1993 Pontiac Grand Prix LE from North America - Comments

2 issues:

Engine runs hot, but doesn't overheat.

Emission test failure 4 times in a row.

Overall, it is a reliable car. Leaked oil until I changed oil ring on the oil shaft and put silicone on the cap. This is the most common spot for leaks on 3.1s.

Who knows how to get the temperature down? Why does it run rich? Is it ECM (computer) set up?. My temperature gauge is half the way (which is good for winter), but I am not sure I will like it like that during the summer. I do not lose coolant, which is a good sign. People say that my engine runs rich. Who has the same problem and how to handdle it?

Emission failure is due to the high cylinder tempereture. Passes everything except NO.

My previous car Lumina (which is the same drivetrain as Grand Prix) never overheated. I found out later that the thermostat was stuck open. Maybe I have to put it on Grand Prix?

I recently purchased a 1993 grand prix LE. I'm having trouble with the temp. not stabilizing. It seems to drift up and down from 190 to 225 while I'm driving or stopped. I'm afraid the head gasket is blown or the head is cracked. Also, I noticed moisture coming from the exhaust. Can the engine be pressureized to checked? Thanks!

Chris.

I fixed my problem with "running hot" condition very simple. I bought 180 F thermostat and replaced mine. When I took old one out, it was written that it is a 195 F rated thermostat. Thus, it was "running hot". I bet most of 93 Grand Prixes have 195F thermos too. Now the temperature stays perfect because it opens earlier. I also replaced original 16 psi rated radiator cap with 13 psi radiator cap. Radiator cap increases the efficiency of the cooling system by reducing the boiling point by putting more pressure. I decided that I would rather radiator cap open at 13 psi and let the coolant out of the system in the overflow tank, than to have a blown head gasket and get my coolant in oil. For the car being that old it is a real possibility. I hope it will prolong my engine life.

The shop can check every cylinder for the pressure rating. If one of them is substantially low, you have a blown cylinder. Moisture coming out during the warm up cycle is normal. Check the level of your antifreeze for sometime in the morning before you drive and see if you loose some. If not, your engine shouldn't be blown.