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  #1  
Old 10-20-2004, 04:10 PM
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Location: Okanagan Valley, BC, Canada
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Black smoke + No power = Too much fuel?

Yesterday my '87 300 SDL suddenly started spewing black smoke. It is absolutely the worst smoke-show that I have ever seen any diesel produce! Other diesels change lanes to avoid me! I'm stumped as to the cause of the smoke, but am convinced that it is an excess of fuel which is the problem (obviously!).

The car does not smoke at idle, and idles smoothly. It has very little power off the line, and does not smoke much until the revs get up to about 2000 rpm. The car will no longer upshift to the higher gears, and the engine will not rev much over 3000 or 4000 rpm when under load. It will not rev high enough to shift to the next gear (after second gear).

I teed a boost gauge into the boost line to the ALDA, and determined that the turbo appears to be working, since it produces up to 9 pounds of boost at 3000 rpm (under load). The boost increases more slowly than it did a few months ago (when I last checked), and appears to jump around a little bit as it increases (which could just be my cheap gauge).

I thought that perhaps a really dirty air filter would cause it to run rich, so I removed the cover of the air cleaner, and made a few test runs without it (it's a cool rainy day here), with no difference in the amount of boost or smoke produced. My air filter is only a few months old, but I checked this anyway.

I've been concerned about the trap oxidizer for a while (the dealer refuses to replace it) and have noticed soot accumulating on the passenger side of the valve cover in the past few days. Perhaps it's stuffed full of soot?

It seems as if the amount of blowby has increased in the past few days, also. Previously, there was NO blowby at all, and now there is noticeable, though relatively slight, blowby.

I thought perhaps the EGR could be stuck open, but I had previously removed the vacuum line, and stuffed a bb into it (the line is not connected to the EGR). I tested the operation of the EGR, by hooking up my MityVac to it. As I increased the vacuum to the EGR, the engine began to stumble, and puffs of soot began to appear between the trap oxidizer and the valve cover. I wonder if the exhaust manifold gasket is leaking? I noticed that the exhaust out the tailpipe would become darker as I increased the vacuum. If I increased the vacuum to the EGR enough, the engine would stall. I then checked to see if the EGR was closing, by pumping up the vacuum, and then suddenly releasing it. Each time the EGR closed with a satisfying "clunk".

I plan to remove the EGR and replace it with blanking plates (for testing), and am considering removing the trap oxidizer and replacing it with the replacement pipe. Can anyone tell me if the replacement pipe is a direct replacement, or if the upgraded oxidation catalyst/front exhaust pipe assembly is also required? The part number I have for the trap oxidizer replacement pipe is 603 140 03 03.

I've already searched the archives, but couldn't find any post which dealt specifically with the failure mode of a trap oxidizer.

Does anyone have any ideas about the cause of my excess fuel? Could it be a problem with the injection pump?

Sorry for the length of this post; I just want to make sure that all the information I have is made available, to ease any diagnosis.

Thanks in advance,

Richard

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  #2  
Old 10-20-2004, 04:57 PM
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Location: Bothell, WA
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Have you checked your oil consumption to make sure you're not injesting oil through the turbo?

Kevin
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  #3  
Old 10-20-2004, 05:09 PM
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Location: Manhattan, KS
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Quote:
Originally Posted by Diesel_Canuck
I've been concerned about the trap oxidizer for a while (the dealer refuses to replace it)
Uhh, I don't think the dealer has much choice on the issue. That was a factory deal and you should get a replacement pipe and a new turbo. I am sure the TSB is floating around somewhere.
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Old 10-21-2004, 05:37 PM
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Location: Okanagan Valley, BC, Canada
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KCampbell wins the prize for correctly diagnosing the cause of all my black smoke. I checked the oil and it is down to the lower mark on the dipstick. Usually it doesn't consume any oil, and now it's managed to go through 2 quarts in a day!

So, does this mean that the seals in the turbo are shot? Could this be somehow related to my trap oxidizer? Perhaps the reason that boost was building slowly and jerkily is because the impeller was spinning in a pool of oil!

I intend to replace the trap with a pipe, and remove the EGR. Should I also consider going to a European intake setup at this time?

Thanks, Kevin, for the timely (47 minutes) and accurate reply,

Richard.

Last edited by Diesel_Canuck; 10-21-2004 at 06:02 PM.
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  #5  
Old 10-21-2004, 06:29 PM
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Dieseldiehard
 
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Location: Bay Area No Calif.
Posts: 4,299
The Euro intake would look great but not be any better performance-wise than the non-EGR OEM intake. I would also remove the crossover pipe if it hasn't been off under your ownership, to see if its getting plugged up.
The turbo certainly needs to be removed and serviced (new cartridge and balanced) based on the intermittent pressure readings you noted and the oil consumption.
BTW if you ask for it, the rebuilders will powder coat the turbo body while it's being rebuilt (that may add a couple of days to the turn around time) It will look better because it won't get all rusty like they get otherwise.
Dieseldiehard
1971 220 (gas) 4-spd manual 106441
1979 300TD w/ 85 turbo engine 295530
1983 300D 243280
1985 300TD 217300
1987 300D 258230
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  #6  
Old 10-21-2004, 06:36 PM
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Take it back to the dealer, the trap oxidizer is now plugged -- soot in the engine compartment means that the seals on the exhaust have blown from excessive pressure in the exhaust.

The turbo is shot from chunks of the trap oxidizer blowing through it.

If that dealer won't do the work, take it to another or call MBUSA and get them to back you.

Under NO circumstances do the replacement yourself, it voids the exended warrrenty and the parts are NOT cheap. You will get a new turbo, a trap catalyst, and a new pipe for nothing.

Peter
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1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
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  #7  
Old 10-21-2004, 06:48 PM
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Dieseldiehard
 
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Location: Bay Area No Calif.
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yes, he tried dealing with MB Canada but they refuse saying it is something MBNA has responsibility for. I told him drive the car to Calif and have it done by a MBNA dealer. I also said I would baby the car and let him drive one of my fleet if the car would make it this far (No Calif) which now it won't so its down to negociations with the dealer, and if unsuccessful have the work done at his expense. Pity. I'm dissappointed to hear MB Canada is so rigid.
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  #8  
Old 10-21-2004, 10:52 PM
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Location: Bothell, WA
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Quote:
Originally Posted by Diesel_Canuck
KCampbell wins the prize for correctly diagnosing the cause of all my black smoke. I checked the oil and it is down to the lower mark on the dipstick. Usually it doesn't consume any oil, and now it's managed to go through 2 quarts in a day!

So, does this mean that the seals in the turbo are shot? Could this be somehow related to my trap oxidizer? Perhaps the reason that boost was building slowly and jerkily is because the impeller was spinning in a pool of oil!

I intend to replace the trap with a pipe, and remove the EGR. Should I also consider going to a European intake setup at this time?

Thanks, Kevin, for the timely (47 minutes) and accurate reply,

Richard.
I am genuinely, sincerely, sorry to have guessed correctly in this case.

Kevin

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