This is a write-up on replacing the front crankshaft oil seal on an OM617 5 cylinder turbo diesel engine in a 1980 W116 300SD with over 315,000 miles. The procedure should be nearly the same for the W123 and W126 chassis with this engine. Many of the principles can be applied to nearly any of the older Mercedes models.

I cannot stand oil leaks! My front crank seal leak has been gradually getting worse, now leaving a spot of oil in the garage.


Since I have free time and the parts are cheap, I decided to try replacing it myself. First, the alternator bolts are loosened so the belts can be removed (17mm for mounting bolts, 13mm for tension nut).


Then remove the 10mm fan bolts and remove the fan and pulley. There is a high risk of rounding them. It is best to use a box wrench with the outer edge ground down so it will slip over them. I did not have one and yes, I rounded them. One was so bad I had to use clamping pliers to remove it.


The 8mm bolts on top of the fan shroud come out next.


Then the fan shroud comes out. Yes, it will come out, but you have to turn it on its side as pictured.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles