75 240D injection pump oil consumption - Mercedes-Benz Forum

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 01-12-2010, 08:25 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Aug 2003
Posts: 9
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
75 240D injection pump oil consumption

I think I found out why my 1975 240D is loosing fuel prime but need an opinion from the veteran diesel owners out there.

I've had a devil of a time keeping fuel prime to the IP. Cleaned out all lines, tank strainer, etc. and just yesterday checked the oil level in the IP. It was very low or non existant. (bought this car used a few weeks ago and have had fuel starvation issues after the first week)

Filled it to the fill ring, started up fine, ran it around the block and it stalled again. Checked the IP oil level and it was gone!

What's going on???

Anyone have advice? Time for a new / rebuilt / used IP?

Thanks.
hjackson is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 01-14-2010, 05:46 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)
Use a Mity-vac to check your shut off diaphragm.
Mike D is offline  
post #3 of 11 (permalink) Old 01-14-2010, 01:25 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Aug 2003
Posts: 9
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
not sure how to test shut off diaphram

Quote:
Originally Posted by Mike D View Post
Use a Mity-vac to check your shut off diaphragm.
Sorry this is my first Mercedes diesel and I'm learning as I go along so I’m not sure how to do that. Is the vacuum line from the top of the IP to the intake manifold what I hook up a vacuum pump to (I assume a Mity-vac is a vacuum source) and what would I be looking for? Movement in the linkage, ability to hold vacuum?

-HJ
hjackson is offline  
post #4 of 11 (permalink) Old 01-14-2010, 04:38 PM
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)
Fill it to the fill ring?

There is a bleed screw on the side of the IP. Open that screw, fill oil from the top (red plug) and watch until oil (not diesel) escapes from the bleed screw. Only very little oil is needed, about 200 cubic centimeters, that is slightly less then 7 fluid ounces.

Change the oil every time you change the engine oil.

Check if your primer pump works by disconnecting the diesel line from the primer pump to the filter. If you use the starter it should pump diesel (you might need an assistant).

The vacuum of the governor is indeed something you should check, disconnect the vacuum hose from the intake manifold, put the pump in the stop position and hold your thumb on the open connection of the IP pump. Put the lever into the drive position and release your thumb. You should hear the pump going from stop to drive.

If it is your first Benz, read a bit how the vacuum-controlled governer of the IP works.
Govert70227 is offline  
post #5 of 11 (permalink) Old 01-14-2010, 10:14 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Aug 2003
Posts: 9
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Quote:
Originally Posted by Govert70227 View Post
Fill it to the fill ring?

There is a bleed screw on the side of the IP. Open that screw, fill oil from the top (red plug) and watch until oil (not diesel) escapes from the bleed screw. Only very little oil is needed, about 200 cubic centimeters, that is slightly less then 7 fluid ounces.

Change the oil every time you change the engine oil.

Check if your primer pump works by disconnecting the diesel line from the primer pump to the filter. If you use the starter it should pump diesel (you might need an assistant).

The vacuum of the governor is indeed something you should check, disconnect the vacuum hose from the intake manifold, put the pump in the stop position and hold your thumb on the open connection of the IP pump. Put the lever into the drive position and release your thumb. You should hear the pump going from stop to drive.

If it is your first Benz, read a bit how the vacuum-controlled governer of the IP works.
Ohhhh! Ok, I understand. I thought the oil should be all the way to the top of the fill plug. I guess the oil must have just pushed out of the vent filler plug and I thought it was being sucked through the diaphram. Live and learn. Thanks for your expert information. That helps a lot.

I purchased a CD based repair manual (along with the Chilton's I found in a local used bookstore) so I"ll study the information on the vacuum governor and check it out. In your example above, does one hear an audible "click" or "clunk" - I'm assuming these are well understood technical terms : -)

-HJ

Last edited by hjackson; 01-14-2010 at 10:16 PM.
hjackson is offline  
post #6 of 11 (permalink) Old 01-15-2010, 03:37 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)
In the picture below you can see the bleed screw. Loosen it, you cannot remove it altogether. Pour in the oil at the top, by unscrewing the red stop, until clean oil streams from the bleed screw



Here is another picture (of a slightly older MB diesel engine), but the bleed screw is number 3:



The pneumatic governor is a simple device, it works on vacuum created in the intake manifold. In the intake manifold there is a throttle, just like on gas engines. By pressing the accelerator you operate the throttle. Closed throttle = high vacuum, open throttle = low vacuum.

Below you can see a schematic picture of the pneumatic governor.



At number 12 the vacuum line is connected. When there is a high vacuum, the vacuum pulls the membrane (number 10) to the right, against the spring pressure. The membrane is connected to the controlling rod of the pump (number 8). When the controlling rod is pulled to the right, less diesel is injected, so the engine will slow down. Less vacuum, and the spring (number 13) will push the membrane to the left and more diesel is injected, causing the rpm to increase.

