Operating temp (Page 2/3) olejoedad AUG 04, 12:11 AM The HOT bulb has power with KEY ON and the sensor circuit provides a ground, illuminating the bulb. Rhodesia1977 AUG 04, 09:47 AM Thanks for the advice. Rhodesia1977 AUG 04, 09:49 AM Makes sense. Thanks! Rhodesia1977 AUG 04, 11:45 AM Ok so I went on a test drive. About 6 miles 35mph average speed. Ambient air temp is 82 degrees. My temp gauge read 185. I took readings from a laser thermometer. The brass base of the temp gauge sender sensor said 235. T stat housing said 189 and upper radiator hose said 185. Engine block from different spots said 185-195. No engine problems or burning smells. Checked gauge wires and all ok. Not sure what the heck is happening. The temp gauge sensor temperature temp really worries me. Any suggestions?? greenturnedblue AUG 04, 03:35 PM At 235*, the fan switch should kick in, activating the fan to prevent coolant from boiling over. If the coolant temp sensor probes at 235*, but the fan does not come on, and literally everything else is 185-190*, I would suggest your sensor is malfunctioning, but you say it is new. Did the temp light come on (dim?) at any point? Rhodesia1977 AUG 04, 03:43 PM My over temp light did not come on. It does come on for about 2 seconds when the car is started (test light?) and then goes out. I took temps at all areas on engine. Everything, radiator, motor block, t-stat housing, upper and lower radiator hoses, was from 175-195ish. The base of the temp coolant sensor to gauge read at 235. The fan also has a manual switch and it was running full time (I manually engaged it) for fear of overheating. There are no other tell tale signs of overheating. I tried to get the t stat off but the top will not budge. Anyway I am at a loss. We have a car show Saturday to go to but maybe I shouldn't. Not sure what else to do to see if it is actually overheating or not. Thanks for the tips, I really appreciate it! Rhodesia1977 AUG 04, 03:47 PM One more question. Let's assume that I have the mechanical knowledge of a hamster. What tell tale physical signs would one see or hear on the 2.8 if it was in fact over heating? We recently took it to a car show last week (that's when I noticed the dim high temp light) and it was a 70 mile drive both ways. No overheating signs and car drove fine. Air temp was about 85 degrees. Patrick AUG 04, 04:11 PM quote Originally posted by Rhodesia1977: What tell tale physical signs would one see or hear on the 2.8 if it was in fact over heating? Assuming there is coolant in the system... coolant puking out the reservoir. Rhodesia1977 AUG 04, 04:23 PM quote Originally posted by Patrick: Assuming there is coolant in the system... coolant puking out the reservoir. After a long drive the coolant reservoir may get a little higher maybe 2 cups after the car cools but no it doesn't overflow or gush out. Hey I really appreciate your info. Unfortunately, I'm not much of a mechanic but the Fiero has been teaching me! greenturnedblue AUG 04, 04:33 PM Not sure if you are aware but all Fieros came with an error in the wiring from the factory. When the key is turned to 'on' all the problem lights on the dashboard are meant to come on to test the bulbs work. But, the pulse that was meant to flash the coolant overheat light was mistakenly sent to the gauge, causing the needle to pin right when the key is turned to on. and since it isnt sent to the overheat light, the light would not illuminate on key on. Since your coolant temp light does come on when the key is in the on position, either someone has corrected the factory wiring mistake, which involves swapping two wires behind the dash and at the sensor, the sender is bad, the sender pigtail wires are reversed, or the wire shorts somewhere along the line. If nobody has fixed that factory error, I would suspect it is a wiring problem because of the light coming on dim. Whatever the root cause is, could be causing both the light coming on dim as well as the light coming illuminating with key on AFAIK, the base of the thermostat housing is the most accurate place to get a temp reading from an infrared thermometer. Since that says 190-195*, I think you are fine, even if the sensor itself reads hotter (aside from the wiring issue) If the car does overheat, you will see a **** ton of steam coming out the thermostat cap. This is your coolant boiling over around 260*. You cant miss it, keep your eyes in the rear view mirror to see any steam coming out the decklid vents. Since your gauge also appears to be operating normally, if it pegs right in the red zone stop driving immediately. But at that point, it will not be long before permanent damage occurs: head gasket failure, warped heads, catastrophic engine damage like a cracked block, seized pistons etc et etc.