BenzWorld Junior Member
Date registered: Jun 2016
Vehicle: 1968 250 SE automatic
Location: Queensland Australia
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Problems with petrol injector pump on 1968 250 SE Mercedes Benz W108 series automatic
My next door neighbour has completed a total restoration of a 1968 250 SE, W108 series Mercedes Benz automatic sedan including a total rebuild of the 6 cylinder petrol engine. I have been helping to get the engine running but there seem to be serious trouble with the petrol injection pump system. Although the engine will start it runs very roughly and pours lots of black smoke from the exhaust. After having the engine running, the spark plugs become sooty.
We have checked and double checked all the linkage adjustments and fuel supply hoses in accordance with the workshop manuals and installed new injectors but can't overcome the rough running or get the engine to idle.
We suspect the injector pump is injecting far too much fuel to the injectors as there are now signs of fuel in the sump oil but we can't find any sign of leakage from the pump to the main oil system.
Unfortunately, we haven't been able to find anybody out here in country Australia with experience or testing facilities for the Bosh injector pump (80327416 PESAKL 708120R21 ) and are working in the dark. I have read several posts by "bostosh" on the injector pump on "124wagon_boy's" 1966 250 SE coupe and have done most of the tests he suggested but have not solved the problem.
What could cause fuel in the oil? Could it come from leakage within the injector pump or could it could it come from excess fuel through the injectors
I would welcome any suggestions or assistance anyone can offer to help get this beautifully restored vehicle back on the road.