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View Full Version : pressure in radiator when vehicle has not been run


jason74
04-25-2011, 03:22 PM
I have a 406 chevy small block with a 350 turbo trans in a 1986 elcamino SS. I drag race in the 1/4 mile runs 11.70. I am having a problem with my radiator building pressure and going back into the recovery jug. I have no water in my oil, no water in the cylinders. I have flushed the radiator and put only water back in it and it has not changed anything. I have changed the radiator cap and still no luck. I can leave it sit after letting the pressure out and it will build it right back even if it has not been ran. CONFUSED PLEASE HELP!!!!!

TopspeedLowet
04-26-2011, 02:55 AM
The pressure you are getting is likely an air pocket in the head that was there when you shut down the engine and is trying to get to the radiator or where ever your cap is. You may have a poorly designed system that is putting air in because it is not completely full when running or you never got all the air out when you filled it this spring. You could also be running high temperatures and boiling the straight water mixture if you have a thermostat in it allowing 212 operating temps. To get air out of the block if that is the problem, jack the car up in front to make the cap the high point and turn on your pump if it is electric. If it is belt driven you have to start the car. I hope this helps you solve or find problem.
Bruce

fast75vega
04-26-2011, 04:11 AM
The pressure you are getting is likely an air pocket in the head that was there when you shut down the engine and is trying to get to the radiator or where ever your cap is. You may have a poorly designed system that is putting air in because it is not completely full when running or you never got all the air out when you filled it this spring. You could also be running high temperatures and boiling the straight water mixture if you have a thermostat in it allowing 212 operating temps. To get air out of the block if that is the problem, jack the car up in front to make the cap the high point and turn on your pump if it is electric. If it is belt driven you have to start the car. I hope this helps you solve or find problem.
Bruce

X2 :wink: