1935 Ford radiator

[Tom Z...]

I had my 35 Ford radiator recored. Question is: should I use a pressurized cap or put the original cap with the wire bail on it? I am using a 59AB flathead in the car. Do these engines run cooler when the radiator is pressurized? Thanks Tom Z...

[40cpe]

Typical advice is not to run more than a 4# cap on the old radiators unless the tanks have been reinforced to handle the extra pressure. I put a 4# on my '38 and could hear the upper tank pop when the tank oil canned, and then hear it again when it cooled off. I took the pressure cap off.

I think the only reason a pressure cap will help it to run cooler is it might prevent some coolant loss from overflow and retain more coolant in the radiator.

[FL&WVMIKE]

[QUOTE=40cpe;874460]Typical advice is not to run more than a 4# cap on the old radiators unless the tanks have been reinforced to handle the extra pressure. I put a 4# on my '38 and could hear the upper tank pop when the tank oil canned, and then hear it again when it cooled off. I took the pressure cap off.

I think the only reason a pressure cap will help it to run cooler is it might prevent some coolant loss from overflow and retain more coolant in the radiator.[/QUOT

Under a pressurized system, it takes a higher temperature to make water boil.
MIKE (mikeburch)

[s55mercury66]

[QUOTE=FL&WVMIKE;874580]

Originally Posted by 40cpe

Typical advice is not to run more than a 4# cap on the old radiators unless the tanks have been reinforced to handle the extra pressure. I put a 4# on my '38 and could hear the upper tank pop when the tank oil canned, and then hear it again when it cooled off. I took the pressure cap off.

I think the only reason a pressure cap will help it to run cooler is it might prevent some coolant loss from overflow and retain more coolant in the radiator.[/QUOT

Under a pressurized system, it takes a higher temperature to make water boil.
MIKE (mikeburch)

It also helps to squeeze coolant into areas that are normally air pockets in the cooling system.

[Uptown83]

im using my original radiator in my 35 with an 8ba. I have a non pressurized cap on it. I dont have many miles on it though but everything is working fine.

[G.M.]

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[QUOTE=s55mercury66;874601]

Originally Posted by FL&WVMIKE

It also helps to squeeze coolant into areas that are normally air pockets in the cooling system.

The boiling point has nothing to do with this problem An old Ford should never get to 212 degrees so where does this boiling point factor come in??. The purpose of the pressure cap or Skips 3 lb valve is to close the over flow tube so water can be forced through the radiator tubes which act as a restriction. The cap or valve is also a safety device that opens from pressure to protect people and the system. G.M.

[Old Ford Addict]

I had a nice 35 rad for mine put together from two I had that needed work.
I had the stock cap location filled / plugged and had a 90 degree neck for modern cap put on.

[rheltzel]

FL&WVMike has it right...a pressure cap won't help the engine run cooler; quite the opposite: it will allow the engine to run HOTTER before the coolant boils. Better to follow G.M.'s advise and find out what's wrong if the temp routinely gets to 212.

[blucar]

Actually, how hot the engine runs, with certain limitations, is not a big deal, the loss off coolant is the thing that should be avoided..
Modern engine oil is designed to with-stand high temps.. A fifty-fifty mixture, water and coolant, will generally have a boiling point of approximately 230 + degrees.. For every pound of pressure supplied via a pressure type cap, the boiling point is raised 3 degrees.
Modern engineering has proven that the higher the temps an engine is ran, provides greater engine performance and longevity.
Prior to the invention of coolant recovery tanks and pressure caps, the big problem was overheating due to coolant loss and/or air entrapment within the cooling system..

[FL&WVMIKE]

[QUOTE=G.M.;874795][QUOTE=s55mercury66;874601]

The boiling point has nothing to do with this problem An old Ford should never get to 212 degrees so where does this boiling point factor come in??. The purpose of the pressure cap or Skips 3 lb valve is to close the over flow tube so water can be forced through the radiator tubes which act as a restriction. The cap or valve is also a safety device that opens from pressure to protect people and the system. G.M.[/QUOT

You say, "an old Ford should never get to 212 degrees". I have seen several old Fords, over 212 degrees. S**t happens !
Be sure to clean out Skip's overflow valves, ever so often. If you have any crud in your cooling system, it will eventually get into the valve and plug it up. Be sure to keep it clean.
MIKE (mikeburch)

[Talkwrench]

If you don't have any problems with your cooling system, and should be far better if your radiator has been done just put that standard non pressurised cap back on and don't worry about it..

[Straightpipes]

My 35 runs fine with the original non pressurized system. Radiator is clean and I spent many hourts cleaning all of the junk out of the block when I built it. If the timing is right it shouldn't overheat under normal driving conditions.
I ran it all this week. It runs up to 165 thermostat temp and stayes right there.