Question: 1940 Ford Radiators.

[Mart]

Hi.
The radiator in my 1941 pickup originally came from my 1940 Ford coupe.

It has a pressurised cap.

I have seen photos of a vent located top center of the top tank. Mine does not have this.

So my question is:

Are 1940 radiators normally pressurised? Or are they normally non pressurised and the overflow tube is located in that vent piece at the top?

I have a problem with the top tank balooning up. One of the seams has split which I presume is from fatigue due to the movement that happens when it baloons up.

If it is supposed to be non pressurised I might rework it to have a vent top dead center.

Thanks in advance.

Mart.

[alanwoodieman]

49 Fords as most of the 30's and 40's cars/trucks were non pressurized. what pressure cap are you using? 4lbs is about right as it appears your rad has already been converted to a pressure system. still there needs to be a way for the cap to vent out the overpressure and water overfill

[alchemy]

Even with a new Walker radiator I only use a 7 lb cap on my flathead. If I had an original radiator I'd probably stay at 4lbs. The neck will need to be modified/replaced to accommodate the pressure cap.

[deuce_roadster]

40 definitely non pressurized. If it was a 40 radiator, it should have a 91A on the back side of the top tank and cap on angled part, not top. IF pressurized, was done at a later date.

[mcgarrett]

Flathead radiator upper and lower tanks did not have the necessary built-in reinforcement to withstand any pressurization.

[hotrodA]

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I have a 40 radiator that I had radiator shop add two internal braces fabbed from sheet brass inside the tanks to stop the ballooning.

[flatjack9]

Actually a 40 would have an 01A embossed in the top tank. Physically it is the same as a 39 or 41.

[Newc]

Hi; I found the pressurized rads cooled about 10 degrees better in my stock forty. 4 lb cap. changed to a correct rad for judging and noticed the difference. Newc

[rotorwrench]

The 41A-8100-A & B caps were a product that came out at the close of WWII. The post war cars were equipped with these. The 41A-8100-A/B cap was developed to retrofit back to 1938 on those radiators that had a bung that would work with it. Radiators so equipped would have been replacement parts made after the war with few exceptions.

[flatjack9]

Originally Posted by Newc

Hi; I found the pressurized rads cooled about 10 degrees better in my stock forty. 4 lb cap. changed to a correct rad for judging and noticed the difference. Newc

Why would a pressurized radiator make the engine run cooler?

[Kube]

Originally Posted by flatjack9

Actually a 40 would have an 01A embossed in the top tank. Physically it is the same as a 39 or 41.

Actually no, it would not.
A '40 Ford radiator has 91A embossed to the upper tank.
The cap is on the slanted end of the top tank.

A '41 radiator is (physically) nothing like the '39 or '40. Different size / different shape.
The cap is centered on the top.

[Kube]

Originally Posted by flatjack9

Why would a pressurized radiator make the engine run cooler?

As you surely know, it would not make an engine run cooler. I figured your question to be rhetorical - yes?
It would increase the running temperature of the system before it over flowed but again, it would not aid in running cooler.

[Mart]

Higher pressure makes the boiling point higher.
So higher pressure does not make it run cooler, it just raises the temperature it can run at before reaching boiling point.

I found the converse effect in a completely different scenario. On test at high altitude in Colorado. Lets bust out the travel kettle and make a nice cup of tea. It was a waste of time. you can't get the the water hot enough due to the lower air pressure.

I can see why lots of people are coffee drinkers.

mart.

[philipswanson]

Originally Posted by Kube

Actually no, it would not.
A '40 Ford radiator has 91A embossed to the upper tank.
The cap is on the slanted end of the top tank.

A '41 radiator is (physically) nothing like the '39 or '40. Different size / different shape.
The cap is centered on the top.

How is the shape different on a 41 radiator from a 40? I have a 41 radiator in my 40 wagon and it bolts in perfect with no interference. I know the filler neck is in the center on the 41 and not on the 40 but how is the overall shape of the radiator different??

[Mart]

Can I get a clarification on something. I just looked and most images of 1941 (emphasis on the 1) pickups show what appears to be a conventional looking cap top center of the radiator. Can anyone tell me if that cap is a pressurised cap or just a filler cap with no pressure mechanism??

Mart.

[Kube]

Originally Posted by philipswanson

How is the shape different on a 41 radiator from a 40? I have a 41 radiator in my 40 wagon and it bolts in perfect with no interference. I know the filler neck is in the center on the 41 and not on the 40 but how is the overall shape of the radiator different??

Taller and a bit narrower.
Think about this for a moment... IF they were the same, why would Ford have changed them for '41? Don't ya think they'd simply keep installing the 39/40 piece?

[rotorwrench]

They are very similar between 40 & 41 but not the same. The transition years always end up with odd stuff on them. Most 1942 stuff was carried over to the 1946 model year so there is a lot more similarity there. The radiators for the crankshaft mounted fan all had to work with it and Ford just had to have that hand crank available. A lot of aftermarket ones lost the crank hole for good reason. It was more expensive to double core a radiator than just make a simple single core set up.

Ford started out with the 4 lb pressure cap but quickly went up to 7 lb when the cars kept getting heavier. My old 51 Mercs run warmer than lighter cars even though they have a huge radiator. The 7 lb cap just allows it to run hotter without boiling the coolant out.

We drank a lot of coffee when I lived up in Colorado. Thank the Lord (and the radar experts) for micro wave ovens.

[flatjack9]

Originally Posted by Kube

As you surely know, it would not make an engine run cooler. I figured your question to be rhetorical - yes?
It would increase the running temperature of the system before it over flowed but again, it would not aid in running cooler.

Yes I do know. I was responding to Newc's post. He implied that the pressurized radiator cooled better. And it may have, but not because it was pressurized

[philipswanson]

Originally Posted by Kube

Taller and a bit narrower.

If it is narrower, how come it bolts in with the same feet?

[Kube]

Originally Posted by philipswanson

If it is narrower, how come it bolts in with the same feet?

A BIT narrower.