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Old 02-07-2014, 08:57 AM
Gregory Gregory is offline
Registered User
Join Date: May 2005
Location: Twin Falls, Idaho
Posts: 330
Originally Posted by Jooseppi Luna View Post
The rough idle may be an altogether separate issue. Is the idle jumping around, or is it mainly shaky? If it's mainly a rattling-your-teeth-out (or rattling-your-dentures-out if you've ignored it for long enough) issue, the most common culprits are:

Motor mounts
Engine shocks
Nailing injectors
Rack Damper Bolt
Maladjusted valves
Filthy engine

For motor mounts, Roy (whunter) has specified a way to test for them that I can't remember right now. The engine shocks I would leave for now. Rack damper bolt adjustment instructions are here:

1985 300D Rack Damper Adjustment.

Valve adjustment instructions are all over the net, and the filthy engine could be corrected via a diesel purge -- DieselGiant has a great set of instructions, but know that NAPA carries that purge fluid for MUCH less than DieselGiant.

EDIT: Ha, I forgot nailing. Nailing injectors have a distinct clicking sound that can be heard over the general engine rattle -- kind of like the gnome who lives under your valve cover and makes the engine work right is building himself a house . If your injectors are nailing, I recommend greazzer for the rebuild unless you want to do it yourself, at which point you'd need to find a pop-tester somewhere.
The idle is rough and noisy, maybe nailing. Reving up a bit stops the odd noise and it runs smoother. I drove it as-is from southern Arizona to southern Idaho, it did ok, except for leaking a quart of oil. New lower oil line arrived yesterday for that problem.

The PO gave me a receipt for two motor mounts and the tranny mount. I'm guessing he installed them.

The engine shocks are there, but the lower mounts for them are in the trunk. Not sure if they are good or need to be replaced.

I bought 5 used injectors and sent them to greazzer for R&R. He is working on them now.

Rack damper bolt and valve adjust are other unknowns right now. Its 20F outside and snowing. I don't have a garage so this project is stalled for a while.
1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI
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