Radiator cap pressure
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Elder User
Joined: Oct 2008
Posts: 556
Likes: 1
From: Prescott, AZ
Radiator cap pressure
I didn’t want to hi-jack a thread on cooling but it raised a concern about radiator caps.
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I believe that raising the pressure of the cap can help reduce water temperature but I did not know the reason for the various cap pressures.
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I have the old stock radiator with the big brass tank. The old radiator cap went bad and I replaced it with a 13 lb cap that I had from old parts. Soon after installing, I noticed a leak. It turns out to be a split in the brass tank. I was able to repair the split and but didn’t dwell on the cause.
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F6Guy posted that you should not use a high pressure cap on the large brass tanks.
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The 13lb cap is awaiting destruction upon your confirmation.
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I believe that raising the pressure of the cap can help reduce water temperature but I did not know the reason for the various cap pressures.
<o></o>
I have the old stock radiator with the big brass tank. The old radiator cap went bad and I replaced it with a 13 lb cap that I had from old parts. Soon after installing, I noticed a leak. It turns out to be a split in the brass tank. I was able to repair the split and but didn’t dwell on the cause.
<o></o>
F6Guy posted that you should not use a high pressure cap on the large brass tanks.
<o></o>
The 13lb cap is awaiting destruction upon your confirmation.
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Senior User
Joined: Nov 2007
Posts: 494
Likes: 1
From: Guelph
For every pound you increase in pressure it raises the boiling point 3 degrees of water temp.So you may not boil over but you put alot more stress on these old rads. I would go down in presure to save the rad.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
Hi Edzakory,
Yep, like we discussed in the other thread and REG1952 mentioned there's a bell curve here - not enough pressure, over heat and boil over - too much pressure - blown seams. It's hard to find the top of the curve sometimes. I guess that's one of the reasons I have the radiator and the (despite the "off" function I'll use the "politically correct term") surge tank with different ratings of caps.
13 pounds blew my seams too and I don't have a stock radiator. So I went to 7 pounds and still had a problem. But my system is designed and configured differently to handle quick heating as I explaned over there.
Try the 7 pound cap and it should be ok. If not you can go to 4 pounds and raise the % of coolant to water in your mixture by 15-25%. It probably wouldn't hurt you to try that anyway out there in AZ.
Ok that's all I'm saying - tee hee!
J!
Yep, like we discussed in the other thread and REG1952 mentioned there's a bell curve here - not enough pressure, over heat and boil over - too much pressure - blown seams. It's hard to find the top of the curve sometimes. I guess that's one of the reasons I have the radiator and the (despite the "off" function I'll use the "politically correct term") surge tank with different ratings of caps.
13 pounds blew my seams too and I don't have a stock radiator. So I went to 7 pounds and still had a problem. But my system is designed and configured differently to handle quick heating as I explaned over there.
Try the 7 pound cap and it should be ok. If not you can go to 4 pounds and raise the % of coolant to water in your mixture by 15-25%. It probably wouldn't hurt you to try that anyway out there in AZ.
Ok that's all I'm saying - tee hee!
J!
