Overheating problem

[Daba]

I recently picked up a 1930 tutor and at idle it’s fine I can drive about a mile and a half and it starts to overheat if I pull over and stop it goes away as soon as I get up to speed it overheats I checked and rechecked the timing many times. I don’t believe it’s timing. I have flush the radiator a couple times and checked for a thermostat which there is none. The car runs awesome by far the fastest Model A I’ve ever owned out of the four other ones I have. Any suggestions would be great thank you in advance Daba.

[Gene F]

Are there bubbles visible in the radiator when the engine is running? Perhaps when an assistant steps on the throttle?

[jack backer]

Chemical at home radiator flush doesn’t work well with a model a radiator plugged with a combination of water pump grease and rust.. along with dirt. Removing the radiator and flushing them back and forth with an industrial (truck or equipment shops have them) hot water pressure washer with degreaser chemical heats the radiator, expanding the tubes allowing the degreaser to work..saved a few thrown away radiators that way.

[Marshall V. Daut]

A common mistake among newbie Model A owners is to fill the radiator up to the filler neck. What happens when the level is this high is the water heats up, expands and forces its way out through the overflow tube and from beneath the radiator cap, or through it if it's a two-piece cap such as a Flying Quail. Bubbling hot water exiting the radiator makes the owner think the engine is overheating. If the engine is not slowed down or stopped, this bubbling action is self-sustaining and will eventually deplete the coolant supply to the point that the engine actually does overheat due to loss of coolant.
Are you sure the engine is actually overheating or does the previous description cover what is happening? Of course, it's possible that the radiator is clogged or tubes have been pinched off in an effort to stop a past leak. The engine block water passageways could also be corroded and restricted by years of rust and scale, akin to varicose veins and arteries in humans. But for a newbie, the usual cause for this "overheating" condition is counter-intuitive = too MUCH coolant in the system. Most Model A radiators no longer have the baffle in the upper tank that is supposed to stop this bubbling action from occurring. If this baffle is missing in your upper tank, you will be able to peer down inside the radiator and see when the water level just covers the top of the radiator core. This where you should stop filling the radiator. Enough space is left for the heated water to expand without bubbling out. If, however, a baffle is in place, you won't be able to see down into the upper tank to where the water is above the core. In such a case, fill the radiator until it almost reaches the filler neck. Open the petcock on the return pipe beneath the generator and allow the water to run out of the petcock for about 10 seconds. Then close the petcock. That will put the remaining water in the radiator just above the core where you want it.
Before panicking and replacing the radiator, try adjusting the coolant level as described. Do this with the engine and water cool. If that doesn't stop the bubbling action, THEN it's time to consider the radiator itself, which may need to be rodded or even replaced in extreme cases of functional deterioration.
Marshall

[1crosscut]

Stick a dial meat probe type thermometer directly into the coolant and measure the temperature. This way you/we will know for sure if it is actually overheating or if it is something else.

[eagle]

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Put a gasket under the radiator cap so it doesn't leak. Make sure you are running the advance properly. Advance until it just starts to ping when pulling hard, then back off a click or two. Make sure you re-torque the head periodically. As has been said previously only add enough coolant to cover the core. If it still overheats or spews coolant then you probably need a new radiator. You can try having it rodded or boiled. DON'T just live with it. An engine that is truly overheating is short-lived. A new engine is expensive! I know someone who insisted that it was "normal for a model A to overheat" he ended up having to have his engine rebuilt...and a new radiator.

[Daba]

Classic rookie mistake I should know better being as this is my seventh Model A, I overfilled the radiator. Took the advice made sure it was below the upper plate and Wala no more problems. Thanks for all of your input really appreciate it. Hopefully someday I can chime in with some advice but not today.

[Marshall V. Daut]

Hurray! Problem solved by communal input and it didn't cost you a cent! You just saved an $800 radiator replacement and a ton of grief. Thanks for getting back to us with your solution. Your follow-up posting may help others here with their own "overheating" problem. Much as we all love our Model A's, there are certain "traps" built into its design that can easily lead beginners astray (or those who have forgotten essentials of Model A quirks). You found one of them.
Marshall

[mavche]

I have a similar problem with my '31 A, but my car has a new radiator installed. I shall follow the previous advice plus any more that is offered.

[Charlie Stephens]

Is the fan on backwards? Don't laugh with some of the reproduction aftermarket fans that have blades that bolt on you could actually have that problem.

Charlie Stephens