Is this normal? - Team Camaro Tech
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post #1 of 5 (permalink) Old May 4th, 07, 02:40 PM Thread Starter
Join Date: Feb 2001
Posts: 189
Is this normal?

I was timing my engine today and sience I didn't have a helper I was having to screw in the idle screw so that I could set a certain RPM to take readings from.

After timing the engine from 1000 - 3000 RPM in 500 RPM increments, I shut her down and she barfed (radiator overflow) on the driveway. My dual electric fans were running for a while before shutting down.

Now I haven't had any problems with overheating when idling for long periods, I was wondering if the running of the engine at high RPM's with no airflow other than my fans, should cause the overheating condition or if teh fans should have still been able to pull the temps down enough.

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post #2 of 5 (permalink) Old May 4th, 07, 03:24 PM
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Location: Leesburg, Indiana
Posts: 444
Re: Is this normal?

This is fairly normal since you mentioned it barfed all over your driveway. This is telling me you do not have an expansion tank on the cooling system.

The fact that you lost fluid does not mean it was overheating, it means it was running at a higher temp then allowable by your pressure rating on the radiator cap.

Now I may be wrong, but i seem to remeber that 1 pound of pressure increases the boiling point of your cooling system by 7 degrees. When you shut off the engine it actually created a heat soaking condition from your block. With the engine off your fans arent doing alot at first since the coolant is not moving, therefore even with the fans running your coolant temp increased for a short time increasing the pressure in the coolant system. (.060 on your block adds to this some)Thus the puddle on your driveway.

I personally see no issues to be concerned about. Just watch your temp gauge next time your out to be sure.


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post #3 of 5 (permalink) Old May 4th, 07, 03:37 PM
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Join Date: May 2001
Location: Ashby,MN, USA
Posts: 8,305
Re: Is this normal?

all that water that was being pushed into the block by the water pump suddenly went back into the radiator, which caused a pressure spike that overcame the spring on the cap.
an overflow tank will catch this stuff..

you don't plan sincerity.
you have to make it up on the spot.

wanna hear about 20 years ago when i was too smart to know any better?
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post #4 of 5 (permalink) Old May 5th, 07, 07:51 AM Thread Starter
Join Date: Feb 2001
Posts: 189
Re: Is this normal?

Thanks guys. So does this mean I need a different pressure cap for the radiator?
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post #5 of 5 (permalink) Old May 5th, 07, 09:17 AM
Join Date: Feb 2007
Posts: 70
Re: Is this normal?

Is your driveway at a steep slant? An air pocket can develope whenever you drain the entire system, or change engines. When you refill the system on a flat surface air may get trapped in the block and can't rise up and out. I have heard corvette owners in particular experience this when refilling the system especially after a rebuild. I know a guy with a 944 water-cooled Porsche this happened to.This happened to me when I changed engines on my 66 Chevelle. We all remedied the overheating with similar mmethods. By letting the engine idle, with the the car on my sloping driveway, with the front end jacked up as high as my 2-ton floor jack would go, with the radiator cap off, the blocked air came out of the block and into the radiator and out the filler hole. Have not had a overheating problem since.
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