7 lbs Radiator cap help?
Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,809
Likes: 0
7 lbs Radiator cap help?
The guy at the parts store said that going from a 16 lbs cap to a 7 lbs cap help the engine run cooler due to less pressure.
Is this true?
Plus being so smart I bought one before checking with the forum. :rolleyes:
[Modified by Tominator, 3:13 PM 4/21/2003]
Is this true?
Plus being so smart I bought one before checking with the forum. :rolleyes:
[Modified by Tominator, 3:13 PM 4/21/2003]
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: 7 lbs Radiator cap help? (Tominator)
Pressure has absolutely nothing to do with how cool the engine runs, Only the temperature at which the water/coolant boils. Pressure only builds as the temperature rises.
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: 7 lbs Radiator cap help? (Tominator)
Tominator:
If your radiator and heater core can take it go with the largest pressure cap it will allow. I'm running a Moroso 19-22lb radiator cap with my Be Cool aluminum radiator. The only thing a smaller pressure radiator cap will do is allow the coolant to boil out into your overflow at a lower pressure.
If your radiator and heater core can take it go with the largest pressure cap it will allow. I'm running a Moroso 19-22lb radiator cap with my Be Cool aluminum radiator. The only thing a smaller pressure radiator cap will do is allow the coolant to boil out into your overflow at a lower pressure.
Le Mans Master
Joined: Apr 2000
Posts: 5,202
Likes: 10
From: cincinnati ohio
St. Jude Donor '09
Re: 7 lbs Radiator cap help? (Tominator)
I always run a 7 lb cap and let it be the weakest link in the cooling system chain. My motor runs a steady 180 and rarely if ever :U s coolant.
But no a lower pressure cap won't lower engine temps...
Mike
:cheers:
But no a lower pressure cap won't lower engine temps...
Mike
:cheers:
Melting Slicks
Joined: Aug 2000
Posts: 2,310
Likes: 1
Re: 7 lbs Radiator cap help? (Tominator)
Since temperature and pressure are directly proportional, an increase in temperature will cause an increase in pressure (that's why you don't try to remove the radiator cap when the coolant is hot).
So, if you start letting the coolant boil-off/vaporize at 7 PSI, I would think that what stayed behind would be cooler than what it would be at 16 PSI. But, eventually you wouldn't have enough coolant in the system to keep the engine cool. That is, the coolant might not be geting any hotter than what is required to vaporize it at 7 PSI, but everything around it (namely the engine) would be getting much, much hotter.
Of course I could be waaaaay off. It's been about 25 years since my last physics class.
So, if you start letting the coolant boil-off/vaporize at 7 PSI, I would think that what stayed behind would be cooler than what it would be at 16 PSI. But, eventually you wouldn't have enough coolant in the system to keep the engine cool. That is, the coolant might not be geting any hotter than what is required to vaporize it at 7 PSI, but everything around it (namely the engine) would be getting much, much hotter.
Of course I could be waaaaay off. It's been about 25 years since my last physics class.
Advanced
Joined: Jan 2002
Posts: 87
Likes: 0
From: BOULDER CREEK ca
Re: 7 lbs Radiator cap help? (Tominator)
temperature and pressure are proportional. its 3 degrees for every pound of pressure. So a seven pound cap is going to relieve when it sees 233 degrees(212+ 21). I have a '52 panel truck(running a 350 chevy) that I have to run a seven pound cap on because the 50 year old side tanks of the radiator would burst before I could hit 15 lbs of a conventional radiator cap. So when i take in camping after climbing a grade and stopping, the relief will blow coolant into the overflow tank( it used to blow it on the ground before in put in the overflow) however running around during normal weather is not a problem. It just runs hot in the summer because I'm asking a small block 350 to haul around an 8000 lb truck.
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