Higher pressure radiator cap?

[Johnny248]

I've seen these "high performance" radiator caps, that are a high pressure than standard caps. They claim you should run the highest pressure cap that your radiator is able to withstand. I guess the theory is high pressure allows a higher boiling point which transfers heat better?? I don't know, I did two searches and could not find any info.

Any truth to this stuff?

 

[Drew99GT]

Those are normally used in racing applications where antifreeze is not allowed. Helps prevent boil overs, but can seriously lead to leaks.

 

[c3po]

A higher pressure radiator cap will just raise the boiling point, and on an older engine using one can lead to problems.

 

[Chris142]

You want the lowest pressure that you can run w/o having the water pushed out.

An engine is say 220 degrees with a 7 lb cap or a 20 lb cap.

With a higher pressure cap the engine will throw up coolant at a higher temperature but what good is having a boiling temp of 280 if your heads cracked @ 260?

The less pressure you run the longer hoses and gaskets will last.

 

[eljefino]

Originally Posted By: Johnny248
I guess the theory is high pressure allows a higher boiling point which transfers heat better?? I don't know, I did two searches and could not find any info.


If you run less AF and more water it transfers heat a little better... IMO if you do this you should set the fan to come on sooner...

 

[mechanicx]

One thing is a higher prssure cap will prevent steaming and boiling pockets at hot spots better. If you buy a new AC Delco cap a lot of times they give you an 18psi to replace your old 15psi. I don't think I'd want to go higher than 18 psi.

 

[Johnny248]

ok, so I guess all I want to know is it a good idea to put a high pressure cap on a sound cooling system?

 

[mechanicx]

Yes, like I said it helps prevent any steam pockets forming at hot spots, but there's really no need to go over 18 psi.

 

[Johnny248]

My service manual first says when testing system for leaks, install tester and apply 23psi into the system. Therefore, I would thing it would be safe for anything up to 23psi?

Next, for the radiator cap it states Minimum limit, 12psi standard value 14-18psi. That being said, I'm not sure what the cap is actually rated at. According to Stant, is requires a 16psi cap.

So, should I put an 18psi cap on?
BTW, I have Honda Type 2 coolant in there, I'm sure it makes no difference.

 

[Chris142]

Originally Posted By: Johnny248
ok, so I guess all I want to know is it a good idea to put a high pressure cap on a sound cooling system?
Do you want your plastic radiator tanks holding back 18lbs of pressure?

 

[Johnny248]

Originally Posted By: Chris142
Originally Posted By: Johnny248
ok, so I guess all I want to know is it a good idea to put a high pressure cap on a sound cooling system?
Do you want your plastic radiator tanks holding back 18lbs of pressure?


I don't know? my manual says standard value is 14-18psi, so I guess an 18psi cap would up that to 16-20psi?

 

[mechanicx]

An 18 psi cap would only increase pressure 2psi over a 16 psi cap. Your application says up to 18 psi is fine. I would run either a stock cap or up to 18 psi. A high pressure cap might slightly decrease the service life of your hoses, very slightly.

 

[Johnny248]

All of the caps I am seeing are 1.3 or 19psi, is that fine?

 

[Chris142]

I dont run over 16 lbs on my stuff. I try to stick with 13.My pickup has a 7lb cap. My peterbilt os a no pressure system.

 

[mechanicx]

Originally Posted By: Johnny248
All of the caps I am seeing are 1.3 or 19psi, is that fine?


Yes either is fine. If you get an OEM one my guess is it would probably be 16 psi, maybe 18psi. The thing is just because you put a 18 or 19 psi cap on, it's only going to run at that max psi rating if your coolant is full enough and you are at full operating temperature.

 

[Dualie]

All of my trucks run 7 PSI caps and my gassers run 13lbs. less pressure = less stress on all the gaskets and parts.

 

[Gary Allan]

The OEM for my jeeps is 18psi. Oddly, I've never had a hose failure ..but have had to replace both caps. I did have the seam leak on the wife's rad. I bought one of the out of vogue all metal rads with multiple cores. Actually I had it sitting around waiting for one of the OEM's to have an issue.

 

[Steve S]

Use the factory recommended.

 

[ATS-V]

Where can you find lower pressure caps?

My OEM cap is 16 lbs, I would like a 8-12 lb cap but at AutoZone I got the blank stare.

 

[mechanicx]

Originally Posted By: 97 GTP
Where can you find lower pressure caps?

My OEM cap is 16 lbs, I would like a 8-12 lb cap but at AutoZone I got the blank stare.

I don't recommend going lower than stock, but I'm thinking maybe if you looked on Stant's site and found the part number for an 8-12 psi cap that fits your application, then you could search around for who has that part number. I'm sure Stant probably has a lower psi cap that fits your application if anybody does.