Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-25-2011, 06:32 PM
mach0415's Avatar
Diesel Weasel
 
Join Date: Mar 2010
Location: Lawndale, NC
Posts: 648
She's got the jitters, captain

Hello all. I have noticed a rough idle and a mild skip, lately that appears to show up after the engine warms up. Tailpipe smoke usually accompanies this - bluish. The fuel and air filters were replaced recently. I did a Diesel Purge at that time, too.

So, I set out to perform my annual valve adjustment and found all the exhaust valves tight and a few of the intake valves passable, but I loosened them up a little, anyway. I noticed no change in the rough idle/skip.

Then, I continued in the diag process and loosened each of the injector lines - one at a time- to see if I could isolate the alleged cylinder. The engine responded to each of the injectors being loosened, so I wondered if injector balance could be the issue. I decided to perform a compression test while the injectors were out and found 420psi -across the board- on a warm engine.

I put a set of used injectors from a spare engine in (not rebuilt or pop tested) and started the engine. The smoke is gone, but the rough-idle- while-hot issue still exists.

I feel like I have accomplished a lot of maintenance tasks today, but I have not resolved the original concern. I am happy to see those compression numbers.

Sooo...is my concern actually related to a rack dampener problem? Can a rack dampener cause a pseudo rough idle/near skipping hot idle concern? It smooths out above a 750 rpm idle. OR Is it an IP element/IP timing symptom?
__________________
Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi
Reply With Quote
  #2  
Old 05-26-2011, 08:51 AM
layback40's Avatar
Not Banned
 
Join Date: Nov 2009
Location: Victoria Australia - down under!!
Posts: 4,023
Mark,
I dont know about the damper, but it is unlikely that its an IP timing problem. Element or DV is a possibility but its strange that it isnt just one. A check of the damper is probably a good idea. whats the timing chain tensioner like?
__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
Reply With Quote
  #3  
Old 05-26-2011, 09:15 AM
toomany MBZ's Avatar
Registered User
 
Join Date: Nov 2006
Location: central Va
Posts: 7,820
Quote:
Originally Posted by mach0415 View Post

Sooo...is my concern actually related to a rack dampener problem? Can a rack dampener cause a pseudo rough idle/near skipping hot idle concern? It smooths out above a 750 rpm idle.
Yes.

Adjust or replace the rack damper bolt.
__________________
83 SD

84 CD
Reply With Quote
  #4  
Old 05-26-2011, 09:52 AM
mach0415's Avatar
Diesel Weasel
 
Join Date: Mar 2010
Location: Lawndale, NC
Posts: 648
Quote:
Originally Posted by layback40 View Post
Mark,
I dont know about the damper, but it is unlikely that its an IP timing problem. Element or DV is a possibility but its strange that it isnt just one. A check of the damper is probably a good idea. whats the timing chain tensioner like?
Timing chain and tensioner is original. I did the rough, inaccurate way of checking. It has 5 degrees of play in it, and will need to be replaced soon, so there is a difference in injector timing, I'm sure. i will check the damper and go from there.

My understanding is that the 85's had a different design rack damper from earlier year models, right? Can they be adjusted? or Do you replace only?
__________________
Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi
Reply With Quote
  #5  
Old 05-26-2011, 10:15 AM
mach0415's Avatar
Diesel Weasel
 
Join Date: Mar 2010
Location: Lawndale, NC
Posts: 648
Ok. I just adjusted the rack damper and it has gone away ... for now. I will drive it and see how it does over night.
__________________
Thanks,
Mark in NC

"Spark plugs?...We don't need no stinking spark plugs!"
1985 300SD "Der Silberne Schlitten" 420,000 mi


Wish these were diesel:
2003 Ford Club Wagon 130,000 mi
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 02:58 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page