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 01-27-2018, 12:40 AM
Registered User
 
Join Date: Jan 2012
Posts: 79
Turbo advice on '85 300TD

Greetings. We have an '85 300TD with 180k miles. My son has inherited the car from me and is his daily driver. We have replaced many of the key components, and are now Looking at fixing the turbo. The turbo has not functioned "normally" for several years, but we have not messed with it since the car runs great. I personally know how the car used to perform and the sound it made when it was working correctly. There has not been any "whine" or noticeable boost for some time now.

Visual inspection the other day shows that the turbine is spinning even at idle. I don't know if that is normal. I'm just a somewhat-experienced shade tree mechanic, but it would make more sense to me that the turbine would only spin when the turbo was engaged. Is that correct?

I'm wondering if perhaps there is maybe a valve stuck open (waste gate? apologies for lack of the proper knowledge and terminology). Wondering if there are some suggestions on how to test this (vacuum or pressure from the connected lines)?

We have had the car for >15 yrs and it's pretty clean, including the engine, and we have replaced most all vacuum lines under the hood, so there's not much visually that looks corrupt.

Thanks in advance for any suggestions and help!

Reply With Quote
  #2  
Old 01-27-2018, 10:18 AM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
In the archives there are several really good threads on fixing the turbo.. which is a very simple device and new bearings and rotor were very affordable the last time it was discussed...
Reply With Quote
  #3  
Old 01-27-2018, 10:29 AM
tyl604's Avatar
Registered User
 
Join Date: Feb 2008
Location: Atlanta, GA
Posts: 3,235
If you have a bad switchover valve, it could also be the problem. It gets clogged up over the years and seriously affects the pickup. Just be sure to watch which plastic tube goes to which nipple and leave one nipple open to the atmosphere.

Might not be your turbo or this might be an additional problem.
Reply With Quote
  #4  
Old 01-27-2018, 11:15 AM
Registered User
 
Join Date: Dec 2006
Posts: 3,479
The turbo will spin whenever the engine is running. It doesn't "engage" like a gear, it just spools faster as exhaust flow increases.

There are two possibilities. One is that there is some problem with the wastegate. I believe your model has a pressure operated wastegate, which is usually pretty foolproof. But the gate itself can become rusted in place. Often this can be repaired without removing the turbo by unclipping the actuator, spraying oil on the pivot, and working it free by hand.

But the more likely (usual) problem is that the pressure sense line or the switchover for the ALDA has become clogged. You can find a photo how-to here:

dieselgiant (DOT) com/mercedesaldaboostsystemservi.htm
Reply With Quote
  #5  
Old 01-28-2018, 03:56 PM
Registered User
 
Join Date: Jan 2012
Posts: 79
Thanks
Reply With Quote
  #6  
Old 01-28-2018, 04:05 PM
Registered User
 
Join Date: Jan 2012
Posts: 79
Banjo bolt is fine

I have checked this a couple,of times, and there is no soot on it. Blows clear.

Am I correct in understanding the there should be pressure (not vacuum) on the ALDA? What would be the method for testing? (I have a pressure/vacuum gauge to,use).

Thanks.
Reply With Quote
  #7  
Old 01-28-2018, 07:37 PM
Rogviler's Avatar
Unpurist
 
Join Date: Apr 2011
Location: Colorado
Posts: 705
More advice in your duplicate thread, FYI:

Turbo advice on '85 300TD

-Rog
Reply With Quote
  #8  
Old 01-29-2018, 03:29 PM
Registered User
 
Join Date: Dec 2006
Posts: 3,479
Quote:
Originally Posted by pinpoint View Post
I have checked this a couple,of times, and there is no soot on it. Blows clear.

Am I correct in understanding the there should be pressure (not vacuum) on the ALDA? What would be the method for testing? (I have a pressure/vacuum gauge to,use).

Thanks.
Really simple. Remove the hose from the alda and plug it into your pressure gauge. There will be close to zero pressure at idle, and it will rise with RPM's. If this isn't happening, the flow path is obstructed with soot.
Reply With Quote
  #9  
Old 01-30-2018, 11:23 AM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,543
You should keep your questions in one post. The info people relate here is intended for everybody (not just you), and hard for others to find when spread over duplicate posts.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans
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 10:02 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, 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