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Junior Member
 
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Last Login: 9/3/2008 2:58:35 PM
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| I was at an autocroos Sunday with my new used M3. The engine ran very hot. The temp guage passed the third white line indicator although not into the red and it did not boilover. I checked the coolant lvl and it was fine. Are there any areas that commonly cause overheating in the E36 M3? The engine has 70K and has seen light duty. I was thinking of changing the thermostat incase it was sticking. Obviously the fluid change as well at that time. I hope the radiator is not shot. BTW, I had to put the heater on full blast while cruising on the highway. It definitely kept it from overheating.
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| The cooling system on E36's is probably the car's weakest point. By 80k miles, it's time to do a complete refresh (if you want a 100% reliable solution that you won't have touch for the next 80k miles). Anything else is just a patch, and some other part of the system may go any day. Problems: Plastic radiator and overflow bottle - The radiator usually fails where the upper radiator hose connects to the radiator. You can replace the radiator with another stock radiator for ~ $150, or you can get an aluminium radiator for $400-$500. Water Pump. There are at least 3 'stock' water pumps. Some have a metal Impeller, some plastic, and some have a composite. They all fail, the question is just when. I replaced mine with a Stewart aftermarket pump. They flow more and have a lifetime guarantee, but cost $200. If you're going to do all that, you should probably replace the hoses and belts (since they have to come off anyway). And check the fan - the fan clutch has been known to fail. With the engine OFF, you can grab the fan and see how easily you can spin it. You should not be able to spin it, you should be able to move it though. If you can spin it, the fan clutch is gone. If you do drain the fluid, replace it with BMW's Blue Antifreeze fluid. You drive a BMW after all, don't put $5 a gallon PEP Boys stuff in there..... And a bottle of Water Wetter can help also. You do have a problem because the Temp on my M3 never moves beyond 12:00, no matter how warm it is outside. Also, if you keep your radiator, it could be blocked. Leaves and other crap can clog up the fins and block airflow. Good Luck. 
Jim Dresser
'98 M3
'01 Subaru Outback
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| tx a bunch, very helful. I know for a fact the fan clutch is gone. The fan spins freely with a finger. Would that be enough to cause the entire problem? There are no leaks at the top of the radiator or plastic overflow bottle. Do I need to have it pressure tested? Where is the best place to buy parts like the water pump?
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Junior Member
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| "Is the bad fan clutch your entire problem?" - I sort of doubt it, but here's how to test. Just go for a drive with the heater off. When you're driving over 20mph, there is more air moving through the radiator than the radiator fan could ever move. (The radiator fan always turns, but it only moves significant air when you're stopped) So, if you drive and it still overheats, there is something wrong besides the fan clutch. I'd vote for either water pump or clogged radiator fins (thermostat is 3rd choice). Pop the clips that hold the radiator in place, and look between the radiator and the air conditioning evaporator coil (the air conditiong radiator). I bet there are all sorts of leaves and dead bugs in there, blocking air flow. You can get these parts anywhere, your dealer, Turner, UUC... But I got mine from Bimmerworld: http://store.bimmerworld.com/shared/StoreFront/default.asp?CS=bimmerworl&StoreType=BtoC&Count1=56484401&Count2=973624825&CategoryID=7&Target=products.asp Jim
Jim Dresser
'98 M3
'01 Subaru Outback
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P.S. If you change the thermostat, you need to remove the thermostat housing. This is plastic also, and has been known to split. Replace it with an aluminium housing.... This is one of those 'while you're in there, you might as well....' things.
Jim Dresser
'98 M3
'01 Subaru Outback
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Another test you can do is open the expansion tank cap while the car is running. Look in there and you should see a pretty steady stream of coolant being sprayed in there. That's a good indication that your water pump is working. If you don't see a good stream then chances are the water pump is shot. Get it out of there!
Jim is right, all the "stock" water pumps will fail. If you're going to keep the car, spend the money and get the Stewart pump. Jim is also right that you should just replace all the suspect parts, thermostat, radiator, water pump, hoses, expansion tank.
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| You are at the time and mileage to do a radiator, water pump, thermostat housing, coolant, etc. If the car got hot enough to do any damage to the head, watch for coolant loss but nothing leaking on the ground. If any head damage might have occurred, you will see white jelly-like stuff under the oil cap or strange colored oil. This will clog things up eventually and can be hard diagnose as a cracked head since is can seal off until the car is at running temperature. These cars are not the cheapest to keep, but make owning any passionate car near as much fun look extremely costly.
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Last Login: 9/3/2008 2:58:35 PM
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| I'm going to order the water pump. The car ran hot on the highway which suggests a problem with the pump or radiator. It is a recent development so I'm leaning toward the pump not radiator.
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