Am I going down the right path? - PeachParts Mercedes-Benz Forum

strelnik · #1 05-04-2014, 08:52 PM

Profile: 1983 240D auto with 233K miles on the engine and a rebuilt trans about 50,000 ago.

Two months ago I quit driving the 240D – driving two diesel trucks instead. A month later, I started the 240D and it blew a lot of black smoke and seemed to be operating very roughly.

I adjusted the valve lash and it seemed to smoothen things out somewhat after I let it warm up. I was suspicious about the engine mounts because the motor vibrated more when cold than I thought it should.

Replaced the old ones with Lemförders and replaced the engine shock damper on the driver side of the engine.

Replaced both fuel filters as well.

Had no trouble starting it but am still getting more vibration than I want plus a lot of black smoke.

Am thinking two things: stuck injector or stuck rings.

I change oil regularly so the stuck rings seems unlikely.

I have ordered rebuilt 240D injectors and am awaiting them. Bought them to have them available if needed in future.

I believe my next step would be to check compression. This would definitely tell me if I had an internal engine or valve train problem, without major work.

I can go through the glow plug holes and check the basic compression. If more or less even, my money would be on injectors, so I’d probably change all four, get new washers/seals, then get the others rebuilt for the future.

Any other suggestions?

What do you think of the plan?

I know the 240D / OM616.912 is a good engine, but not as smooth as the newer ones. Still it should be smoother than it is.

cooljjay · #2 05-05-2014, 03:08 AM

Do a diesel purge and drive it like you stole it.....black smoke is usually fuel....so you have a fuel issue more then likely....replace injectors, use member greazzer, maybe check injection pump timing, look at adjusting the fuel pressure relief valve..

t walgamuth · #3 05-05-2014, 06:30 AM

Quote:

Originally Posted by strelnik

Profile: 1983 240D auto with 233K miles on the engine and a rebuilt trans about 50,000 ago.

Two months ago I quit driving the 240D – driving two diesel trucks instead. A month later, I started the 240D and it blew a lot of black smoke and seemed to be operating very roughly.

I adjusted the valve lash and it seemed to smoothen things out somewhat after I let it warm up. I was suspicious about the engine mounts because the motor vibrated more when cold than I thought it should.

Replaced the old ones with Lemförders and replaced the engine shock damper on the driver side of the engine.

Replaced both fuel filters as well.

Had no trouble starting it but am still getting more vibration than I want plus a lot of black smoke.

Am thinking two things: stuck injector or stuck rings.

I change oil regularly so the stuck rings seems unlikely.

I have ordered rebuilt 240D injectors and am awaiting them. Bought them to have them available if needed in future.

I believe my next step would be to check compression. This would definitely tell me if I had an internal engine or valve train problem, without major work.

I can go through the glow plug holes and check the basic compression. If more or less even, my money would be on injectors, so I’d probably change all four, get new washers/seals, then get the others rebuilt for the future.

Any other suggestions?

What do you think of the plan?

I know the 240D / OM616.912 is a good engine, but not as smooth as the newer ones. Still it should be smoother than it is.

Sounds like you are on the right track. Could also be stuck valve.

strelnik · #4 05-05-2014, 12:06 PM

Quote:

Originally Posted by cooljjay

Do a diesel purge and drive it like you stole it.....black smoke is usually fuel....so you have a fuel issue more then likely....replace injectors, use member greazzer, maybe check injection pump timing, look at adjusting the fuel pressure relief valve..

I have injectors coming from greazzer, just looking at other stuff too.
Thanks!

strelnik · #5 05-12-2014, 08:22 AM

Quote:

Originally Posted by strelnik

I have injectors coming from greazzer, just looking at other stuff too.
Thanks!

I did the diesel purge, following everything to the letter.

When the car was warmed up, and idling at about 900 rpm, it was quiet and no smoke.

I changed the fuel filters following the purge.
Black smoke and a tapping noise coming from the top of the engine.

I am figuring that there's a valve that needs more adjustment, even though the valves were adjusted a month ago and the car not driven.

I am going back into the valve train to check and possibly readjust any valve which is not within +.001" of spec.

Results in a few days, suggestions welcome.

Maxbumpo · #6 05-12-2014, 08:41 AM

Quote:

Originally Posted by strelnik

I did the diesel purge, following everything to the letter.

When the car was warmed up, and idling at about 900 rpm, it was quiet and no smoke.

I changed the fuel filters following the purge.
Black smoke and a tapping noise coming from the top of the engine.

Really sounds like a fuel issue. Valves don't get better and then get worse.

I suspect when you change the fuel filters, you introduced some contaminant that is now plugging an injector.

strelnik · #7 05-12-2014, 09:01 AM

Quote:

Originally Posted by Maxbumpo

Really sounds like a fuel issue. Valves don't get better and then get worse.

I suspect when you change the fuel filters, you introduced some contaminant that is now plugging an injector.

So whaddaya think? More diesel purge? and what about the tapping?

Maxbumpo · #8 05-12-2014, 09:05 AM

Diesel purge worked once, might clear it again.

Tapping could be due to a fuel injector plugged open and dumping fuel, which then causes noise with the piston tries to compress liquid fuel instead of atomized fuel.

funola · #9 05-12-2014, 09:34 AM

Quote:

Originally Posted by strelnik

So whaddaya think? More diesel purge? and what about the tapping?

I wouldn't bother with another diesel purge. I did it once and it did not do anything good or bad. Waste of money and time IMO. I soaked an injector tip with some carbon in the stuff afterwards and it did not seem to have any more solvent action than straight diesel.

Car sitting for a few months should be no problem if the fuel system is tight and not letting moisture in.

Have you checked the air filter? Give it an Italian tuneup and see if the black smoke clears.

funola · #10 05-12-2014, 09:40 AM

Quote:

Originally Posted by strelnik

..........

I changed the fuel filters following the purge.
Black smoke and a tapping noise coming from the top of the engine.

.............

Where is the black smoke coming from? Leaky exhaust? Plugged exhaust? Did you try a stethoscope to isolate the tapping noise?

Do you have a clear return to tank line i.e. a clear cigar hose? If you have bubbles there. fix it.

Stretch · #11 05-12-2014, 01:10 PM

If the car was running with out this trouble three months ago I would put fuel as my first suspect - I don't know about the fuel where you live but here in Europe they mix in quite a bit of bio products to petrol and diesel. If you don't use the fuel it separates and you get trouble. There are lots of really fed up fair weather motorcyclists who spend a lot of time cleaning out carbs!

strelnik · #12 05-12-2014, 01:11 PM

Quote:

Originally Posted by funola

Where is the black smoke coming from? Leaky exhaust? Plugged exhaust? Did you try a stethoscope to isolate the tapping noise?

Do you have a clear return to tank line i.e. a clear cigar hose? If you have bubbles there. fix it.

I have a wooden dowel 36" long that I put against the bone under the ear to head vibes.

Will also try the air cleaner and see how bad the air filter is

Could this be caused by an EGR valve? I don't think the 83 cars had them. Haven't checked.

Maxbumpo · #13 05-12-2014, 02:16 PM

Quote:

Originally Posted by strelnik

Could this be caused by an EGR valve? I don't think the 83 cars had them. Haven't checked.

EGR, if failed in open state, will cause smoking from unburned fuel, but will not cause noises (tapping).

funola · #14 05-12-2014, 03:26 PM

My 83 240D had a egr computer which I modified to drive a tach. Did a DIY on it.

Junkman · #15 05-12-2014, 06:41 PM

If it ran before., try some Startron and take it out on the road for an Italian tune up.

See if "Marshall Booth Italian tune up" brings up anything.