Temperature gauge in my 1988 Toyota Supra fluctuates pretty erratically. I replaced the thermostat (boiled it and it opens and closes) and the coolant temperature sensor. I replaced the radiator about a year ago. I drained the old fluid, installed the new thermostat and filled it up with new fluid.
I will drive around for awhile and the temperature gauge will sit below halfway and after awhile it will move upward toward H in a matter of seconds. Hitting around H, it will will drop back down about the middle of the gauge and then move back up toward H in a matter of a few seconds. Sometimes I can tap on the gauge cluster covering it and will bring it back down on certain occasions. The reservoir tends to overfill after I drive around for a bit and then it spills out onto the road.
I opened the hood of the car after it has neared H and even on H and it seems normal just as if its been running around the mid-line of the gauge.
I was just wondering if it could be a bad temperature sender, bad temperature gauge in my car, or a bad radiator cap. I checked my oil and did not see any radiator fluid present on the dip stick nor did I see any oil in my radiator fluid.
There are actually about 155,000 miles not 15,500.
April, 22, 2011 AT 7:37 AM
Cap sounds like the easiest thing to replace as it is overflowing the bottle. Normally it would mean excess pressure in radiator caused by air from headgasket leak. This also the cause of most gauge fluctuations. Air in system.