Quote:
Originally Posted by herc795
My 1990 heats up in traffic. The primary fan was working intermittently. I have changed both fan motors and relays. the secondary is working only when ac is on. When I get to driving speeds the temp returns to normal. I think I need to change the Coolant Temp Sensor. Does this sound correct? Also will I need to pull the plenum to do that? Any help would be great. Thanks
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I assume you have a stock thermostat - 180 degree stat.
Based on my experience with both 91 and 94, on a hot day coolant temp will go up in stop and go traffic. With 90 you can only guesstimate the actual temp since digital gauge is not in the instrumentation. My 94 would go up to 230 or more.
Going to Marc Heibeck chip, which allows early activation of secondary fan (I think at 203?), reduced coolant temp in stop and go traffic by 4-5 degrees if I remember correct.
Then I drilled one 1/8" hole on the thermostat flange and this brought the temp down by about 10 degrees. Now the car runs around 187-192 at highway speed and maintains 208 to 215 in stop and go traffic.