I've been chasing an overheating problem forever now. The car is actually not overheating but continually runs hotter than its supposed to. I have a '98 Mistu GST Turbo with 89k. I've replaced pretty much everything in the coolant system at least once. New radiator, water pump(w/20k on it now) 2 oem thermostats and oem rad cap, and both temp sensors(gauge and ecu) and confirmed fan comes on once operating temp has been reached. The needle normally runs right in the middle of gauge and now runs 2/3 to 3/4 up gauge. I pulled the first oem thermostat and drilled 2 small holes, which helped and it only ran slightly hotter than normal. Then I purchased a new 2nd oem thermostat and it runs hot again about 3/4 way up gauge. Also, once it does start running hot I can push in clutch and coast and temp immediately drops to middle of gauge and then if I put back in gear it jumps right back to where it was. If I leave it out of gear and coast, it will drop down but slowing climb back up to 3/4 of gauge.
Forgot to mention. First oem thermostat that I mentioned was new as well and had same effect and 2nd oem thermostat, before removing and drilling the 2 small holes. Those this has worked the best I pulled it so I can try to fix the correct way instead of the band aid fix. I also purchased a coolant pressure tester kit and found the system does hold pressure, although I have not tried this once the car has reached operating temp, not sure if that will make any difference.
I've been meticulous about getting all air out of the system. With the oem (non drilled) thermostat it will overheat during any condition once driven. If I start it and just let sit it will reach operating temp and maintain. Once driven, street or highway it goes to 3/4 on gauge. With the drilled thermostat it runs fine on the street(wouldn't even know there was a problem) and on highway it usually ready slightly higher on gauge about, 2/3 sweep.
Well the wate rpump is run off the timing belt, both of which were replaced about 20k ago. I have a program on my laptop and cable that I can hook up to the obd2 port and will read was temp the ecu can see, because it uses a diff sensor than the one for the gauge or rule that out. Otherwise, if it possibly a head gasket, can/should I do the pressure test after its heated up to possibly reveal a loss of pressure?
have the same problem?
Monday, February 21st, 2011 AT 1:49 PM