At idle and low rpm the notch 15 will be in position 15b, to prevent the engine from sawing (increase and decrease of rpms in a regular pattern). At higher rpms the notch will be in position 15a, and the rpm of the engine will solely be controlled by the vacuum and spring pressure.

If you check the airtightness of the governor, you should hear a click if you remove your thumb as the controlling rod moves to drive position. Below a picture where you can see how to check.



Common leakages occur around the axle of notch 15 or through the membrane.

The seal rings of notch 15 can be replaced or you can buy an expensive cover at your local MB or Bosch dealer. New seal rings must be available at a (Bosch) diesel service station.

Changing the membrane is a bit challenging, you need this set-up:





to check the play in the connection to the controlling rod.

Last edited by Govert70227; 05-26-2010 at 05:18 PM.
Govert70227 is offline  
post #7 of 11 (permalink) Old 01-16-2010, 09:12 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Aug 2003
Posts: 9
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
Thumbs up

Quote:
Originally Posted by Govert70227 View Post
In the picture below you can see the bleed screw. Loosen it, you cannot remove it altogether. Pour in the oil at the top, by unscrewing the red stop, until clean oil streams from the bleed screw



Here is another picture (of a slightly older MB diesel engine), but the bleed screw is number 3:



The pneumatic governor is a simple device, it works on vacuum created in the intake manifold. In the intake manifold there is a throttle, just like on gas engines. By pressing the accelerator you operate the throttle. Closed throttle = high vacuum, open throttle = low vacuum.

Below you can see a schematic picture of the pneumatic governor.



At number 12 the vacuum line is connected. When there is a high vacuum, the vacuum pulls the membrane (number 10) to the right, against the spring pressure. The membrane is connected to the controlling rod of the pump (number 8). When the controlling rod is pulled to the right, less diesel is injected, so the engine will slow down. Less vacuum, and the spring (number 13) will push the membrane to the left and more diesel is injected, causing the rpm to increase.

At idle and low rpm the notch 15 will be in position 15b, to prevent the engine from sawing (increase and decrease of rpms in a regular pattern). At higher rpms the notch will be in position 15a, and the rpm of the engine will solely be controlled by the vacuum and spring pressure.

If you check the airtightness of the governor, you should hear a click if you remove your thumb as the controlling rod moves to drive position. Below a picture where you can see how to check.



Common leakages occur around the axle of notch 15 or through the membrane.

The seal rings of notch 15 can be replaced or you can buy an expensive cover at your local MB or Bosch dealer. New seal rings must be available at a (Bosch) diesel service station.

Changing the membrane is a bit challenging, you need this set-up:





to check the play in the connection to the controlling rod.
Wow! This is an incredible amount of information!

Man, was I mistaken about the oil level in the injection pump. I certainly over filled it. I’m assuming that the excess just pushed it’s way through the filter cap or somehow was consumed by the engine.

I'll do the check on the vacuum line today. Your information about notch position 15b is illuminating also, because I've noticed that rpm oscillation shortly after I restart the motor after the fuel starvation event. It will even out after I pump the prime pump a while. So I suspect the seals may be worn?

Thank you for your valuable expertise.

-HJ
hjackson is offline  
post #8 of 11 (permalink) Old 01-18-2010, 03:39 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)
There is a vent pipe which throws out excess oil. Normally this can happen because diesel will leak past the pistons of the pump, slowly increasing the fluid level in the pump.

The fluctuating rpm is usually down to vacuum leakage. At idle the vacuum produced will fluctuate, but normally it will be enough to push the control rod against notch 15, but if there is a vacuum leakage, it will not be enough and the control rod will vary, causing the sawing idle. But if notch 15 is not adjusted properly, you might get the same problem. Adjusting the notch is done by the rod connected to it from the valve cover: disconnect the rod at the top (valve cover lever). It should go down a little bit, by about half the ball joint. If not, adjust the rod.

Below you see a picture of the inside of the back cover of the governor, with notch 15. The notch is operated by a rod from the valve cover.



A new cover from the dealer will cost about 140 euros (in Europe) as you can see below, I don't know the price in the US. The dealer will only sell this expensive complete cover.



The seal rings and axle can be renewed, using the parts below. I only have the name of the parts in German, but the Bosch part numbers should be enough. They might be difficult to obtain, so you probably need to call around to several (Bosch) diesel service stations.

