I just bought my first Mercedes, an 86 300sdl about three weeks ago. It is an amazing ride. It has 168,000 miles on it and has been meticulously serviced. Sunday, we drove into the driveway and it shuttered and white smoke came out of the exhaust. I suspected a blown heat gasket, but was really shocked as there was absolutely NO warning that there was anything wrong with the car...it has started and run like a dream. One of the glow plugs was wet so I continue to assume a blown head gasket or cracked head...but still cannot believe this would happen to a car with the service records this one has. Looking for a 300sdl shop repair manual without any success. Could there be something else going on? Looking for advice/ suggestions/ help finding a manual...are the ones on ebay in depth enough for DIY jobs? Thanks.

1. Squeeze coolant return hose after engine is off overnight. Pressure in hose is a possible indicator of HG /head issue
2. Check coolant for traces of oil-and vice versa
3. Do a leakdown test on coolant system to test for possible cracked head.

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87 300D 265Kmi
Factory rebuilt crate 603.96x engine at 200K

Along with the other recommendations made , I would suggest, that with the engine cold, start it up, and immediately squeeze the radiator hose to see if you have instant pressure. If you do, it might be an indication of a blown head gasket. Good luck

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96 E300d