Mechanics

COMMON PROBLEMS IN COOLING SYSTEM?

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?
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Mjohnson1
July 4, 2012.



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

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.

KHLow2008
Jul 4, 2012.
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.

Tiny
Mjohnson1
Jul 10, 2012.
Is the coolant still overflowing from the reserve tank?
Does the temperature increase with speed?
When does the temperature increase?

KHLow2008
Jul 10, 2012.
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.

Tiny
Mjohnson1
Jul 10, 2012.
Is the 3rd plug the cylinder that has a lower compression?

A bad head gasket can cause the difficultng starting when cold and the overheating as pressure is too high in cooling system and would force coolant out of the overflow tube.

Try running with A/C n to see if there are any difference.

KHLow2008
Jul 10, 2012.