What else causes excess pressure in radiator?

RonA

RonA

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Feb 26, 2008
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My coolant pressure slowly goes up to 16psi and stays there till it cools back off. No oil in the coolant, no coolant in the oil. The only coolant loss i've found is around one of the upper radiator hose clamps. Been doing this for a couple of months now( I rarely drive it). I'm tempted to just pull the head and change the gasket, but i would hate to go to the trouble and find it's something else. Motor is out of a 2002, oringed and studded. Gasket is about 2 years old, maybe 10 k miles.

Thanks.
 
isnt that normal tho? our fords do it..


yes i know i said fords. but our other cars as well that builds pressure up in the rad hose.
 
I had it tested and he said it was going up to 16psi and staying there. Doesn't blow out, but the upper hose is pretty firm(more so than it used to be).
 
Have you replaced the radiator cap yet? They are supposed to regulate pressure, with this engine it should be about 12-14PSI if memory serves me correct.
 
i do know when my obs ford had a bad hg, it pressurized the cooling system and always puked it. i think i went through a gal a day if i drove it.
 
Put an emission probe in the radiator if it detects hydrocarbons it could be a hg. Maybe that bad clamp is letting air in? I would go with a cap first.
 
Is the overflow bottle full or empty? If its empty, then definately a HG, if it isn't empty....hmmmm?? Guess it could still be the hg, but if it doesnt blow the overflow empty, it isn't leaking bad.
 
Uh. When the coolant heats up it expands, causing the pressure. When it cools to ambient temp, it goes down in volume and the pressure goes down. What am I missing here?
 
I think you're just paranoid and need a new rad cap, but I did just finish replacing my gasket from doing close to the same. After a couple hundred miles, it would finally displace most of the coolant. I drove it this way for a bit, then it blew the upper rad hose off and I was left on the side of the road.
 
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