Cooling Issue? how to proceed

[SoCalCoupe]

Not sure what's the best course of action or how concerned to be.


! have a stock 1941 Special Coupe with a 221 or 239 V8 that I've had for just a few months. After warming up, the stock temperature gauge will go to 3/4 or 7/8 hot, especially when sitting at a stop light. Within a minute or two, it will go to 1/2 hot or normal temperature. It then cycles for the rest of the drive between 7/8 and 1/2. That indicates to me that a thermostat is opening and closing. Of course I don't think much of the stock temperature gauge. I'm pretty sure the thermostats are seeing a different temperature than the temperature gauge sensor since they're not located together.


No other symptoms. Car seems happy. No steam or overflow. No coolant leaks. Coolant looks good, green for ethylene glycol. Oil looks good, no coolant contamination.



Should I be concerned about this? Am I going to hurt the engine? Should I remove the thermostats? I live in a really mild climate, San Diego. Doesn't get too hot or too cold.


Before I do that, should I get a mechanical temperature gauge to get a better feel for what's really going on?

[51 MERC-CT]

Until you can determine what actual temps. are, things sound normal to me.

[Brian]

No other symptoms. Car seems happy. No steam or overflow. No coolant leaks. Coolant looks good, green for ethylene glycol. Oil looks good, no coolant contamination.



If it ain't broke, don't fix it! enjoy!!

[Tinker]

San Diego. I might venture to say you don't need temp stats. They are used to run cold motors up to temp in cold weather. Oh course you might have other issues too.

[koates]

You could buy yourself an electronic temperature laser pointer gun and just point it at different parts of the cooling system whilst on your travels. This will give you a very good idea of whats going on. Regards, Kevin.

[Alaska Jim]

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What Koates said

[CA Victoria]

Living JNO you in similar weather conditions the temperature in my sedan will run 165-175, as warmer weather arrives on a hot day it will peak at 195.
I installed SW wings temp and oil pressure gauges that look right at home so I can drive with peace of mind. Not sure who makes them but I’ve seen small magnetic temp gauges too.

Also, if you consider flushing your cooling system I recited my recent experience here in post #12: https://www.fordbarn.com/forum/showt...hlight=Cooling

[SoCalCoupe]

Originally Posted by koates

You could buy yourself an electronic temperature laser pointer gun and just point it at different parts of the cooling system whilst on your travels. This will give you a very good idea of whats going on. Regards, Kevin.

Well, that sounds practical. I have something similar on my new Fluke, contact, not laser pointer.

[mcgarrett]

Many of the old-timers will tell you that if a car isn't spitting water out the radiator overflow tube, it isn't overheating. If it were, you would hear boiling and gurgling from inside that radiator when you shut the car off after reaching full operating temperature - and you would see water/coolant on the ground. I also know from experience that my flathead will spit out any excess water it doesn't need. I have a temp gauge that tends to run on the high side too, but never expels any water out the overflow even on really hot days in Texas.

[Fritz]

I would also venture to say you don’t need the thermostats. It is normal for the engine to get warmer like that in warm weather at a light. My stock gauge is consistent. I use the laser temp gun pointed at the heads and block to determine the actual temp the stock gauge is reading at. If you’re not going much above 200, you’re all good.

[Lawrie]

?t/stats, I have them in my 33, stock 75c ones from the store ,tig welded to a short length of SS tube pushed in the hoses, just the other day we did the day in 39c at 50 mph towing and engine only got as hot as about 88c on some long pulls on the hills.
I would not run my 33 with out them.
Lawrie

[38 coupe]

Two points:
1 - Ford installed thermostats from the factory. Ford was good at not spending money if it wasn't needed. Personally I like 180 F units in 8BA engines and 160 F in pre-war cars like the 32-38 cars where the fan doesn't cover as much of the radiator.
2 - 3/4 hot on a factory Ford gauge, assuming it is working correctly, is 180 F.

[john worden]

FWIW Over several decades in the restoration business I've heard people much older and with personal experience owning, restoring, and hot rodding flat head V8s say that they run hot. It was said as a matter of fact without panic. A cure was never offered or recommended other than adequate cooling system maintenance.
I've owned a customized 51 Lincoln w/the stock 337 cu. in. flathead V8 for about 10 years now. The temp. rises and falls fairly quickly depending on ambient temp. and road speed.
It previously lived in Tucson Ariz. and the owner (Charlie Hall) fitted a sender and temp gauge for each head. It also saw duty towing a car trailer!
Remember that the exhaust heats quite a bit of the block internally in side valve engines.
Hot is normal in the flatties. Drive it.

[mfirth]

What 38 coupe said works for me.

[RKS.PA]

Brad, I put a mechanical Stewart Warner temperature gauge in my '47 just to keep and eye on the dash gauge. It turns out the dash gauge works fine, but it good to have a "second opinion"!

Temperature Gauge.jpg

[Lanny]

Originally Posted by 38 coupe

Two points:
1 - Ford installed thermostats from the factory. Ford was good at not spending money if it wasn't needed. Personally I like 180 F units in 8BA engines and 160 F in pre-war cars like the 32-38 cars where the fan doesn't cover as much of the radiator.
2 - 3/4 hot on a factory Ford gauge, assuming it is working correctly, is 180 F.

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X's 3 Don't leave home without them !




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[aussie merc]

good idea better if you have stock one in one head and the add on one in the other you will see a slight difference as thermostats don't come in matched sets . and to those that say you dont need them Bu----it because if you didnt need them i can ensure you Henry wouldnt have fitted them in any form .Trust me they do so much more that just control the temps

[tubman]

Add another vote to the pro-thermostat crowd. Removing them to combat a cooling problem is a band aid at best and a path to contaminated oil (from running too cold) at worst.

[Tinker]

Originally Posted by RKS.PA

Brad, I put a mechanical Stewart Warner temperature gauge in my '47 just to keep and eye on the dash gauge. It turns out the dash gauge works fine, but it good to have a "second opinion"!

Attachment 486037

Make sure to put a infrared temp gun on it to check the SW. I have newer units and they are off 20 degrees.

[Tinker]

Originally Posted by tubman

Add another vote to the pro-thermostat crowd. Removing them to combat a cooling problem is a band aid at best and a path to contaminated oil (from running too cold) at worst.

When I lived in florida it was never cold, in Minnesota they make sense now.

Ford sold cars/trucks everywhere. Not sure they knew where they where always going. So they put stats in all of them. Probably also why early volvo's in cold climates didn't have good ac either.

I do agree that thermostats won't fix a cooling issue, Nor suggested so. But won't hurt a high heat situation in a very warm climate. Granted if you live in a certain climate that might start with a motor already at 70-80 degrees. I'm in neither crowd.


While we are at it. Take over the kitchen and use a pot of water with a cooking thermometer. Drop your thermostats in prior to their opening temp. See if they open at the desired temperature. Best of luck!



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