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Posted by Chris Case @ San Diego on Friday, January 18, 2008 at 00:52:09 :
In Reply to: Re: Blew a freeze plug today! Heard it hit the fender. posted by D. Sherman on Friday, January 18, 2008 at 00:21:31 :
If there is no way out, you will build up pressure in the block. How much depends on the pump design.
Some pressure is good, it prevents hot spots from making steam pockets. Boiling point goes up with pressure at the rate of 3 degrees per pound of pressure. Steam pockets don't absorb heat like liquid water does, so those areas would get even hotter. I recollect desirable block pressure is about 5-10 psi. A 1 5/8" core plug has two square inches of area, so only ummm 20 pounds trying to push it out.
My truck has a non-pressurized cap on it, the only pressure against the plugs is from the pump.
Hmmm, now I wonder about that small hole in the back of the water pump plate. About 5/16", and away from the out put part of the pump. Bypass port, perhaps? Plugged up, perhaps? PITA to pull a pump just to look at that. Maybe I ought to conceptualize my spare pump a bit...
I guess I will rig up a block pressure gauge tomorrow.
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