i keep getting a false reading on the stock temp gauge of my 85 gsl. i replaced the coolant, t-stat, and temp sensor. the temp remains between the lines near the cold mark. any suggestions?

 

Maybe your fan clutch is frozen so it's not letting your engine warm up.

 

Still wouldn't matter as long as the thermostat was closing properly.

1. Thermostat is bad, and not closing at cold temps.
2. Bad installation of thermostat? Maybe not in straight or something?
3. Clean all connectors on the temp sensor, might have a bad ground.
4. When the engine is cold, remove the radiator cap and then start it up. Can you see fluid moving through the radiator? If so, then the thermostat is not closing as it should (happens sometimes).
5. Some people claim that nothing other than a dealership thermostat should be used.
6. What temp range did you get for the thermostat. Too cold?

 

i changed the t-stat correctly. made no difference. when i did this, i flushed the system. i cleaned the temp sensor and nothing. i installed a used one that tested good. coolant is still in the radiator. the t-stat is a 180.

 

Are you using Mazda thermostats? I had the same problem with the 1/2bp, with a non-oem stat. Replaced with an oem one, temps are normal now. I have an aftermarket temp gauge. 150*-non-oem, 180*-oem coolant temps. Both stats were 180*units.

 

i'm using a NAPA brand t-stat. maybe i'll try the oem thermostat. i was thinking wiring. either to the gauge or that the actual gauge is faulty.

 

Gauge may not be accurate, but many of the non-oem stats do not block off the bypass hole.

 

i think i may try the oem t-stat before i resort to much else. i noticed the napa brand thermostat didnt have an air bleed, which would need to be upright in postition. the previous owner said the gauge worked fine. i'm thinking it didnt. the thermostat i pulled out was an aftermarket and did not have the air bleed.

 

Sounds like a good plan Stan... Let us know your results.

 

When I first had an overheating problem, I changed out the thermostat to a non-oem one, and the engine would never warm up, tried another one, and same thing. Went back to an oem one, and everything worked fine.