Coolant pressure
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Instructor
Joined: Apr 2007
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Coolant pressure
My 84 seems to build alot of pressure when I first start it. When it sits cold (over night) and I start it, the upper radiator hose seems to go from little or no pressure to almost rock hard in 3-5 minuts. Is this normal? Car runs 220-235 in idle traffic, 195-200 running down the interstate.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Your temps are normal. At highway speeds you are bumping off the stock thermostat rating. That demonstrates that the radiator is doing it's job. I can't imagine why pressure builds so fast. You could pressure check your cap to make sure it bleeds off pressure above it's rated 15 - 17 psi rating. If it sticks closed and allows too much pressure to build, something like a hose, could blow.
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
The pressure SHOULD be a function of temperature. Three to five minutes from a cold start doesn't make sense. Have you burped it? Got all of the air out of the cooling system? The hose might be soft, cold, because of air, and then hardening up once started and the air is dispersed. (Clutching at straws, here.) You could pressure check the cooling system for a better idea of what, exactly, is happening.
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Thread Starter
Instructor
Joined: Apr 2007
Posts: 215
Likes: 1
Yea I got a new radiator, t-stat, all coolant and heater hoses, and made sure the coolant cycled after filling it and running it till the coolant cycled in the radiator, then capped the radiator with a new 15 pound cap. I have put about 1,000 miles on the car. Runs great, couldn't be happier with the performance. I guess I need to pressure test the system. Where can I get a pressure tester? Inexpensive perferably.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
That description doesn't say if you have eliminated all the air in the cooling system. Any parts store should have a cooling system pressure tester. Some may have one on a free "rental".
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