76 240d IP diaphragm - PeachParts Mercedes-Benz Forum

sf240 · #1 08-17-2017, 11:21 AM

Hi, Ive been slowly bringing back to life a '76 240d. It's in pretty good shape with the exception of a fast idle and smoke. There is oil in the vacuum line that goes from the IP to the manifold so I removed the diaphragm cover and sure enough there's a hole in the diaphragm (plus a lot of fuel). I bought a new diaphragm and have done research on how to change it but it seems like the clip and pin I need to remove to get the old one out are about a 1/4" inside the IP. the instructions in the manual say to remove the "large governor cover". Is that the back end of the IP? There is a large what looks like an adjustment screw in the middle of this cover. I don't want to remove it and have a bunch of parts fall out.

Diesel911 · #2 08-17-2017, 12:57 PM

Quote:

Originally Posted by sf240

Hi, Ive been slowly bringing back to life a '76 240d. It's in pretty good shape with the exception of a fast idle and smoke. There is oil in the vacuum line that goes from the IP to the manifold so I removed the diaphragm cover and sure enough there's a hole in the diaphragm (plus a lot of fuel). I bought a new diaphragm and have done research on how to change it but it seems like the clip and pin I need to remove to get the old one out are about a 1/4" inside the IP. the instructions in the manual say to remove the "large governor cover". Is that the back end of the IP? There is a large what looks like an adjustment screw in the middle of this cover. I don't want to remove it and have a bunch of parts fall out.

There is springs and shims you need to keep track of where they came from.
There should be instructions and pictures:
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sf240 · #3 08-17-2017, 02:08 PM

Thanks for the link. I looked around and couldn't find anything listed as changing the diaphragm. There are some pics that show the diaphragm removed but not how it was done in this post: '75 240 D M-style IP Theory - Help!. I know there are shims and springs on the connection side of the diaphragm that I have to keep track of. The question I'm trying to answer is if the cover with the adjustment screw in it has to come off? I don't see any other way to access the clip and pin that hold the diaphragm in.

vstech · #4 08-18-2017, 11:25 AM

New members are not allowed to post with links in them.

Alec300SD · #5 08-18-2017, 12:54 PM

Here is the FSM procedure number 07.1 -215, hope it helps.

sf240 · #6 08-18-2017, 04:53 PM

Thanks for the link. That's the page I was referencing that says to remove the large governor cover to remove the diaphragm. I am assuming that is basically the back of the IP. I tried to get the slotted screws out but could only get one to budge. There's no room and I can't get any leverage. So I buttoned everything back up for now. It has a high idle so I just backed the idle screw out a bit and that made it shake like a demon. Brought the Idle back up a bit so at least it doesn't shake itself to death. I haven't checked to see what the motor mounts look like so that's something to add to the list.

Shortsguy1 · #7 08-18-2017, 07:04 PM

Here are two threads which will hopefully answer most of your questions.

White Smoke 220D - Mercedes-Benz Forum

Removing 220D Injection Pump Pneumatic Regulator Diaphragm...

I have not done the job you are working on, but if these threads don't answer all your questions, let me know and maybe we can figure it out together.

Diesel911 · #8 08-19-2017, 10:41 AM

Before you dissesemble you should test the little housng for vacuum leaks. Sometimes it is so worn that new O-rings won't fix it.

My recolection is that once you remove the larger governor back plate (the one the samll housing attaches to) and seperate the Diaphragm from both housings you can pull on the Diaphragm and that pulls the Rack to the rear and you can access the clip.

When the clip is off you slide the diaphragm off of the pin. Can't remember if that is left or right. When it comes off of the pin a piece in the center of the diaphragm is going to be loose and there is shims and spring behind it.

The little housing with the Adjusment screw inside should be removed and the O-rings replaces because it can be a source of vacuum leaks.

sf240 · #9 08-19-2017, 03:17 PM

Quote:

Originally Posted by Diesel911

Before you dissesemble you should test the little housng for vacuum leaks. Sometimes it is so worn that new O-rings won't fix it.

