87 300SDL Power Loss, Smoke - PeachParts Mercedes-Benz Forum

Gregory · #1 10-22-2008, 04:50 PM

I was driving highway speed for an hour and saw I was going to be late, so I bumped it up to 90 mph for a 1/2 hour.

After my meeting, I was getting back on the freeway and it was sluggish, and a lot of grey smoke was coming out.

I drove it for 90 minutes, it would barely go 80 mph, it usually zips right up to 100, no problem.

I took the air tube off the front of the turbo and got my finger in there. The blades spun freely, and I could not detect any wobble or axle play. There was a small puddle of oil in the turbo housing, in front of the blades.

It smokes the most when trying to accellerate. When backing off the throttle, the smoke stops.

This problem came on suddenly, there was no slow loss of power over time.

The car has 260,000 miles. The EGR has been blocked off with a copper sheet for a couple years.

babymog · #2 10-22-2008, 04:54 PM

Does it run and idle smoothly? Sounds like a nozzle has failed, but it would certainly idle rough.

Gregory · #3 10-22-2008, 04:56 PM

It starts the same as before. It idles ok, no shaking.

Could it be an injector that is stuck open?

babymog · #4 10-22-2008, 05:00 PM

Not likely, if the injector was stuck open it would inject early and not spray well = rough idle.

Gray smoke is usually slight overfueling, does the car roll freely?

Jadavis · #5 10-22-2008, 05:00 PM

Could it be as simple as a bad batch of fuel? Cruddy fuel and clogged filters would explain what you are seeing.

If you came in near empty and then filled up with a full tank of bad fuel it would explain the sudden onset.

-Jim

sixto · #6 10-22-2008, 05:01 PM

Maybe the line from the manifold to the ALDA got knocked off or there's something clogging the line.

Sixto
87 300D

Gregory · #7 10-22-2008, 05:06 PM

The car rolls freely.

I did stop 1/2 way home and filled it up. At that time I put in 3-4 oz of Diesel-Kleen. It was smoking before and after that fill-up

A few months ago, I changed the two fuel filters in the engine compartment, but didn't change the tank filter.

I replaced the #2 line from the fuel pump to the injector last month. I just now noticed that it is weeping a very small amount of fuel at the #2 injector line connection.

C Sean Watts · #8 10-22-2008, 05:08 PM

If you still have the under body trap oxidizer, there is a chance it has soot blockage. I 'cleaned mine out'

and welded the shell back on. In case you were wondering, it comes out in one piece and photos should come soon. After operation 'clean out' - BIG improvement. I have not had it back on the road long enough to see if the smoky sluggishness happens again. I did to a very brief Italian tune up and for a few seconds I looked like a 'double naught spy' blowing a smoke screen. It even ran smoother afterwards.

Brian Carlton · #9 10-22-2008, 06:46 PM

Quote:

Originally Posted by Gregory

It smokes the most when trying to accellerate. When backing off the throttle, the smoke stops.

This shows the lack of sufficient air.

Check the intake and the air filter for obstructions. Check the airflow meter for anything that prevents movement.

Gregory · #10 10-22-2008, 07:28 PM

I checked the vacuum lines to/from the ALDA.

There is one that goes to the middle of the intake manifold, I took it apart and blew air through it to make sure it wasn't clogged. I poked a toothpick into the openings to make sure they weren't clogged.

I don't see any obstruction in the air intake and filter box.

Gregory · #11 10-22-2008, 08:33 PM

The smoke is pretty impressive in the rear-view mirror when the sun is low behind the car.

compu_85 · #12 10-22-2008, 08:51 PM

A broken ALDA line would make the car slow, but it wouldn't smoke. It would be as smoke free as possible actually, it would never add fuel when boost came up.

-Jason

Gregory · #13 10-24-2008, 05:55 PM

I read through a lot of older threads.

Today I revved it up in park to 3000 rpm or better while looking at the actuator rod for the waste gate. It never seemed to move at all.

The arm on the waste gate points perpendicular away from the line of the engine. It points towards the right front wheel. Is that its normal rest position, or is it stuck open?

It was smoking pretty good and the smoke smells like fuel, not oil or antifreeze.

Any ideas on this?

Gregory · #14 10-25-2008, 01:44 PM

I took the car to the muffler shop. They drilled a hole in the exhaust pipe ahead of the trap oxidizer and the cat. They pressure tested the exhaust and determined that there was not anything clogged. Then they welded the hole they drilled closed. They also played around with the linkage for the waste gate, and said it moved properly, but they didn't do a pressure test on the accuator to see if it is working.

I tightened up the #2 fuel line at the injector where a little fuel was weeping.

I took it out for a speed run. It was slow in shifiting, it would get up to almost 5000 rpm before shifitng, but I was pedal to the metal because I wanted high revs, in case the Italian tune up worked.

There is a definite loss of power between 1500 and 2300 rpm, after it passes 2300, it seems to pick up a bit more. After the car is moving 15 mph, there is a lot of black smoke. At 75 mph, and not trying to accellerate any more, the smoke is a lot less.

I took some photos of the engine. One is of the exhaust pipe after the manifold. It looks like the replacement part for the original football trap oxidizer. Is there anything inside that part which could cause problems?

The other photo os of the linkage to the waste gate arm. Can someone say if it is in the correct resting position? Or is it stuck open?

sixto · #15 10-25-2008, 02:00 PM

Wastegate stuck open is not going to cause smoke.

You said the turbo shaft spins freely. Did you detect any axial or radial play? A hair's width of radial play is typical. Any axial play is bad.

Sixto
87 300D