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 04-14-2009, 12:03 PM
Registered User
 
Join Date: Mar 2008
Posts: 274
Low compression - synthetic?

I have read posts here about using synthetic oil to help clean out the engine and possibly raise compression. Just wondering if this would be a good idea in my case. The first three cylinders are about 300. The last two around 160. It starts on cold days no problem but is always jumpy until it warms up. Was thinking of trying synthetic to see if this helps as I think car sat awhile before I got it, but would this possibly bring out other problems? I'm about to take this car on 1-2000 mile road trip and don't want to do anything that might cause problems.

__________________
1980 300D, 128K
Reply With Quote
  #2  
Old 04-14-2009, 12:32 PM
Stevo's Avatar
Registered User
 
Join Date: Apr 2002
Location: NW WA
Posts: 6,299
synthetic oils have been known to stop or greatly reduce oil leaks, for example I screwed up installing the rear main oil seal on my 616 and it leaked a little, after running Amsoil the leak almost stopped. I dont think it will raise 160 # compression to an acceptable level tho. I have freeded up sticking rings causing low compression using something like "Marvel Mystery Oil" and plenty of Itialian tuning up. Any story to go with the 160# reading, strange noises, smoke, over heating/out of oil event? Valves adjusted? Theres allot of good detectives around here
__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"
Reply With Quote
  #3  
Old 04-14-2009, 12:34 PM
ForcedInduction
Guest
 
Posts: n/a
What has been done to try and fix the car? Valve adjustment? Leakdown test? Italian tuneup? How much blowby does it have? Does it smoke blue?
Reply With Quote
  #4  
Old 04-14-2009, 12:53 PM
Registered User
 
Join Date: Mar 2008
Posts: 274
I did a valve adjustment a few thousand miles ago. Since I got new monarch nozzles haven't had much smoke at all, just a littl white/gray smoke if the car has been sitting awhile. Got the car a year ago and don't know much about it's history and I get the sense it sat awhile. It has a decent amount of blowby. It runs pretty well once warmed up but the engine seems jerky when first started. New motor mounts. I tend to drive it italian style much of the time.
__________________
1980 300D, 128K
Reply With Quote
  #5  
Old 04-14-2009, 01:03 PM
uberwgn's Avatar
Registered User
 
Join Date: Jul 2005
Location: New England
Posts: 979
While the high detergency of "synthetic" oils can help clean up ring lands, it's not going to relieve a severe case. It sounds like you may be at the point where a hammer and chisel are needed to clean out years of accumulation, Felix.

I suppose there's not much risk at trying. Your most economical choice will be Rotella's Syn 5W40. Many folks run this oil in their old 5cyl cars with good results. It's a modern all season/all climate oil.

Good luck.
__________________
1998 W210 diesel (wiped out by a texter)
Baum spring compressor "for rent"
Reply With Quote
  #6  
Old 04-14-2009, 01:06 PM
ForcedInduction
Guest
 
Posts: n/a
It's a modern all season/all climate dino oil made to act somewhat like synthetic.
Reply With Quote
  #7  
Old 04-14-2009, 01:07 PM
junqueyardjim's Avatar
Registered User
 
Join Date: Apr 2005
Location: Cicero, Hamilton County, Indiana about 30 miles north of downtown Indianapolis
Posts: 2,623
A little white smoke?

White in the tailpipe smoke indicates coolant in the combustion. Are you down in coolant once in a while. Also, with three good cylinders up front, then two adjoining cylinders at the back showing only a little more then 50% of the compression of the others, I think you might suspect a head gasket leak between those cylinders. I think you should pull the head and find out before you get too far from home.
__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!
Reply With Quote
  #8  
Old 04-14-2009, 01:11 PM
ForcedInduction
Guest
 
Posts: n/a
Quote:
Originally Posted by junqueyardjim View Post
White in the tailpipe smoke indicates coolant in the combustion.
As well as condensation from the air and normal cold combustion.
Reply With Quote
  #9  
Old 04-14-2009, 10:09 PM
Registered User
 
Join Date: Mar 2008
Posts: 274
my coolant level stays pretty solid, as does my oil. maybe i ought to test these numbers again to make sure, try synthetic and see if it does anything. i guess it's worth a shot. next oil change i'll do an analysis as well. don't want to turn this into an oil debate thread, but do you recommend rotella just because its cheaper or you think it's better? i read lots of recommendations for mobil delvac 1 for cleaning things out.
__________________
1980 300D, 128K
Reply With Quote
  #10  
Old 04-14-2009, 10:28 PM
Registered User
 
Join Date: Mar 2008
Posts: 274
another thought

not sure if this is relevant, but my car has been running somewhere around 173 F most of the winter, which seems little low.

__________________
1980 300D, 128K
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 07:55 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2022, 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