What does oil in fuel filters mean? 1986 Mechanical S1954

No but it can cause a leak. Just fix it. If it is an older truck like you say, it has probably sat for an extended period of time and that is when algae tends to appear.

 

Algae loves the water if it's getting into your tank. The last bout of algae I had though, seemed to be caused from using biodiesel. If I recall I had spent a lot of time in IA or MN(?), one of those states mandates a certain amount of biodiesel be used in fuel sold in their states.

 

The algae will start breaking up and clog your filters several times before its all cleared up. You won't have a choice but to change them. Good luck. Keep a gallon jug with diesel to fill filters.

 

When was the last time the tanks were flushed and fresh fuel run through this engine? You will have a mechanic fuel injection pump on that. I do not believe those can get engine oil inside the pump. I agree the discolouration is more likely from algae. The blue smoke is probably from burning oil which is not shocking with an engine of that age. There is probably a fair amount of blow by and oil tracking up past the rings. The injectors are old school pencil type I believe that only fired from fuel pressure, no heui systems in those. If you have a turbo charged engine, check the turbo for passing oil into the intake, this will cause oil burning too.

 

Airman, is it really blue or just 'light' black? A mechanical motor is gonna smoke some. You ought to see mine in the morning. #### near have to walk out of the shop when it's warming up.

 

Great, like I said, just keep extra filters for a while and don't sweat it. Just run the old girl.
More than anything the truck probably just needs to be ran.