http://dauntlessgeezer.com/DG96.html

[Mark Gregush]

Besides what is talked about in Jeff's link, you could be running too lean or rich or not adjusting the spark properly. If it has a water pump, make sure the shaft is turning.
Sorry about opening the water pump can-of-worms, because you will now get a hundred post about how the Model T does not need a water pump even thought you do not say it has one, yet. It just twists some people undershorts in a knot! LOL

[TWrenn]

Other questions we don't know the answer to are 1. Round tube radiator or flat? We all know round tubes run warmer.

2. What has the ambient temp been? Near 90 like around here? It makes a big difference.

3. Age of radiator? It MAY just be time for a good cleaning...even to the point of taking it into a radiator shop and have them boil it out. Made a HUGE difference in my original round tube radiator in my 25 Fordor.

[Jonah D'Avella]

I have a 26 touring as well with the same problem let me know if you figure out the problem.

[TXGOAT2]

Most cases of overheating and boilover are related to a dirty cooling system. The remedy is to clean out the entire system, including the block, head, radiator core, and air passages through the radiator core. Other possible causes include a leaking head gasket, cracked block, very late timing, and dragging brakes or transmission bands. A cracked block or leaking head gasket may not show any external leakage. A lack of any evident external leaks does not rule out a bad head gasket or cracked block. However, most overheating problems are directly related to rust and other debris in the cooling system, and cleaning the system will usually reduce or eliminate overheating problems.

[paddy1998]

The question here is what caused the sudden change, not what generally causes overheating.

What's changed from before?

Also, before making adjustments and changing out parts I'd confirm that the motometer is not the problem. Get yourself a laser thermometer (which is also handy for grilling and smoking) and check to be sure the meter isn't lying to you. Aim it at the outlet on the head.

[speedytinc]

The question here is what caused the sudden change, not what generally causes overheating.

What's changed from before?

Also, before making adjustments and changing out parts I'd confirm that the motometer is not the problem. Get yourself a laser thermometer (which is also handy for grilling and smoking) and check to be sure the meter isn't lying to you. Aim it at the outlet on the head.

FWIW I had recent sudden overheating issues on 63 ford. Chunks/flakes of rust worked their way into the tube openings slowing down water flow. I have had to remove the radiator several times & back flush. Runs cool until tubes refill with flakes.

[Scott_Conger]

An absolutely sudden change toward overheating, with NO prior changes, right?

If the car sat for 7 or more days since running properly and now is suddenly running hot, I would suspect a rodent nest or otherwise partial blockage in the muffler causing back pressure. It is simple enough to rule out.

[speedytinc]

An absolutely sudden change toward overheating, with NO prior changes, right?

If the car sat for 7 or more days since running properly and now is suddenly running hot, I would suspect a rodent nest or otherwise partial blockage in the muffler causing back pressure. It is simple enough to rule out.

There was a prior change. This was a "new" 40 year old rebuilt motor. Ran cool for a week, then temps started rising as the hidden rust worked its way into the radiator.

[Scott_Conger]

So there was a minor addition recently...like another engine??

So much for offering advice on what is purely a guessing game designed to keep people occupied. Off to more productive things...

[Luke]

So there was a minor addition recently...like another engine??

So much for offering advice on what is purely a guessing game designed to keep people occupied. Off to more productive things...

Scott,

Love the response .

However I suspect that in this case John was talking about his '63 and was explaining how he thought his rust issue came about in the hope it might help others with their T's?

Luke.

[Poppie]

Well said Luke,
Its a shame people don't think before they chuck a mental ..n

[Acadia_john]

Thanks all for the helpful comments. The digital thermometer says 224 degrees. It was a quick change from normal. This heating problem started after some timing issues( including backfires) which I believe I have corrected. After looking at all of the comments it seems as if there might be a bad head gasket. I don't even want to think about a cracked block. It was a complete rebuild including new babbit and it has been working great. It was a new style head gasket which I hope will be the culprit. Any further comments or ideas will be appreciated.

[Luke]

John,

A simple and effective test for head gasket (or the other thing you don't want to know about) is to pressurise each cylinder in turn and look for bubbles at the radiator.

To do this you need to make a simple air tool that screws into the spark plug receptacle in the head, and to which you can connect your air compressor. I've done this in the past with two or three common brass fittings - it'll be easy with the T.

Screw the new tool into (say) #1, put the car in high and turn the motor over until the valves are closed for that cylinder, set the handbrake on. Apply air and look for bubbles. Do the same for each cylinder.

Typically the air will want to turn the motor (which is why you need to leave it in gear with the brake on) so just ensure you're initially clear of anything that might hurt if it moved a little.

A good gasket/block will not allow air to escape from the cylinder into the water system. Conversely a faulty gasket, or the other thing, will most likely allow air through to the water system, which will then head off to the highest point at the radiator header tank...

This may save disturbing a possibly good gasket, and is a useful diagnostic tool for the future as well.

I suggest trying this out first, and report back the results?

[TXGOAT2]

If a rebuilt engine was installed and run for the first time, was the head retorqued?

[speedytinc]

So there was a minor addition recently...like another engine??

So much for offering advice on what is purely a guessing game designed to keep people occupied. Off to more productive things...

Scott,

Love the response .

However I suspect that in this case John was talking about his '63 and was explaining how he thought his rust issue came about in the hope it might help others with their T's?

Luke.

My apologies to all of you for creating some confusion here. I mixed up this post with the other overheating post.
The other post was for a first time T owner.
My example for him is not pertinent & not intended for this situation of a known running T with a sudden overheating issue.

[TXGOAT2]

If the car suddenly begins to run hotter, check to be sure the spark control linkage is still working. Once in a while, the lining in a radiator hose can become detached and cause obstruction to coolant flow.

[Quickm007]

You may look your timing... it is often the responsable for overheating. Also be sure the fan properly work without sliding belt... Also be sure the fan blade are correctly oriented. Other point, flush your radiator as Jeff said. Last point to validate, you may have leaking intake cause overheating either. I'm saying all these elements because I personnaly experienced all these issues as well

Good luck.