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1987 300d Turbo
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Discussion Starter #1
Good day to all. I am new to the forum and new to diesels in general. I have owned a MB 1987 300d Turbo for more than two years with little to no troubles. I had the car parked for a little over a year, I would start and try to drive it around the block monthly with no problems. I replaced the glow plugs while it was on hiatus with no troubles. Last week I decided I was going to make her my daily driver again and drove her up to get registered, I noticed a little power loss and black smoke coming from the exhaust. And ended up limping her home. By time I was home, there was little-to no power and tons of black exhaust smoke. Now she doesn't start at all. I assumed and thought maybe I sucked up some bad diesel from letting her sit for so long. So I changed all the fuel filters, including the tank screen. I pulled the tank out and flushed it. Pulled the sending unit and cleaned it. Blew out the fuel lines. Pulled and tested the injectors, (good pop pressure and spray pattern). Got it started but still no power and lots of black soot from the exhaust, then it died and now its not starting. I have bled the lines and injectors, I've tried starting fluids, and WD-40, with no luck. After reading a few different forums I realized I could try to spray starting fluid directly into the manifold with the crossover tube disconnected. After about 20-25 sec of continuous cranking it started. Blew some smoke out of the turbo hit the pedal and lots of power. Turned it off and then started it again with no problems. Went to hook up the crossover tube and it died, choked out. It will not start or run with crossover tube connected, (no problems with it disconnected). What I thought to be a fuel delivery problem has turned out to be a possible exhaust problem (?, nesting), now I am at a loss of what to do next. Any help on what to do next would be great. Pleases and Thank Yous provided.

Known New Parts:
Glow Plugs
Pre-Filter
Main Filter
Tank Screen
Tank Screen Fuel Line
Fuel Injector Seals
Air Filter
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,395 Posts
My first guess would be fuel contamination (make sure all 3 filters got changed) or possible compression problem.

Remember, diesels are compression enginess. Without very high compression, they won't run no matter what type of fuel you're pushing though.
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
Do not use starter fluid in these engines.

Virtually guaranteed that this is a fuel related issue. Start with the basic fuel filters and then the tank strainer.
 

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1992 300D 2.5T (124.128) 1999 S320 SWB (140.032) 1999 E320 4Matic (210.082) 1984 300CD (123.153)
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177 Posts
If there is a lot of black smoke, fuel delivery is not the issue. Black smoke is from over-fueling / not enough air. Your engine needs fuel, air and compression / heat to run. If it was running when parked, it should still run. The head gasket didn't go bad from it sitting. You said that you changed all of the fuel filters and flushed the tank...well, I didn't think it was a fuel issue at the beginning of your post, and with all of that done, I am 99% sure that it is getting fuel. Since it ran with the crossover pipe off, and died with it on, that tells me that the engine is starving for air. My guess would be that because it sat for so long, some critters built a nest in the air box or the air intake duct. Take all of the intake side apart and clean everything.
 

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'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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Fuel delivery issues can produce black smoke if the spray pattern is improper or suffering from insufficient fueling levels. Critters in the air cleaner is also an excellent source of problems associated with extensive sitting.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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Sometimes the nozzle on the prechamber clogs up causing poor injection patterns. This is especially common in circumstances where the engine is used for short haul duty, never gets a diesel purge or god forbid is forced to run on waste veg oil.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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When the engine runs fine with crossover piece removed - it can't be fuel problem.
You have bad air restriction on intake. Pull the turbo intake hose and check for mouse nest.
IF there is a air intake restriction, it is far more likely to be between the fender and the air box. A restriction beween the airbox and turbo is virtually impossible, unless you had the air filter removed while the car was in storage.

Another culprit could be a clogged oxidation catalyst or the classic Eddie Murphy "banana in da tailpipe'. The clogged catalyst was my diesel's performance issue when I bought it. Poor thing couldn't even move out its own shadow until I cut out the catalyst and welded in bypass pipes.

Since you have a 87, do you have the updated exhaust system w/ catalyst or the factory intalled oxidizer trap??? Best way to tell is by looking just aft of the turbo, If the downpipe looks like a football, you have the original. The updated system has a normal looking downpipe.
 

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1992 300D 2.5T (124.128) 1999 S320 SWB (140.032) 1999 E320 4Matic (210.082) 1984 300CD (123.153)
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177 Posts
The trap oxidizer is a good thing to check, but I have not seen an '87 that still has one installed in years. I think by now all of them have been changed out to the new setup without the trap.

Also, since the car runs with the crossover pipe removed, it is almost certainly an air restriction.

As sbaert says, it is unlikely the restriction is in the turbo intake pipe, but not impossible. Mice can easily chew through the air filter and get into that pipe. Pull that pipe all the way off of the front of the turbo, and clean it out, and also remove the air box and remove any debris that may be in between the fender and the air intake. Make sure nothing has gotten into the turbo impreller, because if there was a mouse nest in that pipe and you get it sucked into the turbo, you will be in for a bad day to say the least.
 

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E320/E250 Bluetec Ford F350 6.7l
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36,722 Posts
IF there is a air intake restriction, it is far more likely to be between the fender and the air box. A restriction beween the airbox and turbo is virtually impossible, unless you had the air filter removed while the car was in storage..
Don't you just love it?
My wife makes crosswords puzzles, but they can be extremely stupid, while this puzzle is real life action and can be actually productive.
Would we be allow put actual bets on our guesses, that might be even more exciting :D
 

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1987 300d Turbo
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3 Posts
Discussion Starter #12 (Edited)
Thanks to all who helped out in getting me diagnosed. I too believed it to be an intake problem as well. I started at the front with the airbox and found nothing restricting the air flow. I then moved to the rear mufflers. Both had no blockages that could be seen (still no start). Next I dropped the CAT and flex pipe, and she started right up. I can only assume that my problem lies within the CAT or the pipe. But you know what they say about assuming, it makes an ASS out of U and ME. The CAT is welded onto the pipe and looks extremely dirty. I'm going to replace it this week, (hopefully just the CAT). I will keep this post updated with my results. Again thanks to all who helped out.
 

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'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
You can "core" out the cat by ramming a long metal rod in there to break up the matrix. I did this on my 603 and saw no gain in power, but others have indicated that it freed up the engine to rev.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,395 Posts
Being a diesel, your car has a oxidation catalyst which works diffferently than a standard catalytic converter although both serve the same purpose (detoxification).

The cheapest solution is to have a exhaust shop cut out the clogged catalyst and substitute automotive grade stainless steel pipe.
 

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1987 300d Turbo
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3 Posts
Discussion Starter #16
Thank you to all in your help of getting my Benz on the road again. I took some of the advice of the members here to hollow out the CAT. Our vehicles have to pass emissions here, so i decided against a straight pipe. The CAT was so clogged, it was pushing all of the exhaust gasses through the turbo and into the intake manifold. There was like 99% blockage. benz cat honeycomb.jpg .
 

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E320/E250 Bluetec Ford F350 6.7l
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That explains it, although the turbo has to be really bad for such a leak.
Exhaust gases having no flows via the CAT recirculate into intake manifold and the engine will not run on exhaust.
Where are you? We do have to smog our 1998 and newer diesels in California, but nobody puts sniffer into the pipe.
 

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If any air flows through the turbo like that it would be amazing that it ran at all as the turbo would have to be such garbage that metal parts would have to have been inhaled by the engine. Nevermind the oil pressure loss....

I think he meant it got pushed through the EGR. Much more likely of a pathway, and it doesn't require catastrophic failure.
 
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