oil in expansion tank [Archive] - BimmerNut.com Forums

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snafud

01-27-2007, 01:30 PM

Hi! I recently bought a 1992 525i with about 170,000 miles and the m50 motor. I was checking all the fluids today and I noticed what appears to be oil in the expansion tank next to the radiator. Just to be sure, I put a long screwdriver down in there and looked carefully at the fluid. It looks like engine oil. What should I do? I fear that there is a head gasket problem, but the car runs great, doesn't ever overheat and the oil level is spot on and the oil on the dipstick looks fine. What should I do next? I do my own work and don't have a mechanic that I trust. Have done a headgasket before and hope that isn't the problem here.

632 Regal

01-27-2007, 01:44 PM

relax, it could just be residual from a past headgasket job. Dont worry about it, if something is really wrong you will know it.

Rus

01-27-2007, 02:17 PM

I'd change the coolant (flush the system) and then observe the new coolant's condition. If oil does not reappear then Jeff is probably right and it was just residual oil from a previous HG job.

winfred

01-27-2007, 02:32 PM

you can usually wick most of the oil out of the tank with strips of cloth or paper towel, clean it as best as you can and see if it comes back

Rigmaster

01-27-2007, 05:59 PM

Another thing to consider is that it could be auto trans fluid- if the car is an auto. The trans cooler is inside the end cap of the radiator, if it develops a crack it will allow trans fluid to seep into the coolant (ask me how I know....).

Bret

brick8

01-27-2007, 07:32 PM

what color is it?

winfred

01-27-2007, 07:37 PM

after it's heated in the coolant it all looks like baby ****

what color is it?

genphreak

01-27-2007, 10:26 PM

you can usually wick most of the oil out of the tank with strips of cloth or paper towel, clean it as best as you can and see if it comes backBetter than flushing- the heat cycles work to bring the oil to the float in the top of the tanks, if you flush, the oil clings to the insides so you don't get as much of it out as you mightt think.... I'd do both, check your coolant is blue btw, if it isn't its probably worth changing anyway ;) (Yellow is OK, but green is bad, jic u don't know)