1990 Mercedes-Benz 350SDL Q&A
1990 Mercedes-Benz 350SDL Question: injection pump
top of the injection pump where the lines go in leaks fuel.i would like to no if theres o rings.and if i can change them my self. - Visitor
I have the same problem, no luck finding a solution - thurb
Well it looks like this post is pretty old, but it seemed like a post was needed on this because it was unanswered. Firstly if you mean the portion on top of the injection pump that is below the injection pump lines, manufacturers do make seals for that, just be careful not to remove the plungers otherwise you will need your injection pump repaired; that'll set you back some pretty good coin. If your leak is coming from injection pump lines (the portions with bite type fittings), no o-rings exist for bite type fittings because the seal is formed between the ferrule (that's the little cone shaped thing that goes around the line near where the nut is) and the interior housing of the injector and fuel injection pump. So to make it stop leaking tighten it; if you think tightening it will break it then take the line off and look very closely on the mating surfaces between the ferrule and the interior wall to make sure that no major deficiencies exist, if they do the part will have to be replaced, however, if you are handy with a tubing bender and fittings (they have to be the right size though, that's a gotcha') you can make the part, but it's not worth your time to do it that way unless no injection pump lines are available and a defect exists between mating surfaces, or of corse there is a break in the line close to one of the fittings. If you can't see anything wrong with the mating surfaces or would just like to try cleaning them grab a lint free rag and go to town on the fittings using diesel to clean them, then after you're done cleaning it, reinspect it to make sure no new gunk got on the mating surfaces, then reinstall the lines; it's best to take off one at a time so you know were it goes on the car. To tighten the lines turn the nut on the line until it begins to bite as evidenced by a sharp rise in torque required to continue to turn the nut (a pretty noticeable one mind you, don't let surface irregularities trick you), then after you get that sharp rise in torque, turn the nut an additional 1/4 to 1/2 turns to properly set it. - Peter Plowman
The top of the injector pump frequently starts to leak. The culprit is the low sulfur diesel. The copper seals fail. A special tool as well as a torque wrench is needed to remove and reinstall the holders. It is important to change only one seal at a time so that you do not mix up the springs or the plungers as they are calibrated. I did this on my pump and stopped the leaks at this point. - troubled_one
Fuel leaks can develop around the high pressure fuel injection pump.