Removing diaphragm from IP governor housing
 

Hello again,

1974 240d.

I'm trying to diagnose a run away engine - idle problem.

I tested the diaphragm and realized no vacuum was present so I removed the housing to check the diaphragm.

Upon doing so, I noticed two small tears in the diaphragm.

Has anyone else has ventured into doing this. I did a search and came up with the same issue, but no one addressed how to specifically remove the diaphragm.

My problem is I am currently unable to get the diaphragm out of it's current position. Does anyone know if I had to remove the housing where the diaphragm sits or does it just pull out of it's current seated position?.

I attached a photo of the diaphragm with the housing removed and where I am at. This is a photo I removed from another thread related to my problem. The photo is nice and clear.

So looking at the photo do I have to remove the screws to release the diaphragm or does it just pull out, any insight?

Looking at a copy of the manual dealing with this subject, see address below...

http://mercedes.thatchermathias.com/w123CD2/Program/Engine/615/07-215.pdf

Reading bullets 2 and 3, it sort of indicates that you remove the first housing which I did and then remove the "larger housing."

Would that be the larger housing that is seen in the photo with the straight edge screws? I do not want to remove that larger/secondary housing and all of a sudden I have parts falling all over the place.

Thanks in advance,

Dwayne

Thanks,

Dwayne

My Memory is really bad on this. However, you will not have the Tool Shown in the Mercedes Manual so that is a guide.

What you want to do is dissemble it extremely carefully so that You see where the Shims and Springs go and replace those Springs and Shims back exactly where they came from.

Attached to the Diaphragm in the Center is a Tube with across drilled hole in in. What I can recall is there is Shims and a small spring inside of that Tube and the Rack or part of the Linkage to the Rack goes into the Cross Drilled Hole.
The parts I am speaking of I believe are in the circled area on the Diagram. But, like I said I am stretching My Memory on that.

Members have said it is cheaper to get the Diaphragm from the Dealer than Bosch.

I am trying to find the diagram from the Manual.

Looking at this diaphragm from Ebay, the shims and everything you speak of are behind the diaphragm, within the IP?

Mercedes Diesel Injection Pump Diaphragm 190D 200D 220D 240D 300D 406D 1963 79 | eBay

So I would have to remove an additional housing which keeps the diaphragm in place?

Looking at the first photo, that would entail removing the housing with the straight edge screws.

Sorry about being anal, just want to make sure I got it correct.

Thanks,

Dwayne

Carefully pull the diaghram out....it will not just fall out....once you pull it out, you will see the small pin that holds the shaft onto the rack....its small and a pita to remove and replace with out losing it into the IP.

Thanks Cooljay,
But does the diaphragm just come out or do I have to remove
the housing that is shown in the first photo/post.
Thanks,
Dwayne

It just pulls right out, if you grab the center part and pull it out....like the vacuum does....it just pops right out....it won't come off the rack with out removing the pin....also the diaghram is double layered...so the tares may not go all the way through.....did you confirm the clear plastic line that runs from the housing to the manifold is intact and not cracked?

Also check your coolant for oil....my friends car was doing this and eventually the head gasket blew...the coolant became oil...

Thanks so much Cooljjay,
Yes, the line is intact.
The car is not going anywhere soon, so no need to check the oil, but it was
Ok at the time.
The dealership did not have
the part so I ordered it and will await it's arrival.
Will post after the install.
Thanks again!

Er, mercedes may throw a cease and desist fit if they find their manual hosted online, they're funny that way. Of course, if the url is redacted and the procedure # is listed, people can find they're own way...

How about helping My memory out. I have not change out a Diaphragm since some time between 1975 and 1980.

When you pull out the Pin the part with the Red Dot on it comes out and there is a small Spring Inside and than there may or may not be some Shims at the bottom.

If there is Shims they need to be transferred to the New Diaphragm.

.

It's been a few years since I helped my friend do it....well pretty much watched him do it...I wasn't going to be blamed for losing the key in the IP :P

But I remember there was a spring in there, I can't say that I remembered there being shims in it....we were really worried doing it, because everyone said you need the special tools to shim the new diaghram....I believe it was a cotter key holding it on....I attempted to Google for a picture of it but had no luck...we just grabbed a used one and put it in.

The outer diaphragm ring sticks to the pump housing (it is a seal ring). The middle portion connects to the rack. You don't need to remove anything else, just disconnect the outer ring of the diaphragm.

There are shims and spring inside, so be careful when you pull the diaphragm out.

When you put in a new diaphragm, you need to measure the compensation path and set it correctly for the engine by removing or adding shims. The procedure is described in the FSM.

Most air leakages occur around the axle of the poppet cam, by the way.

@ moon161

MB USA has put the FSM for the W123, W124 and W201 online for free:
http://www.startekinfo.com/StarTek/doclist.jsp

Well, finally removed the damaged diaphragm and put the new one in.

Upon pulling the diaphragm it was attached to the rack as previously described by Moon.

I had to remove a c-clip which secured the diaphragm to the rack. That was a pain because of the restricted area and the fear of losing the c-clip into the IP. Also putting it back was no joy, again the fear of losing the clip into the IP.

Started the car up after I was sure it was all tight and everything was reconnected.

This was a very straight forward job to do, not to difficult at all.

Started right up and no more smoking or runaway engine. Felt real good about that.

Thanks to all that offered assistance!!

But the car still will not shut off properly. I have to manually go into the engine compartment and shut off the air supply to the engine after shutting the car via the key/ignition.

Any thoughts before I search and troubleshoot?

Thanks!!

Dwayne

Now you do realize to shut the engine down, you have to push the start/stop lever in....if that isn't the issue the problem will be the bushing on the injection pump....not sure where to get a new one....its easy to figure out, just follow the cable from the firewall to the injection pump...it looks like a throttle control cable..

Pay attention to your poppet valve in the governor
 

When you changed the diaphragm, did you test the poppet valve housing for vacuum leaks? I posted my work in the last two pages of this thread:

http://www.peachparts.com/shopforum/diesel-discussion/313588-injection-pump-maintenance.html

My poppet valve shaft was ground down by one of the bearings and that is where most of my vacuum leak is. I also have pinholes in the diaphragm as well and I'm not looking forward to setting that cotter pin back in but I'll get it done.

As for your shutoff, your start/stop armature to your pre-glow/pull starter knob may now be out of adjustment if the car won't shut off when you push it back in.

Phil Forrest

Thanks Phil and Cool, I'll check it out and no I did not check for leaks.

Dwayne