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 01-12-2017, 11:48 PM
Registered User
 
Join Date: Jun 2006
Location: Southeast
Posts: 1,848
Timing chain choices, which is the right one?

I've heard different stories from different people and mechanics. Just wanted to see what advice I get here for my 1991 300d 602 engine with 210k miles.

1) Some people just check for chain stretch, adjust it, and that's it. Others say to replace the chain, rails, and tensioner. An article I just read said to replace the sprocket too.How many have replaced the sprocket?

2) A general mechanic is going to check the timing chain for stretch, or he can replace the chain for an additional $250. Does the chain need to be replaced?

3) One MB independent mechanic told me not to replace the chain. He said he has never seen a chain break on W124's; they are dual chains and they're NOT going to break. He also told me he checks for stretch through the injection pump, and that there was a service bulletin out that the injection pump also needs to be altered by 1 degree.

....So....what to do? Just check for stretch? Or replace parts? If so which ones? Is a new chain really necessary?

Reply With Quote
  #2  
Old 01-13-2017, 10:07 AM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Posts: 6,025
A new chain is only necessary if it is worn. Checking stretch is a reasonable method of checking (the chain doesn't actually stretch, it wears and the tolerances add up to a longer chain). The life of the chain has a lot to do with the driving style it has been subjected to and how well the engine has been maintained. If the oil change interval has been too long, used cheap oil, or drove aggressively all the time then the chain will wear faster.

The sprocket doesn't need to be replaced unless the teeth are worn. They're normally a square profile and fit fairly snugly in the spaces in the chain. If they're worn pointy or "sharp" get a new sprocket, it'll wreck the new chain. Unless the chain is really stretched and has been neglected for a LONG time, it's unlikely that the sprocket is bad.

For what it's worth, my SDL has the 6 cylinder 603 with more surely more miles than the Odometer says, and both the chain and sprocket in mine were still good. The cam timing is non-adjustable on the 60x engine. On the 61x you could use an offset woodruff key to "correct" the timing. The 60x uses a dowel pin to locate the sprocket to the cam and is not adjustable.
Reply With Quote
  #3  
Old 01-13-2017, 03:56 PM
Registered User
 
Join Date: Jun 2006
Location: Southeast
Posts: 1,848
Do you think the rails and tensioner should be replaced?

Quote:
Originally Posted by Diseasel300 View Post
A new chain is only necessary if it is worn. Checking stretch is a reasonable method of checking (the chain doesn't actually stretch, it wears and the tolerances add up to a longer chain). The life of the chain has a lot to do with the driving style it has been subjected to and how well the engine has been maintained. If the oil change interval has been too long, used cheap oil, or drove aggressively all the time then the chain will wear faster.

The sprocket doesn't need to be replaced unless the teeth are worn. They're normally a square profile and fit fairly snugly in the spaces in the chain. If they're worn pointy or "sharp" get a new sprocket, it'll wreck the new chain. Unless the chain is really stretched and has been neglected for a LONG time, it's unlikely that the sprocket is bad.

For what it's worth, my SDL has the 6 cylinder 603 with more surely more miles than the Odometer says, and both the chain and sprocket in mine were still good. The cam timing is non-adjustable on the 60x engine. On the 61x you could use an offset woodruff key to "correct" the timing. The 60x uses a dowel pin to locate the sprocket to the cam and is not adjustable.
What about rails and tensioner? The car has 210k on it. I'm thinking if the tensioner looks good.....the next time this car will be checked will be in another 200k and the tensioner could start to fail in 40k from now for all I know.
Reply With Quote
  #4  
Old 01-13-2017, 04:00 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 51,038
If someone has not already mentioned it only use a IWIS (looks like JIWIS on the chain).

It is not a good idea to let the Mechanic substitute another make of timing chain.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #5  
Old 01-13-2017, 06:41 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Posts: 6,025
The tensioner doesn't have much to it. A couple springs, a piston, and a couple of ball bearings. There isn't really anything inside to go wrong except for varnish buildup. I tore down the tensioner in my SDL and cleaned it in solvent. Nothing was worn internally.

Rails are down to how worn they are. If they aren't worn out, leave them. If they're looking sad, replace them.
Reply With Quote
  #6  
Old 01-14-2017, 01:17 PM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 3,115
Don't know the 602, but in my 603 engines I used an offset key on the camshaft sprocket. Simple, and I have no concerns that the chain will ever break.
__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans
Reply With Quote
  #7  
Old 01-14-2017, 02:54 PM
Diseasel300's Avatar
Registered User
 
Join Date: May 2016
Posts: 6,025
Quote:
Originally Posted by BillGrissom View Post
Don't know the 602, but in my 603 engines I used an offset key on the camshaft sprocket.
You sure about that? The FSM shows a locating dowel (no key) for the 603 and my SDL's engine mirrored that of the FSM.
Reply With Quote
  #8  
Old 01-14-2017, 02:58 PM
Stretch's Avatar
...like a shield of steel
 
Join Date: Sep 2009
Location: Somewhere in the Netherlands
Posts: 14,461
...make sure you reset the tensioner properly...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!
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 01:16 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page