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 10-18-2004, 01:08 PM
michael cole's Avatar
Registered User
 
Join Date: Apr 2002
Location: waterloo ontario
Posts: 730
Smile new to me 300tdt

love this car.but a few issues unfortunately.the most pressing being cold starts.all glow plugs are working and resistance is on spec but its clear one cylinder is misfiring with a thud every few seconds.after warmup it runs and pulls smooth with lots of power. however at idle i do see a little white smoke of the unburned fuel variety.at least thats what my nose tells me.using the glow plugs as pyrometers hooked to my ohmeter i observe cylinder#5 is burning cooler than the others indicated by higher resistance than average.i have a bosch pop tester and utilized this to check injection pressure and spray pattern which is good on all injectors.i pulled the intake manifold and checked all the intake ports which like the manifold were covered in a thick layer of black goo which i proceeded to remove with varsol.reassembled and restarted with no positive effect.where do i go next??does this look like the symptoms of a valve ,ring or sleeve problem?

Reply With Quote
  #2  
Old 10-18-2004, 01:51 PM
JamesStein's Avatar
Registered User
 
Join Date: Apr 2004
Location: Tallahassee, FL
Posts: 586
Have you adjusted the valves?
__________________
'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.
Reply With Quote
  #3  
Old 10-18-2004, 01:55 PM
michael cole's Avatar
Registered User
 
Join Date: Apr 2002
Location: waterloo ontario
Posts: 730
ooops!forgot to mention this is an 87 with 603 engine.
Reply With Quote
  #4  
Old 10-18-2004, 09:19 PM
Registered User
 
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
White smoke is a sign of low compression OR a bad head gasket.

Does coolant slowly disappear from the reservoir? If so, expecially if you also have pressure in the cooling system when it's cold (before starting), you have a cracked head and will need to replace it before it hydrolocks and you bend some rods.

If not, do a compression check and leakdown check -- this engine will use oil if you have bad cylinders, so if you don't have oil consumption problems, it's likely a valve problem if you have low compression.

Dead hydraulic tappets can give you low compression, too.

If you have serious injector knock on that cylinder, you may also have a leaking pressure valve holder in the IP.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
Reply With Quote
  #5  
Old 10-19-2004, 08:51 AM
michael cole's Avatar
Registered User
 
Join Date: Apr 2002
Location: waterloo ontario
Posts: 730
no coolant loss or oil consumption so far in 2000km so i doubt head problems.i will perform a compression test asap and leakdown as well.how can i check for bad delivery valve on the IP?
Reply With Quote
  #6  
Old 10-19-2004, 07:18 PM
Registered User
 
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Micheal:

A bad pressure valve seal will cause late injection and noticable to terrible injector knock on that cylinder, but show normal fuel delivery with the cap nut loose. You will also have a partial missfire on that cylinder and rough idle/poor performance under 1500 rpm. Above that, normal operation.

The compression may be low on that cylinder due to carboned up rings too -- this goes away when you fix the seal.

Complete diagnosis is to re-torque the pressure valve holder on the IP (requires a special splined socket). If the problem goes away, it was the seal.

A leakdown test will tell you if you have a burned valve causing low compression -- not common, but possible.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
Reply With Quote
  #7  
Old 10-20-2004, 10:40 AM
michael cole's Avatar
Registered User
 
Join Date: Apr 2002
Location: waterloo ontario
Posts: 730
psfred thanks for your reply.the symptoms you mention sound exactly like what is happening.is there a seal inside that can replaced or is it strictly a matter of re torqing?
Reply With Quote
  #8  
Old 10-20-2004, 06:48 PM
Registered User
 
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
There is a copper seal sitting on top of the pressure valve body, they are cheap and once you are in there that far, it's kinda silly not to replace them.

However, this is usually a problem on a car where the o-rings on the pressure valve holders have been replaced to fix the fuel leak when they go bad. If you have fuel residue on top of the IP, chances are you need to replace them since the old ones didn't seal.

I'd replace the rubber o-rings too -- total cost when I did this three years ago was less than $9.00. Cured mine.

Peter
__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
Reply With Quote
  #9  
Old 10-26-2004, 02:40 PM
michael cole's Avatar
Registered User
 
Join Date: Apr 2002
Location: waterloo ontario
Posts: 730
psfred do you happen to know the torque value for the delivery valves?i could not find this in any docs i have.i have ordered the special socket and seals
Reply With Quote
  #10  
Old 10-26-2004, 08:02 PM
Registered User
 
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
24 ft/lbs, loosen, 25 ft/lbs, loosen, tighten to 30 ft/lbs.

It's in the engine manual, the same for all injection pumps.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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 04:31 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, 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