White Smoke 220D - Page 3 - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #21 of 53 (permalink) Old 01-23-2011, 08:10 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Jan 2011
Vehicle: 1969 220D
Location: California
Posts: 41
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Quote:
Originally Posted by Govert70227 View Post
It is not a spur gear, the pump is driven by a coupling sleeve over the splines.

There might be a rubber O ring on the axle of the injection pump that needs to be replaced and a new gasket is also advisable to prevent oil leakage.

The shaft of the pump needs to be free of oil and grease.

Take the pump out on 24 degrees BTDC and look if the marks on the pump line up when you take it out. That gives you an indication of whether timing of the pump was off the mark.



Also cover the open pipe connections of the pump with same plastic cling film (or special plastic caps) to prevent dirt entering the pump.
Thanks for the tips. I pulled the pump out and to my surprise the splines on the coupling bolted to the injection pump are internal, not external as your diagram and my book have it. I could not make out any similar markings or gap in the splines as your diagram shows. I simply put the pump back in but a little lower than I removed it. I then put things back and checked the onset of injection timing. I managed to get it right around 24 deg BTDC.
The bad news is that after putting everything back together it still smokes - a lot; marginally less than it did before and it does have more pep, but it still smokes. AGGRAVATION!!!!!!!!!!
Reflecting on the situation, I bet the fuel timing has been wrong for a long time. The same guy who elected not to refill the oil in the air filter probably was responsible for the bad timing. I keep "fixing things" that are wrong but are not the source of the problem.
GHewgill is offline  
Sponsored Links
Advertisement
 
post #22 of 53 (permalink) Old 01-23-2011, 10:21 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Jan 2011
Vehicle: 1969 220D
Location: California
Posts: 41
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Maybe I need to go back to thinking about the injectors. I don't have a neat hydraulic pump with a 20 bar gauge on it, so to test the injectors I simply attached them one at a time to the # 1 nozzle and connected a remote starting switch to the starter and observed the spray pattern, force of spray etc; all highly subjective I know, but I would recognize an odd spray pattern or a clogged injector or a leaky one. THey all delivered a small but forceful stream straight down. I caught the fluid in a dish and they all delivered enough fuel to aerosolize a little bit of diesel fuel as the stream struck the dish. I also tested three injectors I removed from a 240D at a junk yard in the same way. They behaved similarly. Am I kidding myself here? Should I buy new injectors or get a hydraulic tester? Any other thoughts of what could be at fault here that is slowly getting worse all the time? After each service I've performed I get marginal improvement but the trajectory of performance is downward.
Thanks,
Greg
GHewgill is offline  
post #23 of 53 (permalink) Old 01-24-2011, 02:27 AM
BenzWorld Elite
 
Govert70227's Avatar
 
Date registered: Oct 2009
Vehicle: 2000 VW Golf Variant
Location: Leiden, Netherlands
Posts: 2,952
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
Quote:
Originally Posted by GHewgill View Post
Thanks for the tips. I pulled the pump out and to my surprise the splines on the coupling bolted to the injection pump are internal, not external as your diagram and my book have it. I could not make out any similar markings or gap in the splines as your diagram shows. I simply put the pump back in but a little lower than I removed it. I then put things back and checked the onset of injection timing. I managed to get it right around 24 deg BTDC.
There is a coupling sleeve over the splines, that connects the pump with the intermediate shaft. The sleeve can be pulled off. The sleeve has the splines on the inside of course.

Quote:
Originally Posted by GHewgill View Post
Maybe I need to go back to thinking about the injectors. I don't have a neat hydraulic pump with a 20 bar gauge on it, so to test the injectors I simply attached them one at a time to the # 1 nozzle and connected a remote starting switch to the starter and observed the spray pattern, force of spray etc; all highly subjective I know, but I would recognize an odd spray pattern or a clogged injector or a leaky one. THey all delivered a small but forceful stream straight down. I caught the fluid in a dish and they all delivered enough fuel to aerosolize a little bit of diesel fuel as the stream struck the dish. I also tested three injectors I removed from a 240D at a junk yard in the same way. They behaved similarly. Am I kidding myself here? Should I buy new injectors or get a hydraulic tester? Any other thoughts of what could be at fault here that is slowly getting worse all the time? After each service I've performed I get marginal improvement but the trajectory of performance is downward.
Thanks,
Greg
I hope you mean a 200 bar gauge, because at 20 bar the injectors should not be opening. Normal opening pressure is about 115 bar, lower limit is 100 bar. The spray pattern should be a small closed cone, not a single stream, although some injectors have a pre-injection stream. The only way to properly test the injectors is with a hand pump. There are two ways: either make or buy a hand pump and test the injectors yourself. With the aid of the hand pump you can also replace the nozzles in the injectors, although you need shims to adjust the opening pressure of the injectors. The other way is bring the injectors to a diesel workshop, have them test and replace (if necessary) the nozzles. It is about an hour's work for them.

