'31 A Suddenly Started "Overheating" - List of likely supects?

[irex511]

Hey Folks,

I've searched around a bit, but have some specific that may make this situation different, so wanted to reach out to my expert friends to see if you all have any ideas. As some of you already know, my grandfather passed his '31 A down to me last year and I have been very slowly learning the ins and outs of the car while thoroughly enjoying my ownership.

So, here's the deal. I've had the car for a year and it's been running and driving flawlessly. ~1 month ago, I replaced the temperature gauge on the radiator cap as the glass was cracked (not sure if this is relevant). The radiator has always overflowed a bit (pretty sure it had previously been overfilled, but today, I started the car up, idled it in the garage a bit, and within 20 seconds of driving the temp gauge shot to the top and coolant spritzed out of the radiator cap. I let the car cool, checked that the gauge seemed tight and it had coolant and tried again with similar results.

I know this can sometimes be evidence of a cylinder head gasket blowout, and this was replaced by my grandfather just before he gave me the car (if that's relevant).

So, if it were your car, what would be your list of things to check (and any advice on how to check them would be massively appreciated). Thanks so much for the help!

Cheers,

Mike

[wmws]

Sounds like it could be a head gasket. Did anyone re torque the head several times? When you run it at a fast idle do you see a lot of bubbles in the radiator?

[irex511]

Doubt the head was retorqued. I was there when we did it and just went around the designated pattern with a torque wrench one time.

I'll check the radiator when it cools down...what would that tell me?

Thanks for the help! I really appreciate it!

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[wmws]

The head should be re torqued several times until the nuts don't move any more. If you have bubbles in the radiator it shows compression pressure is escaping into the water jacket.

[irex511]

Worth retorquing it now, or will I likely need a new gasket if it's leaking at this point?

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[1955cj5]

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Originally Posted by irex511

Worth retorquing it now, or will I likely need a new gasket if it's leaking at this point?

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I'd say it's worth a try...

The instructions that came with my head gasket said to torque after the fist run, once stone cold, and again after 500 miles...also when cold.

[irex511]

Great! Will let it cool off and try this and report back. Really appreciate the help!

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[Big hammer]

When the gasket was replaced was the head and block checked for being flat? I have about 750 mi on new head and gasket, countless times of torquing and after winters sleep I found several nuts moved alot. The water outlet nuts about 1/4 turn before tight!

[BILL WILLIAMSON]

Running a thermostat???
Bill W.

[irex511]

Well, I know he had the head tested and planed...not so sure about the block. You're giving me more hope this may be an easy fix...

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[1955cj5]

X 2 on the thermostat....I might take it out until you find the problem...

Where is your temp gauge sensor, or is it a motometer?

[wmws]

Like 1955cj5 said it is worth a try but you probably going to need a new gasket. I would re torque it at least 3 times in the first 100 miles and then maybe again after 500. I do mine once a year just to be sure. 55 ft lbs. If you have to head off again make sure the head and block are flat.

[1955cj5]

Also check the oil and make sure it isn't turning a milky white color....that would indicate that water/coolant is getting mixed into the oil....

Does the exhaust look normal? White smoke means there is water getting into the cylinders...

If you are lucky your leak only happens under pressure/compression......

[irex511]

Exhaust does look normal. Im due an oil change so will check that here soon.

I don't think I'm running a thermostat but will have to check.

As for checking the block, what's the best way to do that? I've always taken heads to a machine shop. Is there a diy trick that I've missed?

You guys are awesome help as always! Without you all I wouldn't even know where to start!



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[wmws]

You will need a machinist rule and a feeler gauge. You could get the machine shop to check your head. If it is good the block probably is also. I think the spec is about .002-.003.

[H. L. Chauvin]

Mike,

1. Every time an 86 year old block with an 86 year old radiator overheats, the most likable cause is usually what nobody likes to even whisper in the dark, at midnight, in the middle of a dense jungle; i.e., the "R" word.

2. You said it ran flawlessly; however, your one (1) hint mentioned is leaning towards a distinct cause of overheating and appears to be possibly getting close to whispering the "R" word: "The radiator has .......... "always" ........... overflowed a bit."

3. If not a malfunctioning thermostat as mentioned above, rather than take off to Mars with engine head problems, please tell us after draining the radiator, what does the coolant resemble ............... and more importantly, what does the tops of the radiator tubes look like .......

4. Step (2) in the right direction is important.

[Dick Steinkamp]

Originally Posted by H. L. Chauvin

"The radiator has .......... "always" ........... overflowed a bit."

I think this could be because many Model A owners overfill the rad.

[RawhideKid]

Hey, how about turning the GAV all the way clockwise til it stops, then turn it open ½ turn?

Run it like ya stole it and see if that helps, but be sure that the water level is about 2" down from the top of the neck.

My wooden nickle worth.

[Jim/GA]

Originally Posted by H. L. Chauvin

Mike,

1. Every time an 86 year old block with an 86 year old radiator overheats, the most likable cause is usually what nobody likes to even whisper in the dark, at midnight, in the middle of a dense jungle; i.e., the "R" word.

2. You said it ran flawlessly; however, your one (1) hint mentioned is leaning towards a distinct cause of overheating and appears to be possibly getting close to whispering the "R" word: "The radiator has .......... "always" ........... overflowed a bit."

3. If not a malfunctioning thermostat as mentioned above, rather than take off to Mars with engine head problems, please tell us after draining the radiator, what does the coolant resemble ............... and more importantly, what does the tops of the radiator tubes look like .......

4. Step (2) in the right direction is important.

Go ahead and say it! RUST!!!

Some people are so sensitive!

.

[irex511]

I'm willing to try all of it. May have some time tomorrow evening after work so will keep you all posted...

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