Name of the part--------Bosch PART number--number required

VERSTELWELLE------------1 423 004 000----------1
SINTERBUCHSE------------1 900 301 012----------2
AUSGLEICHSCHEIBE--------1 420 100 012----------4
SCHENKELFEDER-----------1 414 651 060----------1
O-RING------------------1 900 210 105----------2
SICHERUNGSSCHEIBE-------2 916 080 910----------1
DICHTPLATTE-------------1 420 034 010----------1


A new membrane is slightly cheaper at the dealer, around 60 euro in Europe. A (Bosch) diesel service station can also sell this membrane, sometimes at a lower price.



Only replace/reconstitute the back cover and the membrane if there is a significant vacuum leak. Replacing the membrane is a bit tricky, removing and installing the lock ring and measuring and adjusting the play with a micrometer being the most difficult. The procedure should be described in the service manual.

The Service Manual is also the place where you can read about adjusting the rods, idle and maximum rpm.
Govert70227 is offline  
post #9 of 11 (permalink) Old 01-18-2010, 07:08 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Aug 2003
Posts: 9
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
performed tests - engine still starving from fuel.

Ok, I opened filled the IP oil sump using the level bolt as an overflow. Worked great.

Removed the vacuum line from the rear of the IP and had someone move the knob from the shut off position into the run position while holding my thumb over the orifice then quickly removing it. I did feel a suction and heard a “clunk” sound, as was suggested. I did this twice to make sure.

There is black rubber ring at the throttle position shaft that was loose and if it was supposed to be a seal, it was not sealing much of anything, but no fuel was leaking out either.

I bled the fuel system by the filter banjo bolt and also by the injector lines at the injectors. Started right up and ran it at fast idle for a long while (beyond warm-up) During that time I played with the butterfly at the manifold a bit and when I closed it the linkage followed a profile on the shaft plate and engine rpm’s went up. I don’t know what the correct engine response is supposed to be for this action.

Drove it around the block 8 times (about a mile) accelerating slowly and all ran well. Stepping it up a bit, I floored it from a stop and let it wind up to high rpms before the auto trans shifted. After driving a few blocks (about 1/4 mile) the engine began to lose power and sputter and I just limped home at idle speed before it quit just in front of my house (guess I was lucky at one thing)

Observing the prefilter, it seemed to be empty. I pumped the primer pump and it seemed to have filled the prefilter (kind of a milky white plastic so fuel is not easily visible) so at least I think that the primer pump sucks fuel from the tank.

My guess is that the delivery pump is not supplying proper volume of fuel to the IP at higher rpms which eventually starves the engine of fuel. Mercedes Source sells an electric fuel booster pump and I think that solution may make sense, but I have some concern. On the up side, it provides a presurized fuel flow from the tank, on the down side, it's an other component in the system that is not part of the original design and may influence the running of the engine (I understand newer diesels have an electric pump).

Any recomendations on this or other thoughts on what the problem is?

-HJ

Last edited by hjackson; 01-18-2010 at 07:40 PM.
hjackson is offline  
post #10 of 11 (permalink) Old 01-19-2010, 08:36 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)
If the prefilter runs dry during driving it can be caused by:
- not enough diesel in the tank
- rubber fuel lines at the tank are leaking, which causes air to be sucked into the fuel lines
- fuel lines between the tank and the pump are blocked
- primer pump is not functioning correctly

You can replace the primer pump, it is screwed to the main pump. I guess you can replace it with an electric one, if there is too much pressure, it will be pumped back to the tank. If you are concerned about originality, than buy a replacement primer pump. But first check the fuel lines running from the tank to the pump.

Checking the airtightness of the governor is done by first moving the pump into stop (you can remove the cable at the pump, see the picture "Bild 07-26/1" above, than you don't need an assistant), then putting your thumb on the hole of the vacuum hose, then releasing the lever into the normal position. If you release your thumb, then you should hear the click. If you do it several times, holding your thumb every time a little bit longer, you can establish how good it is holding vacuum.

By playing with the throttle on the manifold, you probably opened it, causing the vacuum to decrease and the rpms to increase. There are to throttles in the manifold, one for the vacuum, the other one to prevent to engine from running backwards. See the picture below.

Govert70227 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
    Testing injection pump on 240D frenchfry W123 E,CE,D,CD,TD,TE Class 16 11-18-2009 04:14 PM
    240d oil consumption dyonsl W123 E,CE,D,CD,TD,TE Class 2 09-18-2008 08:03 AM
    W123 Injection Pump Oil jhancoc W123 E,CE,D,CD,TD,TE Class 4 04-24-2007 11:12 PM
    What is normal oil consumption for 240d? jsl@gorge.net W123 E,CE,D,CD,TD,TE Class 3 06-13-2006 02:32 PM
    240D Injection Pump wdba123190 W123 E,CE,D,CD,TD,TE Class 1 08-21-2003 05:13 PM

    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