87 MB 300D Turbo will not stay running
 

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 not its 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

At best I am a rank amateur but
 

It seems to me that the crossover tube is part of the intake-not the exhaust. By removing it, the engine will run but without the crossover there is no turbo boost so you cannot get much power. I would look at the aircleaner and forward for signs of obstruction. The air intake starts in the passenger side front wheel well. If that and the duct to the aircleaner filter is clear, move on to the turbo. Those in the know say not to use starter fluid on indirect injection diesels -like the 603.

If it's been sitting that long, the exhaust may have a mouse made obstruction like fiber packing. That happened to a car that I bought years ago.

I disconnected the front flex pipe from the rest of the exhaust, and mine ran great which told me there was a blockage further back.

I agree with this ^^^ If your exhaust were blocked, removing the crossover would make no dramatic difference. I have to believe there is a blockage in the intake somewhere. Have you pulled the hose to the entrance of the turbo and tried to run it that way? Also, if smoke (exhaust) came up through where the crossover would normally be, the only (likely) way I can think of that would allow that to happen is if the EGR valve is open. Block it off.

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.

LOL...so the engine will run...with that same exhaust attached...IF the intake is open to air. But if the intake is closed, the exhaust manifold must be open to air.

Doesn't anyone screen these calls!!! :D

OK, my only theory is that the back pressure from the blocked exhaust is pushing sooty, oxygen-poor air through the EGR port, filling the intake and snuffing the possibility of combustion. Removing the crossover allows a path for fresh air and the exhaust is open just enough to allow it to run.
How's that? Otherwise, I got nuthin'. Glad you're on the right track! :vbac47679
(I still say block the EGR)

(Next you'll be saying the EGR has been blocked all along) :P

I don't think that the airbox IS the start
 

The duct from the passenger front wheel well can also be blocked by both critters and simply vegetative debris. Ask me how I know.....

How this engine WILL start with either the intake or exhaust open is pretty confusing. Your initial post indicated that you were more or less driving normally and then had to limp home while laying smoke which is what started this saga. Is it possible that running the engine caused something to get sucked into the intake tract-or pushed something down the exhaust-in either case preventing intake air or expelled exhaust from moving?

With the crossover removed, everything forward of the engine itself is removed as a choke point. The turbo just blows air into space but it still spins due to the exhaust moving down the pipe. If the crossover is in place and the cat removed, is it possible that, due to the boost which you are now getting, that air flow is at a much higher volume which allows sufficient air to make it through a potential blockage in the intake.

By the way, have you cleaned out the crossover tube? That impacts both incoming air and turbo boost.

As for the calls being screened: Click and Clack seemed to screen diesel calls pretty effectively since such calls were rare and they mostly did not know squat about diesels.

How does the air filter look? If mice got into the intake tubes, found their way to the filter and decided to turn the filter into nesting material, you could have ingested that and it could have made it all the way into the exhaust system plugging up your cat.

Check the turbo for blood on the compressor wheel, you may have ingested the whole mouse too, who knows!

I faced a serious plugged cat problem when I got my car, the engine would not run at all, the EGR port was blowing really hard as exhaust had nowhere to go. There was literally zero flow out of the tail pipe.

I think that there is some sort of connection between the crankcase pressure and the IP shutting off fuel. WHY - because I could start the engine pretty well, it would shake like an earthquake though, but would shutdown if i revved it above 2000 rpm, and would not start unless I left it to rest for about 1 hour.

Is the crossover tube loaded with oil? Maybe the turbo seal blew and it's causing it to load up with oil?

Thanks for everyone's valuable input. I have come to the conclusion that my problem was with the catalytic converter. I had about 99% blockage, not allowing any of my exhaust gas to pass through the cat. All of my exhaust was routed through my turbo and back into my intake, snuffing and choking out any combustion. Solution: Hollow out the existing cat to allow exhaust to pass through. Results: A smooth running back to "normal" vehicle. Thanks.