1979 240D Rough idle, Oil Vapor Blowby
 

I have purched a 1979 240D, It sat for 2 Yrs. It has 183000Miles, I finally got it started but it won't idle. After getting it started the second time, I went under the hood to keep it going and while it was running it would at times run purfect wide open or on the top 1/4 of the acceleration. But when I let it off it would quit. while it was running at 1/2 open I removed the oil filler cap And pressure went everywhere, yuo ought to have seen my face,ha ha. I just thought that the PCV vent system may be plugged and will Check this now as I didn't think about this until now. I would appreciate any help as the car is in excellent shape at around 95% condition. Thanks

It sounds like some of the cylinders do not have enough compression to fire at idle. Do a wet and dry compression test. Some of the rings might be stuck from sitting so long. Put some Mobil I in it and run it hot and hard. If it doesn't clear up after a few thousand miles, you might need a ring job.

P E H

Jerry:

For sure you have excessive blowby and low compression, but it does start and run, so here goes:

Adjust the valves a bit looser than spec -- this will allow for them to close up if they are dirty and wear in fast. They are probably too tight, sounds like the car wasn't maintained very well to have compression problems at 180,000 miles. Tight valves will give you serious starting and running problems.

Make sure you have good fuel lines -- if the suction side is bad, you will suck air in instead of fuel, and will have running problems, along with starting problems.

Replace both fuel filters -- the little in-line clear plastic one and the large spin-on main filter. I'd run the car a while and get the engine warm first, and fill the new main filter with RedLine or other diesel fuel treatment to reduce the time it takes to re-prime the system.

Check that the hand pump is working properly -- if the seal in the pump is bad, air will get sucked in rather than fuel, and you will have running problems. You also won't be able to prime the fuel system. If the pump is at all doubtfull, replace it -- the newer type is much nicer (you don't have to unscrew it, it's spring loaded).

Pump the hand pump until you hear fuel hissing past the return spring in the fuel filter. It will take forever, even if you fill the fuel filter. Won't run until the injection pump is full.

Most likely you have a fuel line leak -- this is a classic problem on older, ignored MB diesels. You may need to pry the compression fitting off the suction line to replace the rubber hose with standard fuel line and a clamp.

Good luck!

Peter

I've heard some people say to put ATF (not too much) in the cylinders, by taking out the injector, and letting it sit for a few days to free up the rings on an engine that has sat that long. Just a thought.

If it runs good wire open, that is a sure sign that the fuel fliters and fuel lines are OK because that is when the most fuel must be delivered. Check the valve adjustment first because that costs practically nothing: 0.1 mm (.004") on intakes and 0.35mm (.014") on exhaust vales. ALso , there is no way the fuel system can cause the blow-by you described.

P E H