1987 190D knocking injectors

Year: 1987
Model: 190D (Turbo)
Engine: OM602
Mileage: 225,000

Problem: bad "metallic sound" - sounds like injectors knocking.

Overview:

This knocking exists at low RPM. The engine also idles very rough. It goes away when you rev the motor or place a load on the motor. If I run a thicker fuel (like clean motor oil or power steering fluid - bypassing the main tank), the knocking also almost completely goes away.

I have bled the lines. I purchased the entire injector rebuild kit (w/ new nozzles). I balanced each within 50psi. I have changed air and both fuel filters. I have removed and cleaned the main tank. I have blasted out supply and return lines (to and from) the fuel tank.

It may be worth noting that:

-> The previous owner *may* have run veggie fuel
-> The car did sit for nearly 2 years before I bought it
-> This condition exists even when the car is warmed up (running for 15 minutes).

What I have NOT done yet: reamed the glow plug holes (although I did purchase the tool). I did not think this would cause such and issue though - especially once the engine is completely warmed up.

This leaves me to believe there is an issue with the IP. If so...

-> Does mercedes source sell a IP rebuild kit?
-> If so, how hard in removal/reinstallation?
-> If so, how hard is proper timing? I hear this is a pain in the arse.

I am kinda at the point where I would almost rather have someone recommend a trusted (and good) mechanic around Nashville (or anywhere in middle TN) who will just fix this.

Please help! I have invested $1,500 thus far and my next step will be simply getting my money back out of the thing via Craigslist!

Forums

Diesel Engine Specific Aid

Chassis Model Number

W201

Recommendations

Can you still hear the knocking at 2000+ rpm. Try to isolate which cylinder or cylinders are knocking by loosening up one injector line at a time while the engine is running. If you can not tell any difference then check internal engine and injection pump timing before doing any things else. Refer to factory maintenance manual for those procedures.

>> Can you still hear the

>> Can you still hear the knocking at 2000+ rpm?

No.

Well, maybe kinda. I know the "sound" of a good diesel and I can still "hear" the ever so faint "pinging" - does sound out of time.

I have tried loosening each injector one by one. The sounds muffles a small bit regardless of what injector is loosened. Keep in mind I rebuilt all 5 injectors with the new Monarchs. In fact, I took em apart a second time and cleaned them carefully in a computer datacenter clean room.

I have come across an interesting thread here:

http://www.pointedthree.com/disc/forums/showthread.php?tid=16515

Digging into this fuel pressure relief valve thread makes sense: when I run the engine on a thicker fluid (like tranny or power steering fluid) the knock goes away. Perhaps because the thicker fluid is harder to push past this relief valve hence keeping the pressure where it should be?

I do have the actual MB engine service manual as well as Mitchell OnDemand - seems I will need several special tools for at least removal and re-installation of the IP. Even getting to the pump requires removal of the intake manifold.. looks like time to spend more money on mercedessource.com for intake gasket kit.

I understand a lot about diesel theory and operation, but I think I am gonna be getting in above my head with the IP. Timing a diesel seems much more involved than timing a gasser. Plus, screwing up the timing on a gasser does not always have as dire consequence as screwing it up on a diesel.

Sigh..