Black Smoke, Rough Idle, Dies at Idle - Page 2 - PeachParts Mercedes-Benz Forum

Graplr · #16 06-29-2012, 09:28 PM

Quote:

Originally Posted by rscurtis

That engine has a breathing problem. It's either a bent, tight, or leaking intake valve, or possibly a flat lobe on an exhaust valve, causing the cylinder to exhaust into the intake. A cylinder that is not getting enough air will also give you your smoke.

I'm curious what led you to this diagnosis?? Not disagreeing, just trying to learn. How would I go about isolating the specific valve, etc. And then how would I go about fixing the issue?

I do have some unusual "clatter" (not normal diesel clatter) from the engine upon acceleration. I assumed it was some piston slap but it very well could be a valve. I'm not really sure how to diagnose. I guess I could post a video of that sound.

Graplr · #17 06-29-2012, 09:31 PM

Quote:

Originally Posted by Diesel911

In that thread the Little and only O-ring that is in the Lift Pump was no good and it was sucking Oil from the inside of the Fuel Injection Pump into the Fuel.

But, if you have read the other threads putting Lube Oil in you Fuel dose not make the Engine run worse. Although it could cause smoking.

I'm not sure if this is happening since the fuel was mostly clear, albeit not the exact same color as the fuel getting put in. Perhaps the Power Service treatment colored it, I don't really know. Either way I'm doing a Diesel Purge and changing filters as the clear one is dark. If the filter darkens back up quickly I'll check and replace the o-ring. I could have more than one issue but the odd thing was that it really came out of nowhere yesterday. Granted the engine had some issues to begin with but it has gotten worse all of a sudden.

Alastair · #18 06-30-2012, 06:26 AM

Definately worth checking the Injector spray-patterns or replacing them if they are high mileage parts...

Poor/no spray-pattern can make for exactly the symptoms you describe....

rscurtis · #19 06-30-2012, 10:40 AM

Quote:

Originally Posted by Graplr

I'm curious what led you to this diagnosis?? Not disagreeing, just trying to learn. How would I go about isolating the specific valve, etc. And then how would I go about fixing the issue?

I do have some unusual "clatter" (not normal diesel clatter) from the engine upon acceleration. I assumed it was some piston slap but it very well could be a valve. I'm not really sure how to diagnose. I guess I could post a video of that sound.

You can hear the "bark" in the intake when that cylinder comes up on compression. You discovered the answer in your initial post when you stated that the PO did a compression test and one cylinder was "really low". That is your problem, not air leaks or bad injectors. After verifying that all the valves have clearance, the next step IMO is to remove the head and see what's physically damaged.

kerry · #20 06-30-2012, 10:49 AM

Quote:

Originally Posted by rscurtis

You can hear the "bark" in the intake when that cylinder comes up on compression. You discovered the answer in your initial post when you stated that the PO did a compression test and one cylinder was "really low". That is your problem, not air leaks or bad injectors. After verifying that all the valves have clearance, the next step IMO is to remove the head and see what's physically damaged.

He already adjusted the valves on that cylinder. I'd say a compression test on that cylinder again might be in order.

Graplr · #21 06-30-2012, 09:52 PM

Quote:

Originally Posted by rscurtis

You can hear the "bark" in the intake when that cylinder comes up on compression. You discovered the answer in your initial post when you stated that the PO did a compression test and one cylinder was "really low". That is your problem, not air leaks or bad injectors. After verifying that all the valves have clearance, the next step IMO is to remove the head and see what's physically damaged.

Either way, I'm not going to even consider pulling the head until I park it for the winter. If it is a valve problem, I wouldn't need to pull the head, correct?

I did a diesel purge and changed the filters last night. The clear filter has completely black on the plastic even thought there was no fuel in it. I haven't been checking them daily, but when I first started driving it amount 1.5 months ago it was clear. Now it is completely clear and I can see the fuel where as before I couldn't. It did seem to help at first but I had more symptoms today of very sluggish off the line and lots of smoke. Although the engine never died with plenty off opportunity to do so.

I do agree with Kerry that I should recheck the valves and then perhaps compression check.

mach0415 · #22 06-30-2012, 10:40 PM

Quote:

Originally Posted by kerry

He already adjusted the valves on that cylinder. I'd say a compression test on that cylinder again might be in order.

Better yet, a cylinder leak down test - one of the most looked over simple tests that tells a lot, but is often skipped before sometimes removing the head in vain.

layback40 · #23 06-30-2012, 11:05 PM

Quote:

Originally Posted by mach0415

Better yet, a cylinder leak down test - one of the most looked over simple tests that tells a lot, but is often skipped before sometimes removing the head in vain.

X2
As this is a NA motor it will behave a little different to a turbo.
Leak down will show where the problem is.

