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 01-15-2008, 09:16 PM
Registered User
 
Join Date: Nov 2005
Location: Camden, Maine
Posts: 14
240D used to run, wont run now. What's up?

I thought I would begin this thread by describing the somewhat amusing circumstances which led to this car sitting dead in my driveway, but after reading back through it, it doesn't seem quite so amusing anymore, so maybe I'll just stick to what I think is useful information and see what you all think.

This is an '81 240D with 94K (49K on the current odometer, and an official sticker from the state of South Carolina saying when the first one broke.) However the current odometer broke 9 miles after I drove it away from SC, giving my cynical self reason to doubt the veracity of any odometer reading.

Only two owners, the first a surgeon who verified the mileage when the first odometer broke, and was replaced, the second, his mechanic, who I bought the car from.

I never had the compression checked before I bought it.

I live in Maine. I drove the car home from SC in April of 2007. On the 1500 mile trip home, it burned approx. a quart and a half of oil. It started well and ran well all summer long, whenever I used it, which was about once every week and a half. (I live on an island and drive a ferry during the summer, don't get to shore much during the busy season.)

The first time I tried to start the car after the weather got cold (40 deg?) it would not start. It eventually did after connecting to another car with jumpers. It was at this time that I accidentally discovered the air blowing out of the oil fill cap while the engine was running.

The car started well and ran well for a while again(don't remember temps.) Then when it got cold for real, it has not started since. Before even picking up the car in SC I ordered a block heater knowing I would need one here in Maine. Thinking that if the compression is suspect (the oil fill cap blowby?) a little warmth might make all the difference, I installed the block heater, (and ordered a compression gauge.) The block heater works really well, on the day I tried it, the block was warm, if not actually hot to the touch, certainly as warm as a summer day starting from cold. Nothing. Did not even think about starting. So next I checked the compression with the General tools gauge that I have read a lot of you guys talking about. I measured two cylinders through the glow plug holes before running out of light (working outside on a car in the winter in Maine sucks) but the two values were so depressing that I quit. Cylinder 1- 170psi Cylinder 4- 290psi. Both glow plugs worked though.

Next I decided to gap the valves and see if that changed anything. It was obvious as soon as I had the valve cover off that if the injectors were gone, gapping the valves would be much easier, so I took out all the injectors. They didn't look horrible to me, but there was a little carbon around the orifices on all of them. Some better, some worse. After the valve job, I checked the compression on all cylinders through the injector holes. Of course the values are on a cold engine since this one is pretty much perpetually cold these days. Cylinders 1,2, and 4 were 230 psi. Cylinder 3 was 210psi. Boogars.

Since I had the injectors out, I had them bench tested. They all popped off at around 1500 psi, and dribbled and squirted instead of misted. The guy who tested them took a new one off the shelf and showed me what it was supposed to look like, a fine mist that just hangs in the air. He said that all four of mine were bad enough to make the car hard or impossible to start, and run poorly.

Well that is good news I said. That might pretty much be the answer. Except when I told him about the compression values. His response was, "Oh, thats disappointing." Master of understatement this guy.

So the compression sucks, and the injectors are bad. So my questions are these:
1. How accurate is the General tools compression gauge?
2. With compression values this low, should the car have ever started or run well?
3. If I mimicked a hot summer day with the block heater, why didn't the car start, if it started all summer?
4. Are compression values comparable if done through different orifices? I can understand why cyl. 1 might have gone up after a valve job, but why did cyl. 4 go down, unless I made a mistake somehow.
5. Is it time to be contemplating giving up on this engine, vs. sinking more money and time into new injectors etc., etc... The shred of hope I am clinging to (in the face of those compression readings) is that the car ran and started well. If it doesn't now, then something must have changed. And if something changed, it can be unchanged. Compression values and injector function don't change overnight do they? I thought that problems there accumulated over long periods.

Thank you guys for reading as I babbled on about this one. Any ideas?

Reply With Quote
  #2  
Old 01-15-2008, 09:24 PM
Craig
Guest
 
Posts: n/a
Quick question: have you verified all 4 glow plugs yet? Two bad glow plugs will make these engines pretty hard to start even if everything else is OK.
Reply With Quote
  #3  
Old 01-15-2008, 09:26 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
There seems to be a general pattern of posts on this subject on this board. If a car has been sitting for a while and wont start, pull start it. I would not condemn the engine before attempting a number of pull starts. I'd put in replacement injectors, either new, rebuilt, or borrowed from another engine and pull start it on a warm day after I'd had the engine block heater plugged in overnight. Members have reported increases in compression after pull starting non-running vehicles that have sat for a while.
What's the story onthe glow plugs? You didn't mention whether you have tested them all.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #4  
Old 01-15-2008, 09:51 PM
Registered User
 
Join Date: Nov 2005
Location: Camden, Maine
Posts: 14
I have not checked all the glow plugs, just those first two. I did a continuity check, and checked the fuse, and the glow plug dash light functions, but I din not check the other two by pulling them and energizing.

