Radiator Cap

[Joe Flanagan]

Is the cap for our systems something that's readily available or is it a special order item? The guy at the radiator shop said I might have trouble finding a cap that's rated for 4 lbs. but I wanted to ask here.

[Plymouthy Adams]

don't overlook the TSC store as they carry caps for tractors etc and may have a matching cap..they do have 4 lb ers for Allis Chambers etc etc...

[aero3113]

I was able to find a cap no problem at my local auto store. I believe they are made by Stant.

[Joe Flanagan]

Thanks, Tim. I just ordered one at Auto Zone and it will be in tomorrow.

[Fireball]

What happens if one uses a higher rated modern cap with stock radiator?

[martybose]

What happens if one uses a higher rated modern cap with stock radiator?

One of two possibilities:

1. nothing

2. something leaks or gets blown out by the increased pressure

On some radiators it makes no difference, because the overflow doesn't go to the radiator fill.

Marty

[Fireball]

I was just wondering because my new combo contains modern engine but stock radiator, and I'm not certain which cap to use. I quess I'll try with the higher press modern style.

[Jim Saraceno]

I would think you would want to match your radiator, not your engine.

[BobT-47P15]

If you have this little raised item in the middle or somewhere on top of

your radiator with the overflow tube coming from it.....that's a zero

pressure deal. You don't need a pressure cap.

[Andydodge]

One other thing to look out for is that the pressure radiator caps usually have a different length between the cap and the rubber seal plus a different length spring...can't remember whether the older non/low pressure systems use the shorter or longer cap but there is a difference from what I've seen..............andyd

[Fireball]

Thanks guys! I'll keep the original then.

[greg g]

The cap doesn't really matter if you system is a 0 pressure radiator. As it is vneted below where the cap seals, the cap has no effect on the pressure. Didn't Mickey have a bunch of OEM/nos ones on epay???

If your radiator looks like the one Bob pictured, you can see the relief/overflow outlet is even with of below the cap.

[Fireball]

That's what I have fellows

[BobT-47P15]

Here's the non pressure cap....no spring at all.

Called "the classic", about $3 at my NAPA store.

Will probably have to order it in.