Black in the primary filter could be a sign of a bug problem in the fuel.
Could have a bad delivery valve as well.

Graplr · #24 07-01-2012, 08:31 AM

Quote:

Originally Posted by layback40

Black in the primary filter could be a sign of a bug problem in the fuel.
Could have a bad delivery valve as well.

The thing that I don't get is the fuel is clear. After the filter change it is completely clear so I'm confused as to how the filter got black.

layback40 · #25 07-01-2012, 09:14 AM

Quote:

Originally Posted by Graplr

The thing that I don't get is the fuel is clear. After the filter change it is completely clear so I'm confused as to how the filter got black.

When you get bugs in the fuel, it doesnt always change the color of the fuel. You get a residue like perished tire rubber building up. It can be like a scum deposited on the surfaces that are weted by the fuel.

Graplr · #26 07-07-2012, 05:55 PM

The problem mysteriously cured itself. It was behaving like this for just over a week. It was a real struggle off the line. It would literally crawl until I got to about 15 mph from a dead stop. Tons of black smoke, even noticeable at highway speeds.

Last night on the way home at about 9pm, there were no more symptoms. Smoke was gone, back to normal power off the line, idle was much better.

There was nothing specific that I did yesterday to fix the issue. I did put a half tank of fuel in (I was in a hurry I almost always fill).

Possible things that happened??-

-Stuck injector became unstuck
-Stuck valve became unstuck
-Clogged exhaust opened up
-Fuel screen cleared

Anyways, I am glad it is back. I was worried for awhile.

mach0415 · #27 07-07-2012, 08:16 PM

Quote:

Originally Posted by Graplr

The problem mysteriously cured itself. It was behaving like this for just over a week. It was a real struggle off the line. It would literally crawl until I got to about 15 mph from a dead stop. Tons of black smoke, even noticeable at highway speeds.

Last night on the way home at about 9pm, there were no more symptoms. Smoke was gone, back to normal power off the line, idle was much better.

There was nothing specific that I did yesterday to fix the issue. I did put a half tank of fuel in (I was in a hurry I almost always fill).

Possible things that happened??-

-Stuck injector became unstuck
-Stuck valve became unstuck
-Clogged exhaust opened up
-Fuel screen cleared

Anyways, I am glad it is back. I was worried for awhile.

Good to hear. I would run some Lubri Moly Diesel Purge or acceptable equivalent through it just to be safe. I love it when things are looking down, and then all of a sudden it is a thing of the past. Hopefully, no more problems. I have literally run into a stream of 3 of my own personal cars that have needed head gasket(s) replaced - none Mercedes. Funny how things appear out of the blue. I can appreciate a simple repair.

Its funny how for years in a shop, as a tech, you may not see weird stuff happen, and then all of a sudden out of the blue, two weeks worth of weird, "out of characteristic-for-the-year-make-and-model" crap comes through the shop and trips us up.

I hope all is well beyond this for you.

Graplr · #28 07-07-2012, 08:31 PM

Quote:

Originally Posted by mach0415

Good to hear. I would run some Lubri Moly Diesel Purge or acceptable equivalent through it just to be safe.

Read post #21-

Quote:

Originally Posted by mach0415

I hope all is well beyond this for you.

Thanks, me too.

Benzkid_300D · #29 07-07-2012, 10:38 PM

Quote:

Originally Posted by Graplr

The problem mysteriously cured itself.

These cars do have a history of magically fixing themselves

I wish my interior would just fix itself

Graplr · #30 04-14-2014, 07:50 PM

Quote:

Originally Posted by Graplr

Either way, I'm not going to even consider pulling the head until I park it for the winter. If it is a valve problem, I wouldn't need to pull the head, correct?

I did a diesel purge and changed the filters last night. The clear filter has completely black on the plastic even thought there was no fuel in it. I haven't been checking them daily, but when I first started driving it amount 1.5 months ago it was clear. Now it is completely clear and I can see the fuel where as before I couldn't. It did seem to help at first but I had more symptoms today of very sluggish off the line and lots of smoke. Although the engine never died with plenty off opportunity to do so.

I do agree with Kerry that I should recheck the valves and then perhaps compression check.

I've continued to drive the car "as-is". The problem comes and goes. Mostly over the last year and a half it goes. It was very present last fall before I parked it for the winter. It was so bad I didn't want to drive it. In taking it out this spring the problem was gone...at first.

I'm almost certain it is a valve problem/air problem as I swapped the injectors with another set I had. I tested the old ones and 4/5 were spraying great. The #2 injector had a bit of a stream but mostly mist. The problem was the same (come and go).

I want to investigate the head. From the PO's compression results, #5 was the low cylinder so I would assume that is where the problem/damage is. Any guidance on what to look for? I'm not too familiar with bent valves, bad springs, etc and what to look for. Is a valve job a DIYer?