You haven't addressed the leak of the pneumatic governor. If the car is idling normally (700-800 rpm) than the throttle was screwed back to produce enough vacuum so that the engine doesn't idle too high. That will increase smoke (and fuel consumption).

Smoke out of diesel engines is (if it isn't coolant because of a leaky head gasket) is mostly unburnt diesel. Diesel will not burn because of lack of compression, not enough air, too much diesel injected or injected at the wrong time.

I would probably do a compression test and a compression leak down test to see whether the pistons, cylinders and valves are working properly. It could be that the engine is worn out. The engine has to be warm for these tests.

Diagnosing a problem isn't always easy, certainly not on an old car with neglected maintenance, but take it one step at the time, easiest/cheapest things first, more complicated/expensive things second.
Govert70227 is offline  
post #24 of 53 (permalink) Old 01-24-2011, 10:23 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Jan 2011
Vehicle: 1969 220D
Location: California
Posts: 41
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Smile

Yes, I meant 200 bar not 20. An order of magnitude issue, probably because I really think in pounds per square inch, not bar or Pascal.

That makes sense about the splines. Silly me, I read your post when you mentioned the collar, but I was still expecting to see a male and female part rather than two external splines with a collar joining them. Oh well, despite my misapprehesion this adjustment seemed to go OK.

I will fiddle with the idle at lunch hour. Some weeks ago when this problem began to appear I had raised the idle since I found it smoked less at a higher idle, but had rather optamistically turned it back this weekend thinking that I wanted to reset everything to "normal."

Yes, there is the leaky pneumatic governor situation, but I found that when I put the viscous oil on the poppet shaft it did help it hold vacuum, yet made no perceptible difference in how the engine ran. This inclined me to believe that this is really not a problem, even if it could be better.

The flow from the injectors is conical but very tight, to the point that it appears to be a straight stream, isn't that right? This is how it appears to me on the video I've seen anyway (and how it looked when I connected the injectors). If it was indeed coming out as a solid stream I can't imagine that it would be straight down; wouldn't it be directed to one side of the other since the nozzle opening creates this cone when the tip rises out of the whole in the nozzle when the pre-set pressure has been achieved? If it were a solid stream that would mean it was only coming out on one side of the nozzle or the other.

Yes, I do realize that I'm rather handicapped because I don't have proper test equipment, so I'm relying on observation and inference (and I'm too cheap to take it in to the shop .

Thanks again for the advice; I will persevere.
Greg
GHewgill is offline  
post #25 of 53 (permalink) Old 01-25-2011, 05:12 AM
BenzWorld Veteran
 
Date registered: Aug 2009
Vehicle: '72 250C, '74 280C, '85 500SEL, '81 300CD.
Location: Tucson, Az.
Posts: 679
Mentioned: 3 Post(s)
Quoted: 51 Post(s)
You are shooting in the dark. Do the compression test before you go any further. Anything below 300 p.s.i. is suspect.
Mike D is online now  
post #26 of 53 (permalink) Old 01-25-2011, 10:16 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Jan 2011
Vehicle: 1969 220D
Location: California
Posts: 41
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Quote:
Originally Posted by Mike D View Post
You are shooting in the dark. Do the compression test before you go any further. Anything below 300 p.s.i. is suspect.
Thanks Mike, yes I was thinking last night that I need to get the tool (I have a compression tester for gasoline engines but doesn't fit diesels) and do that to rule it out. Low compression was not my first thoguht because it starts so easily, but there's nothing like some hard data.
Greg
GHewgill is offline  
post #27 of 53 (permalink) Old 01-25-2011, 10:24 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Jan 2011
Vehicle: 1969 220D
Location: California
Posts: 41
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Quote:
Originally Posted by GHewgill View Post
Thanks Mike, yes I was thinking last night that I need to get the tool (I have a compression tester for gasoline engines but doesn't fit diesels) and do that to rule it out. Low compression was not my first thoguht because it starts so easily, but there's nothing like some hard data.
Greg
Hey, Im quoting myself! OK, bad joke. I bought the compression tester and did the test. All four cylinders are at 360 psig (26 bar).

Further suggestions?
Thanks,
Greg
GHewgill is offline  
post #28 of 53 (permalink) Old 01-26-2011, 06:13 AM
BenzWorld Veteran
 
Date registered: Aug 2009
Vehicle: '72 250C, '74 280C, '85 500SEL, '81 300CD.
Location: Tucson, Az.
Posts: 679
Mentioned: 3 Post(s)
Quoted: 51 Post(s)
Ok. Now you know; compression is good, valves are not burnt, head gasket is not blown and it is not an internal engine mechanical problem.

