Chris Haynes
Well-known member
My engine has an OHV head, leakless water pump, fresh rebuild. I had a new core put in the radiator and it is now pressurized. The radiator cap the shop supplied is a 14 pound cap. Will that be a problem?
radiator pressure
- Thread starter Chris Haynes
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Big hammer
Well-known member
You may need a recovery/expansion tank ?!
Kurt in NJ
Well-known member
The upper tank on a stock radiator is not reinforced or shaped to be a high pressure system
woofa.express
Well-known member
I replaced the old radiation in my 28 ute with a pressurised one plus a pretty posh overflow tank which I purchased from Snyders; I don’t recall the manufacturer. I had an engine full of vinegar to clean out the block and it boiled and shot out the radiator cap. It spoiled my nice maroon paintwork, bugger The cap had failed; it came apart- (no criticism of the supplier intended). purchased a 4psi from the local general auto parts supplier and the problem is possibly resolved. Did I do the best thing in going pressurised? The dury is still out.
Chris Haynes
Well-known member
Unfortunately my filler neck is much smaller than that. Most likely from a Japanese model.
Joe K
Well-known member
By increasing the pressure 4.5psi, you raise the temperature where a "boil over" can occur. (i.e. from 212 to 258F) It can increase the rate of heat transfer between radiator and air effectively giving your cooling system a bit more heat transfer capacity IF you're at boil over temperature. Heat transfer CAN increase to the difference between ambient (say 70F) and either 212 (142t) or 258 (188t) or roughly 1/4 improvement.
MOSTLY engines operate considerably under the water saturation temperature. Think 180F max. Boil over occurs when for some reason heat transfer is impeded AT THE RADIATOR. Generally if you're at that point, going up 46 degrees in coolant temperature probably won't save you. Resistance to heat transfer is resistance.
Joe K
MOSTLY engines operate considerably under the water saturation temperature. Think 180F max. Boil over occurs when for some reason heat transfer is impeded AT THE RADIATOR. Generally if you're at that point, going up 46 degrees in coolant temperature probably won't save you. Resistance to heat transfer is resistance.
Joe K
Randy in ca
Well-known member
Joe I think you need to check your numbers - charts I've seen many times indicate that a 4 psi in pressure will only increase straight water to a boiling point of 225 degrees, not above 250. 16 psi only raises water boiling temp to 252 degrees. The addition of "antifreeze" adds significantly to the boiling temperatures under all pressures. Using a 50% solution raises the boiling point more than a 4 psi of pressure increase would.
The most significant result of increasing pressure in any cooling system is the subsequent increased likelihood of creating leakage.
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Joe K
Well-known member
Joe I think you need to check your numbers - charts I've seen many times indicate that a 4 psi in pressure will only increase straight water to a boiling point of 225 degrees, not above 250. 16 psi only raises water boiling temp to 252 degrees. The addition of "antifreeze" adds significantly to the boiling temperatures under all pressures. Using a 50% solution raises the boiling point more than a 4 psi of pressure increase would.
The most significant result of increasing pressure in any cooling system is the subsequent increased likelihood of creating leakage.
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You may be right. I got lazy and googled "water temperature for saturation pressure of 18.5 psia."
Google may have gotten confused between PSIA and PSIG (gauge pressure)
Your table DOES seem to show percentages mix with anti-freeze - which WILL affect the boiling temperature as you see. I'm talking pure water (top line on chart) - a singular breed of cat.
Keenan and Keyes (Steam Tables) would be a more accurate source.
I'm showing my "engineering age" here. Like "reverse polish" calculators.
The HP-45 DID put man on the moon. Ha, ha. Google AI disputes...
Google AI had to reach pretty far on an obvious overstatement. Spock would laugh.
Joe K
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katy
Well-known member
Ditto