What is the deal with pull starting? How do you do it with an automatic? I can track down the threads if it has been talked about before. Thanks.
Reply With Quote
  #5  
Old 01-15-2008, 09:55 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
Quote:
Originally Posted by erroneous monk View Post
What is the deal with pull starting? How do you do it with an automatic? I can track down the threads if it has been talked about before. Thanks.
It's something about the gods being pissed that we haven't driven our diesels.
These trannys have a pump that is activated by the driveshaft so you can turn the engine if you get going fast enough. Probably about 30mph as I recall. There are threads.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #6  
Old 01-15-2008, 10:10 PM
Registered User
 
Join Date: Nov 2005
Location: Camden, Maine
Posts: 14
Thanks, just looked up the pull start threads. How embarrassing that the info is actually in my owners manual. Not sure what that says about me. Any thoughts on whether those compression values on a cold engine are terminally low?
Reply With Quote
  #7  
Old 01-15-2008, 10:21 PM
Craig
Guest
 
Posts: n/a
Regarding the glow plugs, let me ask if you remember what type you have. In '81 there were two different types (series and parallel), do you remember which of these they looked like:

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ429Z1BSLLK&year=1981&make=MB&model=240-D-002&category=All&part=Glow+Plug&appEngines=_any
Reply With Quote
  #8  
Old 01-15-2008, 10:47 PM
Registered User
 
Join Date: Nov 2005
Location: Camden, Maine
Posts: 14
mine are the pencil type, no wire loop at the buisness end. Wired in parallel.
Reply With Quote
  #9  
Old 01-15-2008, 11:34 PM
Craig
Guest
 
Posts: n/a
Quote:
Originally Posted by erroneous monk View Post
mine are the pencil type, no wire loop at the buisness end. Wired in parallel.
OK, the quick way to test them is to measure the resistance across each one by unplugging the connector at the GP relay and using an ohm meter. The resistance values should all be around .8 ohms. Also, with the system connected, you should be measuring at least 11V at each of the GPs.
Reply With Quote
  #10  
Old 01-16-2008, 07:00 AM
Registered User
 
Join Date: Dec 2004
Location: Nashua, NH
Posts: 3,956
If you still have the injectors out how about running a compression check again, and do it both "dry" and "wet" to see if a little oil on the rings improves it any. I am suspicious of your compression gauge since you showed a decrease in compression after adjusting #4 valves so I would say run them all again and this time, if possible, have the gauge be closer to normal temperature (keep it in your coat to keep it warm). Maybe it has a leak when it gets cold...wouldn't be the first time something cold contracts enough to give a faulty reading.
__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz
Reply With Quote
  #11  
Old 01-16-2008, 07:19 AM
Registered User
 
Join Date: Sep 2007
Location: Redmond, WA
Posts: 622
Quote:
Originally Posted by erroneous monk View Post
I have not checked all the glow plugs, just those first two. I did a continuity check, and checked the fuse, and the glow plug dash light functions, but I din not check the other two by pulling them and energizing.

What is the deal with pull starting? How do you do it with an automatic? I can track down the threads if it has been talked about before. Thanks.
The owner's manual on my '83 240D Auto has the pull-start procedure written down and everything...it's a little bit complicated but not too bad. ~30 mph in neutral, then shift into drive. Or something like that.
__________________
1983 Mercedes-Benz 240D
Automatic, A/C, Power Sunroof, Power Right Side Mirror
231K Miles FOR SALE MAKE OFFER
Reply With Quote
  #12  
Old 01-16-2008, 07:25 AM
Admiral-Third World Fleet
 
Join Date: Feb 2002
Location: Central FL
Posts: 3,069
bad valve timing could be another possibility, but first make sure your glow plug system is up to snuff.
__________________
80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)
Reply With Quote
  #13  
Old 01-17-2008, 10:01 PM
Registered User
 
Join Date: Nov 2005
Location: Camden, Maine
Posts: 14
OK, I am on it, but can't work on the car until this weekend. You are right, I was making a bad assumption that the plugs were working simply because the two I pulled were OK. I had moved on mentally to the other obvious problems.

I will also re-do the compression test to see if the data is repeatable, and while I am at it, will do a wet test as well. How much oil and what weight should I squirt in the injector orifice before doing the compression? Thanks guys.
Reply With Quote
  #14  
Old 01-17-2008, 10:24 PM
speace's Avatar
Member
 
Join Date: Jan 2003
Location: Atlanta, GA
Posts: 371
Being a southern car, I have to ask if you have changed the oil after taking it home? ...and what viscosity of oil is now in the crankcase?

Years ago, my 240D and 300D took to refusing to start when it turned cold. It turned out my then mechanic had changed me to 20w50 oil! We went through so many things trying to figure out why they didn't want to start once the weather turned cool...

Yikes!
__________________
02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)
Reply With Quote
  #15  
Old 01-25-2008, 09:58 PM
Registered User
 
Join Date: Nov 2005
Location: Camden, Maine
Posts: 14
OK, I have checked the entire glow plug system- battery, relay, wires, and plugs and they all check out. All at .8 ohms on the nose, and also got battery voltage at the relay on all pins with the ignition in preheat mode. Rats, it would have been so easy if some of them were faulty. Next comes a retest of the compression, and I have just ordered new injectors. I don't know if that is all that is wrong here, but they are bad, so why not start there.

I changed the oil before I drove it up to 15W-40. Thanks

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 05:09 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