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 10-17-2020, 01:35 AM
Registered User
 
Join Date: May 2008
Posts: 206
Shaky idle after stopping abruptly??

This 83’ 300DT has had this issue for years. Never could figure it out on my own.
Maybe it’s worse now after I redid the head? It idles great when just slowly putting around town. Only has this prob when braking hard.

Still shakes at idle after adjusting valves, injection timing, replacing fuel filters, purging the injection pump, having Greazzer rebuild injectors, new OFV spring, putting in Lemforeder mounts, adjusting the throttle linkage. What else is there?

I’d compression test, but it idles perfect when not being driven like an ape

Ideas?

Reply With Quote
  #2  
Old 10-17-2020, 07:07 AM
Registered User
 
Join Date: Apr 2004
Location: Chicago
Posts: 198
I don't see Rack Damper on the list. Suggest doing a search on that term. My wagon had the same annoying issue. Between a valve adjustment and adjusting the rack damper the issue is pretty much gone.
Reply With Quote
  #3  
Old 10-17-2020, 08:31 AM
Registered User
 
Join Date: May 2008
Posts: 206
I have replaced the rack damper and those mini shocks before as well, but it was several years ago.
If these were failed, wouldn’t it have shaky idle at all times?
Reply With Quote
  #4  
Old 10-17-2020, 01:15 PM
Registered User
 
Join Date: Oct 2012
Posts: 5,494
You stop fast the fuel moves. If there is a pocket of air the mass of the fuel can displace it. To have that fast a response the pocket of air would have to be in the injection pump. I would install a clear line from the relief valve to see if any air is showing up.


Of course I am not certain this is the issue. Installing a clear line is not that involved to observe though.
Reply With Quote
  #5  
Old 10-17-2020, 01:27 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 37,378
What is your idle speed? On mine there is a sticker that has the min and max idle speed. An engine with some wear on it may need a little more then max idle speed.
re-adjust idle speed and damper. Back out the damper till it has no effect on the idle. Adjust the idle speed. Then slowly turn in the damper screw. The goal is to remove as much shaking as possible with out raising the idle speed.
When I replace my Rack Damper/Governor Idle Pin the old one had a worn tip on it and the spring tension seemed to be about 1/2 as much.

Does your issue only show up after the Engine is up to temp and running say after 15 minutes?

What type of driving do you do. Mine drones around town and seldom gets on the Freeway.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #6  
Old 10-17-2020, 01:33 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 37,378
Quote:
Originally Posted by barry12345 View Post
You stop fast the fuel moves. If there is a pocket of air the mass of the fuel can displace it. To have that fast a response the pocket of air would have to be in the injection pump. I would install a clear line from the relief valve to see if any air is showing up.


Of course I am not certain this is the issue. Installing a clear line is not that involved to observe though.
Actually he could see if the issue is still there or lessened when he has a full tank of Fuel.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #7  
Old 10-17-2020, 04:05 PM
Registered User
 
Join Date: May 2008
Posts: 206
I’ve never tinkered with the rack damper. Will research that
Idle speed is at about 6-700.

Only does this after 15 min+ driving. When its cold, it’s nice and stable. Usually I drive 5 street, then hop on the highway for 10 mi. Occurs when I get off the highway hot
Reply With Quote
  #8  
Old 10-17-2020, 07:10 PM
Registered User
 
Join Date: Apr 2004
Location: Chicago
Posts: 198
From my own experience, my 300TD did not exhibit a constant shake. The shake was intermittent and most pronounced after exiting a highway and promptly being stopped at light.
Reply With Quote
  #9  
Old 10-17-2020, 08:36 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 37,378
Quote:
Originally Posted by gottarollwithit View Post
I’ve never tinkered with the rack damper. Will research that
Idle speed is at about 6-700.

Only does this after 15 min+ driving. When its cold, it’s nice and stable. Usually I drive 5 street, then hop on the highway for 10 mi. Occurs when I get off the highway hot
That could be part of the issue. The Emission Sticker on mine shows 750 plus or minus 50 rpms. You particular engine might benefit from the 800rpms. Some Engines may need higher.

In your case you could leave the rack damper where it is and simply use the Idle Adjusting Screw to raise the Idle to 800 rpm and see what happens.

Attached pic of my emission sticker.
Attached Thumbnails
Shaky idle after stopping abruptly??-emission-sticker-idle-speed-other-stuff.jpg  
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #10  
Old 10-17-2020, 11:19 PM
pawoSD's Avatar
Dieselsüchtiger
 
Join Date: Oct 2004
Location: Grand Rapids, MI
Posts: 15,368
I always had my 617 idle around 750-800. Significantly smoother, and better spool up off the line when punching the throttle.

Also sounded better.
__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 94k - mine - (OC-97,400)
'17 Metris(VITO!) - 19k - wifes (OC-25k)
'01 E320 Wagon - 161k - mine (OC-165,000)
'07 E350 Wagon - 138k - dad's (OC-139,500)
'01 SL500 - 84k(km) - dad's (OC-94,000km)
'16 E400 4matic Sedan - 93k - Brothers (OC-98,500)
Reply With Quote
  #11  
Old 10-18-2020, 12:08 AM
ykobayashi's Avatar
Registered User
 
Join Date: Jun 2005
Location: Irvine, CA
Posts: 714
You may want to check your tank screen. Not sure if you meant that when you said you replaced filters. A long time ago a buddy had a rag floating around in his tank that would make the car run rough at odd times when it moved about in there. Just a thought.
__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 250k miles
85 300D Turbodiesel 165k miles
Reply With Quote
  #12  
Old 10-18-2020, 07:18 PM
Registered User
 
Join Date: Oct 2012
Posts: 5,494
Quote:
Originally Posted by gottarollwithit View Post
I’ve never tinkered with the rack damper. Will research that
Idle speed is at about 6-700.

Only does this after 15 min+ driving. When its cold, it’s nice and stable. Usually I drive 5 street, then hop on the highway for 10 mi. Occurs when I get off the highway hot


This is perhaps also typical of a rack damper bolt being worn or out of adjustment. Yet that should not be braking dependent. Read up on the rack damper bolt in the archives. It is adjustable.

Last edited by barry12345; 10-18-2020 at 07:39 PM.
Reply With Quote
  #13  
Old 10-19-2020, 02:05 AM
Registered User
 
Join Date: May 2008
Posts: 206
Well, didn't go as planned.

I warmed it up, then went to adjust the silver colored RD. Found that it's fully adjusted in, so there's no more to adjust. I backed it out a couple threads just to see if that helps. Will report back after a few miles.

What happens if the bolt is too far IN?

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 05:17 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, 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