Ahh hem, that "gentlemen" would be me, Frankie. BTW Barry, my friend, I am a lady but of course my nick name truly is Frankie.
I am keeping a close eye on this thread and am elated, ELATED that guru got his "groove back!" I had mine parked for 5 days now. The car is definitely driveable however she still makes a hammering noise with accel faster than 40 mph and still with rough idle. This is even after I soaked that one injector in MMO as experiment in 65-70 deg F weather for about 3 days. It took very light scraping to get the carbon off. Careful not to touch the center of nose.
I am in similar situation as guru except that guru could not get his car started.
Guru please tell me, is your car making a nailing noise aside from the normal diesel clacking? I am also curious as another member asked if you re-tested your compression?
I am very happy to read much good news can happen in a couple of days on this forum. I think I will try a soak of MMO too. Guru, how much did you squirt into each injector?
I am still at stage of avoiding having to pull the engine head. Besides, my co-worker is talking to a couple of recommended diesel mechanic in my area and he wants me to have the car stay put for now. TM Allison was good enough to lend me his good injectors. His engine purrs as good as his cat does. Thanks Terry, I take care of those tools I borrowed!
Frankie

__________________
Frankie
It never ends!
1985 300D Turbo 181K Anthracite grey, "SOPHIA"
1984 300 SD Turbo(sold)
2004 Subaru Forester XT,Cayenne red.

Sorry about the gender mix up. No intent behind it. If someone accidently thought me a girl I guess I would also react. Yes I have had my rabies shots.
We both have to mark our respective territiories it seems. I have four daughters that try to keep me in line. Probably with questionable results. The wife even beats up on my head periodically. . I deserve it I imagine. Yet in my shell shocked condition it is hard to evaluate it. Five against one is only fair in their world.
Label your injectors 1-5 when you pull them to sub with the loaners. The condition of the injector nose might indicate the cylinder with a problem.
Thats if there is one. Same as is done with spark plugs. Hope it is just an injector problem.
The nailing symptom seems to point in that direction in my opinion. You may find that us guys are not always right as well though. Hard to believe this at first mention I fully realise.

Hey Barry-
No offense taken. Having a tomboy nickname comes in handy when you want to acclimate to a male dominated area without photos Nice to learn about a diesel Mercedes without running a risk of being talked down to, as I have experienced face to face with an arrogant Mercedes mechanic in my town. It turns out that my hunch was right that time.

So in your case Barry, regarding Guru, it is great to be wrong since you thought that he might need a new engine! Collective sigh of relief.
I hope my problem resolves a little faster than 2 months. I'd imagine that Guru was just about ready to give up on her. What patience!
Frankie

__________________
Frankie
It never ends!
1985 300D Turbo 181K Anthracite grey, "SOPHIA"
1984 300 SD Turbo(sold)
2004 Subaru Forester XT,Cayenne red.

Well I'm not sure what to offer for hard evidence, but Ill gladly offer the details I know. I'll call things pre-soak, post-soak 1, and post-soak 2,
Each soak was a little over a week and halfway into soak 1, I managed to get a block heater installed (stock in-block type), so the temp was up near 100F from then on.
Pre-soak:
When I first tried to start her, she let off a thick waxy smelling smoke from the exhaust manifold, the smoke would escape from a leak in the egr connector hose, that thin steel flexi hose. The smoke was exactly the smell of a blown-out candle. It would wisp up from said leak and from the oil fill cap, and would continue a minute or two after cranking. In my opinion, that smoke was friction-heated build up in the cylinders. I mentioned the smoke early in my thread as I was concerned that I wasn't cooking my starter or its wiring. The motor would turn pretty rapidly, about the same rate as a friend's 300td, but his would start right up. She has lots no, LOTS of blow-by so that's when I started wondering if there was gonna be enough compression to start or if this was an uber tired or dead motor.
So we pulled the glow plugs and they were fouled, covered in a grease like looking gunk and wouldn't heat up. I should have then figured out the prechambers were gunked, but I hoped that with new plugs she would fire. It sounded little different with new plugs, the waxy smoke continued. Pulled the new plugs to do the first compression check and they were also looking like they were dipped in black grease. 1st compression test showed 150 to 170lbs with engine cold. That's when I found this site, and inqired if that was gonna be enough compression to start her.

Soak 1
pulled the injectors and noted they looked pretty foul. I labeled them 1-5 and soaked the nozzle tips ( still in holders ) in mmo for a week at 35-50F.
The coke at tips loosened up a little, I didn't know enough to have them tested or that they even can be opened up and cleaned/ inspected. I did know enough to be carefull not to mess them up by scratching the needle or the hole. Then I sprayed a few squirts of mmo down the injector holes from a spray bottle every few hours.
I adjusted the valves and changed the fuel filters, and got the compression #s up to 300lbs. Important to note, that it was with the block heater on and with a gasoline compression tester that goes to 300lbs max. #2 cylinder was lower at 220 ish.

She was then sputtering but not starting. The smoke was greatly diminished and the prechambers were clear of gunk, the mmo did that for sure. I had the intake and exhaust manifolds off to get at the block plug, so cleaned lots of gunk out of the intake manifold (im) using mmo and kerosine. Kept squirting mmo in glow plug #2.

Soak #2
Some kind soul suggested I had a simple fuel problem. Pulled the injectors again, and noted the were full of fuel but dry at all nozzles. They were clearly clogged so I didn't bother to have them tested. I kept spraying mmo in all cylinders as before while I waited for the new nozzles to arrive, all the while keeping the block heater plugged in. Pulled injectors apart and they were nasty at tips and two looked as though they wouldn't function.
Put new ones on and bled system as mentioned. When cranking the motor the waxy smoke was now gone! Thats my best evidence that the mmo cleaned out the inside of cylinders.
She smoked alot but that cleaned up with a 30 minute drive.

There is an intermittant sound that might be described as nailing, but mostly at idle when cold. I do not hear it at higher rpm. I have yet to replace the cracked egr hose and I want to drive it with that fixed for a half a tank before I worry about the nailing.
I have not done another compression test and have no plans to.

I hope that helps, as far as patience goes I teach elementary school so I get lots of practice, but thanks. The encouragement and ideas offered here kept me going for certain.

Many times in this process I thought I might just give up and tow it somewhere and have someone else fix it or blow it up.
I hind sight, I realize I should have suspected the injectors long ago but then I wouldn't have had the time to thouroghly soak it. I also don't imagine that a shop would have the time or patience to properly address the gunk problem without removing the head.

I am now driving the Marvel Mystery Wagon daily. This cure cost me ~$400.00 in glow plugs, battery, nozzles and filters, and $5.00 for the mmo and exactly $0.00 in labor.