In Reply to: 88 M3 Running Hot posted by Chris Schrimsher on May 03, 2000 at 12:17:13:
: Here is what I have observed:
: -Coolant in overflow tank is at mid point seam, or 1/2 full. I believe this is right where it should be.
: -Coolant leaked a little three weeks ago but not any more.
: -Driving with heater running keeps temp gauge in the normal, mid-point range.
: -Turning on heater will immediately cause temp gauge to drop from about 3/4 down to the mid point.
: I've read some of the threads on similar problems and yesterday evening I ran the car in the garage so that it would heat up. I was able to get the temp gauge just past 3/4's before I shut it down. I had to rev it a bit to get it this high otherwise it would have leveled off somewhere between 1/2 way and 3/4.
: Here is what I've checked out:
: -The auxiliary fan in front of the radiator NEVER ran but the one behind the radiator did.
: -I carefully removed the pressure cap after shutting down and used a cooking thermometer to measure the temp. It was 170 F whereas the temp gauge below the tach read about 150 F.
: -The cap hissed a bit as I removed it so I assume it's holding pressure ok.
: -Both upper and lower hoses attached to the radiator were hot so I assume the thermostat is functioning and the radiator is not clogged.
: -I assume the water pump is fine since it no longer leaks coolant.
: -I checked ALL fuses and they looked ok.
: -I manually rotated the auxiliary fan blades and they turned so it is not seized.
: The Plan:
: -Remove the auxiliary fan and have it tested. I assume this can be done, right? Replace if necessary.
: -Flush radiator while it is out.
: -Remove and test thermostat while radiator is out. Replace if necessary.
: -Take a closer look at wires running from thermostat to make sure they are not brittle and broken.
: -Flush entire cooling system.
: -I'm troubled with the disparity between the temp of the coolant I measured with the cooking thermometer and what the temp gauge below the tach reads.
: -Is it just the coolant is low?
: -Will I be able to tell if the auxiliary fan is bad?
: -Will I be able to tell if the radiator is clogged?
: Am I missing anything?
: Chris Schrimsher
: [email protected]
My aux fan stopped and I had it fixed a couple of weeks ago. The resistor had blown and some wires had come loose at the thermal switch. When the wires at the switch were fixed and the resistor replaced the fan worked fine. Make sure that the switch is ok too. I also changed my coolant tank resevoir cap too. I did not have major overheating problems but it did run just a little over half and a little hotter when i started it. Check the relays too, that could be a problem.