Mechanics

OVER HEATING AT HIGHWAY SPEEDS QUICKL

1995 Pontiac Grand Am

Engine Cooling problem
1995 Pontiac Grand Am 4 cyl Front Wheel Drive Automatic 130000 miles

My 1995 pontiac grandam quad 4 2.3l is overheating, no signs of a blown gasket or cracked head (no mixing of oil and coolant, no steam out the tail pipe.) I rebuilt the engine two years ago replacing the tstat, water pump, and hoses. Hoping to get lucky I just replaced the tstat, and had a pressure test, but nothing. The old tstat was working fine put it in boiling water and it opened. My next guess is a severely clogged radiator, but I can't see inside since there is only the cap on the reservoir can this be tested.
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Atbrobst
September 3, 2010.




You are probably on the right track with a clogged radiator. You can't see inside. You just have to judge by the symptoms. Don't be so quick to dismiss the head gasket either. You don't have to see any of those symptoms to have a bad gasket but I would go with the radiator first unless you are aware of an unexplained coolant loss.
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Wrenchtech
Sep 4, 2010.
So how can I fix it I can't drive 3 miles without it getting near the red? Should I buy flushing fluid, If so which one works the best with aluminum radiators?

Tiny
Atbrobst
Sep 4, 2010.
Nothing is going to flush the hardened crud in the radiator. Your only option is to replace the radiator and see what happens. If you still have a problem, the it gets more serious.

Wrenchtech
Sep 4, 2010.
Would a block test rule out a blown gasket? I don't feel like sinking more money into this car if it is the head or the gasket cause it will be very expensive to replace.

Tiny
Atbrobst
Sep 4, 2010.
The best way to check for that is with an exhaust analyzer. It sniffs the coolant in the radiator with the engine running for any hydrocarbons.

Wrenchtech
Sep 4, 2010.
Thanks for your help it is much appreciated I wish you lived near me then I would take my car to you. Also I read that my car gauge is not setup to run through the one coolant sensor by the water pump, and read stories about how there temp gauge was off 40+ deg F, that may explain why my fan wasnt turning on. How can I get the reading from the car computer(odb1.5)

Tiny
Atbrobst
Sep 4, 2010.
You'll need a scan tool to read the CTS data.

Wrenchtech
Sep 4, 2010.
Thanks. I was messing around with it today. I put my hand on the radiator hose and it didn't get hot until approx 220, then the fan started in the 280 area, also the dummy radiator gauge didnt turn on, and it does light up with all of the other lights during prestarting.

Tiny
Atbrobst
Sep 4, 2010.

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