Farmall h and m radiator cap question

rankrank1 · Jun 19, 2013

What are you all running for radiator caps on Farmall h's and Farmall m's? (Pressurized cap or non-pressurized?)

Background: I have both a 1951 Farmall h and a 1946 Farmall m. Was thinking about replacing the radiator caps on both tractors as they are both in sad shape.

The IH parts books show that both a Non-Pressurized cap was used on early models and then later a pressurized cap was offered as an option. While it does sorta break it down by serial number with recommendations; I am not sure that will help me. I believe my h to be mostly stock and original (do not know for sure though), but I believe the m may have had some things changed on it over the years so serial probably irrelevant on it.

Anyway, What you all running for radiator caps. (FWIW: My m has a non-pressurized cap full of pin holes and my h has a pressurized cap but it is missing half the rubber gasket so it is essentially non-pressurized).

FBH44 · Jun 19, 2013

I replaced my 1950 "H" cap [with the out-to-the-side-lever ] with another one off eBay. Spring-loaded, holds a rubber/brass end down into the radiator opening. I was sceptical of it, it didn"t seem like it had much pressure to it, but it holds just fine.

CNKS · Jun 19, 2013

The cap depends on the radiator, a pressurized cap will not fit a non-pressurized radiator and vice versa. The early models of both tractors had non-pressurized radiators, later models pressurized. Replacement radiators are pressurized. Thus the pressurized cap was not an option, as such. You buy the cap that fits the radiator.

rankrank1 · Jun 19, 2013

(quoted from post at 02:39:37 06/20/13) The cap depends on the radiator, a pressurized cap will not fit a non-pressurized radiator and vice versa. The early models of both tractors had non-pressurized radiators, later models pressurized. Replacement radiators are pressurized. Thus the pressurized cap was not an option, as such. You buy the cap that fits the radiator.

That is excellent information and sorta the answer that I was hoping to hear. If the caps will not interchange then impossible to buy the wrong one. Buying the one that fits the radiator makes sense.

Owen Aaland · Jun 19, 2013

The non pressurized cap fits the radiator neck much like the fuel cap and looks very similar to the early fuel caps.

Dan T in MO · Jun 19, 2013

My old cap came off in 3 pieces. Folks at the local NAPA store looked in their book and said my H calls for a 4 pound cap, but the only cap they had was 7 pounds. Well, it fits and after replacing the cap, all the hoses and a bottle of stop leak, I finally got it holding water.

John M · Jun 20, 2013

Easy way to explain it, if its pressurized, the cap secures on the outside of the neck, non pressurized secures to the inside of the neck. 99.9% of the non pressurized Ive seen have WATER on the cap. Pressurized, if origianl, have a "wing" on it, as it was called.

Southern Ray · Jun 20, 2013

My M has a non pressurized cooling system.

I put a 2 1/2" rubber Fernco cap on it.
works nice.

Farmall h and m radiator cap question

rankrank1

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FBH44

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CNKS

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rankrank1

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Owen Aaland

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Dan T in MO

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John M

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Southern Ray

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