Next step. What did you determine the pump timing to be? You must check the pump by either drip or rise method at the #1 compression stroke. I'm guessing you are but make sure you are on the compression cycle. Pull the valve cover and check. (turn the crank until the #1 intake valve opens then continue turning to 24-30 degrees BTDC).
Mike D is online now  
post #29 of 53 (permalink) Old 01-26-2011, 08:27 AM
BenzWorld Elite
 
Govert70227's Avatar
 
Date registered: Oct 2009
Vehicle: 2000 VW Golf Variant
Location: Leiden, Netherlands
Posts: 2,952
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
Quote:
Originally Posted by GHewgill View Post
I will fiddle with the idle at lunch hour. Some weeks ago when this problem began to appear I had raised the idle since I found it smoked less at a higher idle, but had rather optamistically turned it back this weekend thinking that I wanted to reset everything to "normal."

Yes, there is the leaky pneumatic governor situation, but I found that when I put the viscous oil on the poppet shaft it did help it hold vacuum, yet made no perceptible difference in how the engine ran. This inclined me to believe that this is really not a problem, even if it could be better.

You've established with a vacuum gauge that the governor doesn't hold vacuum, that is a problem. That will cause smoke and diesel not being burnt because of lack of air.

What happens is the following. Under normal conditions you have to open the air valve half way and than the engine runs at let's say 3000 rpm. If the governor cannot hold vacuum, you only need to open the air valve for a little bit for the engine to run at 3000 rpm. The problem is that the air valve doesn't let enough air through to the cylinders, but the amount of diesel injected is still the same.

Good to hear that the compression is in order. Did you check with the air valve completely open?

If you have checked through the injector openings, don't forget to use new heat shields under the injectors.
Govert70227 is offline  
post #30 of 53 (permalink) Old 01-26-2011, 10:06 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Jan 2011
Vehicle: 1969 220D
Location: California
Posts: 41
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Quote:
Originally Posted by Govert70227 View Post
You've established with a vacuum gauge that the governor doesn't hold vacuum, that is a problem. That will cause smoke and diesel not being burnt because of lack of air.

What happens is the following. Under normal conditions you have to open the air valve half way and than the engine runs at let's say 3000 rpm. If the governor cannot hold vacuum, you only need to open the air valve for a little bit for the engine to run at 3000 rpm. The problem is that the air valve doesn't let enough air through to the cylinders, but the amount of diesel injected is still the same.

Good to hear that the compression is in order. Did you check with the air valve completely open?

If you have checked through the injector openings, don't forget to use new heat shields under the injectors.
Thanks for the post Govert. OK, I'll see if I can get the cover part with the poppet valve and all the seals. I acknowledge that it leaks and therefore isn't what it should be, but I'm a little skeptical about that being the source of the problem for a couple of reasons: 1) when I put the viscous oil on the poppet shaft it definitely holds vacuum better, but the engine runs the same - no change in idle and no reduction in smoke, 2) My experience with "adjusting the vacuum" in an attempt to determine whether it is over-fueling or not. Let me explain. I brought a small lab vacuum pump from my work (I'm a chemist) and connected it to the pneumatic governor port on the injection pump. My thinking was to "dial-in" the right vacuum for a reasonable idle and then open the air valve on the throttle body and see if supplying more air to the engine would reduce smoke. Well, my experiment wasn't very successful. Even though this vacuum pump has an air bleed valve, I found it very difficult, actually impossible, to get the engine to run at idle speed. It would either race or stall. Well, race is an exageration, but way above idle anyway. If I increased the vacuum marginally from a normal running speed (I'm guessing around 3,000 RPM, but I have no tachometer so it's only a guess), it would slowly slow in speed and then stall. I'm still not sure why this should be, but perhaps the system requires the natural feed-back that occurs between the engine vacuum and the delivery of fuel. Maybe de-coupling these two isn't possible. So, even though my "experiment" wasn't successful, I think I learned a couple of things. One is that the engine speed is determined by the injection pump - it will pull more air through the throttle body even if it is restricted. When it did this there seemed to be less smoke, not more, even though this is certainly an over-fueling situation. If the leaking seals on the pneumatic governor were consequential, why isn't the idle unacceptably high (as in my vacuum pump situation)?

Perhaps I'm mudying the waters here, and your explanation of the fuel/air ratio makes perfect sense, but then I go back to my point 1) above. Barring some revelation I will replace the part, but it seems like I might be fixing yet another thing that really won't solve the problem.
Thanks again,
Greg
GHewgill is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > General Mercedes-Benz Forums > Vintage Mercedes-Benz

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
     
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode



    Similar Threads
    Topic Author Forum Replies Last Post
    White Smoke Sondrusen General Mercedes-Benz 5 11-10-2010 10:03 AM
    white smoke ready6six W126 S,SE,SEC,SEL,SD,SDL Class 3 09-21-2010 03:07 PM
    white smoke, I need your help please!! 560 lover W126 S,SE,SEC,SEL,SD,SDL Class 42 07-06-2010 02:09 PM
    White Smoke bloodpirate W124 E,CE,D,TD Class 10 08-04-2009 01:11 AM
    White Smoke SParkyMerc W126 S,SE,SEC,SEL,SD,SDL Class 2 05-12-2006 02:10 AM

    Posting Rules  
    You may post new threads
    You may 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 Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On

     

    Title goes here

    close
    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome