While checing coolant level noticed oil or exhaust gas bubbles coming to top in coolant reservoir. I just purchased the vehicle (88 300e) and will do immediate coolant change.

1. Do I have a blown headgasket?
2. Could it be dirty coolant?
3. Any tests I can do to rule out possiblities?

Thanks for any input...MRH

Your head gasket could have already been done but the tech did not clean it well. You might very well have a head gasket that is leaking oil into the coolant. If so go ahead and do the valve job at that time. If you do this you will have a great engine for many moons. Be sure to have the coolant tank and the hoses replaced when/if this is done.

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Benzmac:
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Gunter,

I had EXACTLY the same problem... air/oil in coolant. Get someone to check it is exhaust gas, and not just air. Mine was just air. We pulled the rad, and found the cause. The rad was blocked, and trhe resulting vacuum in the cooling system had sucked oil in from the oil cooler, and air from outside (expansion tank cap - change yours!). Changed the rad 1500 miles ago, and now theres no oil or air in coolant.

Cheers,

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Brian Drought
1991 300CE
http://www.users.globalnet.co.uk/~drought/
ICQ: 2180069