Common problems in cooling system?

MJOHNSON1

MEMBER
1999 PONTIAC GRAND AM
98,000 MILES

The engine is overheating. At apporximately 216 degrees the coolant starts coming out of the overflow before it ever hits the red. Have replaced fan relay, temp sensor, thermostat, waterpump. I have flushed the radiator and that is flowing fine. There is no water in the oil and the engine purrs like a kitten. I have read thatchanging the reserve tank cures the problem. In your guesstimation will it?

6 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

I would have a leak down test done to rule out a head gasket. Start from there. Otherwise, my guess is a clogged radiator.

Roy

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Wednesday, July 4th, 2012 AT 5:01 PM

KHLOW2008

MECHANIC
41,815 POSTS

Radiator cap is often overlooked when overheating occurs. Changing the reserve tank or cap might cure the problem if they are not maintaining pressure and allowing coolant to overflow.

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Wednesday, July 4th, 2012 AT 5:04 PM

MJOHNSON1

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3 POSTS

Thanks for the help guys. We replaced the reserve and it has helped some but still going on the high side, bled everything too to get the air out. We just ran a compression test and they are all at 185 except one at 170. Should we now be thinking intake manifold gaskets? Any suggestions are apreciated.

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Tuesday, July 10th, 2012 AT 12:52 AM

KHLOW2008

MECHANIC
41,815 POSTS

Is the coolant still overflowing from the reserve tank?
Does the temperature increase with speed?
When does the temperature increase?

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Tuesday, July 10th, 2012 AT 1:35 PM

MJOHNSON1

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3 POSTS

Yes the coolant has overflowed minimally from the reserve tank, not nearly like it was before changing everything out. Yesterday, even after driving it and it looking low, as the car cooled it came back up to the cool full line. The temp steadily climbs to 200 then seems to fluctuate between 200 and 210, it's seems to get higher while in drive and at a stop light. It has been retreating and coming back down, on Saturday with the air running (as it was over 100 degrees outside)it overheated to 260, I pulled it over let it cool some and added antifreeze and all seemed to be well. In pulling the plugs yesterday to do the compression test we noticed that the 3rd plug looked lighter at the top then the rest. Also since Saturday, I have not run the air and have used the car minimally, which has been ok. On side note, that I don't know if related or not it has been hard to start after it sets for more than a few hours, but once it starts then it is fine.