BMW Repair: 95 M3 E36 Cooling Problem, replacement pumps, vacuum test

Question
QUESTION: Greetings,
I have a 95 M3 that is having a problem cooling.

I've done a few tests to lead to a conclusion although I don't want to run off..buy some parts...throw them on and pray for a resolution.

Symptoms...No fluid flow whatsoever.
I ran the vehicle to operating temperature and felt the inlet and outlet hose to the radiator...both were cool with no pressure...Heat on high,blower high...no heat.

I believed it was simply a stuck closed thermostat...replaced myself and did not solve the problem. (Filling and venting air)

I checked the condition of my engine oil to be sure there wasn't a "milk shake" to be found...engine oil is clean as well as there isn't any oil in the coolant.

Vacuum test revealed nothing out of ordinary... ie..indicator of a bad head gasket/warped head...loss of compression, compression tested for fun with no irregularities. No loss of engine power also.

I heard what sounded like a bad bearing or whine from under the hood some time before the overheating...I believe that it might have something to do with the water pump...

Fan clutch has resistance when turned....although i did notice that the fan showed little to no resistance once after shut down...moved fan blade with hand to check for play...moving front to back and showed it did have play.

I'm a student at UTI and I will be attending a bmw course soon...only mentioning because I want to be able to diagnose problems before working for the a manufacturer.

I would very much appreciate your aide in helping me to properly diagnose and treat my cooling issure.

Thankyou,
Dan

ANSWER: e36's had a very bad waterpump design.  If your's hasn't been replaced, (or if you don't know) it's time now.

All replacement pumps, OEM and aftermarket, take care  of the problem.

Just be glad it wasn't worse.  Waterpumps going can destroy a lot.  Fix it ASAP.



---------- FOLLOW-UP ----------

QUESTION: actually my water pump was replaced with the later model..with the metal impeller...what are symptoms of a bad water pump?

how soon do they normally go bad?

once my car gets to operating temperature the coolant literally "pumps" out of the expansion tank like a hot tube or a jacuzzi...

my car was involved in a front end accident...it is possible that it was damaged but I don't want to buy parts that I dont need...

thankyou,
dan

Answer
A bad waterpump could give you the jacuzzi.......but a head gasket could too.

Just replaced headgaskets on a '96 740iL that also had perfectly clear oil. Exhaust gas was blowing into the coolant and blowing the coolant out a hidden area of the head/block.

I'd still bet on the waterpump.  If you're concerned, Goodyear can do a combustion check on your coolant for <$50.

I have a '92 325i that the second waterpump lasted about 50K miles before going.