My recolection is that once you remove the larger governor back plate (the one the samll housing attaches to) and seperate the Diaphragm from both housings you can pull on the Diaphragm and that pulls the Rack to the rear and you can access the clip.

When the clip is off you slide the diaphragm off of the pin. Can't remember if that is left or right. When it comes off of the pin a piece in the center of the diaphragm is going to be loose and there is shims and spring behind it.

The little housing with the Adjusment screw inside should be removed and the O-rings replaces because it can be a source of vacuum leaks.

I think this is where I'm getting a little confused. What I removed is a unit of a small housing that has the engaging cam (15a/b) with lever and o-rings and the larger cover that holds the control spring (13) and washer (14) and connects to the vacuum line from the intake. At this point you have access to the diaphragm and can pull it back. This does indeed pull the rack to the rear but not enough to have a clear shot at the clip or pin. At this point I think I am at step 2 from the manual. Step 3 says to unscrew the large governor cover to gain access to the pin holding the diaphragm. I assume this is the back of the IP that holds the full stop screw (21). What I'm worried about is if the spring (20) for the full stop will be free and fall out. Also, would removing this cover drain the contents of the IP?

As far as checking the o-rings on the cam shaft they do leak a bit so I gooped them up with some grease to make a seal, at least enough to test, and it made no difference at all when I reassembled everything. When it was apart I could see what appears to be a tear at the bottom of the diaphragm and even though it's not very big I'm assuming that's the issue since there was a lot of oil/fuel in the area where the control spring is and also in the vacuum line.

Diesel911 · #10 08-19-2017, 06:44 PM

Quote:

Originally Posted by sf240

I think this is where I'm getting a little confused. What I removed is a unit of a small housing that has the engaging cam (15a/b) with lever and o-rings and the larger cover that holds the control spring (13) and washer (14) and connects to the vacuum line from the intake. At this point you have access to the diaphragm and can pull it back. This does indeed pull the rack to the rear but not enough to have a clear shot at the clip or pin. At this point I think I am at step 2 from the manual. Step 3 says to unscrew the large governor cover to gain access to the pin holding the diaphragm. I assume this is the back of the IP that holds the full stop screw (21). What I'm worried about is if the spring (20) for the full stop will be free and fall out. Also, would removing this cover drain the contents of the IP?

As far as checking the o-rings on the cam shaft they do leak a bit so I gooped them up with some grease to make a seal, at least enough to test, and it made no difference at all when I reassembled everything. When it was apart I could see what appears to be a tear at the bottom of the diaphragm and even though it's not very big I'm assuming that's the issue since there was a lot of oil/fuel in the area where the control spring is and also in the vacuum line.

I attached a pic

Here is the problem for me. I have not fooled with one of these since about 1975.
I think you can remove cover #1 in red and carefully pry out the aluminum rim of the diaphragm to gain access to the Pin and Clip.

If that is not so then you need to remove #2 in green.

I hope someone who has done it more recently will tell you more exactly what they did.

Diesel911 · #11 08-19-2017, 07:10 PM

more pics
In the firs pic you need to car3fully pry the diaphragm out.

The 2nd pic is not a Mercedes but you get the idea. Once the diaphragm is popped out you should be able to access the pin and if it has a clip the clip in manner similar to in the pic. Anyway that is what I remember\.

sf240 · #12 08-20-2017, 03:12 PM

That's pretty much where I stopped. I can pull the diaphragm back and it does pull the rack back but it doesn't come back as far as the second pic (Toyota pump?). It is still inside the IP by 1/4" to 5/16" and there isn't enough of a gap between the pulled back diaphragm and the opening to get any pliers in there (I'm thinking I'll need to during reassembly)

Diesel911 · #13 08-20-2017, 03:49 PM

Quote:

Originally Posted by sf240

That's pretty much where I stopped. I can pull the diaphragm back and it does pull the rack back but it doesn't come back as far as the second pic (Toyota pump?). It is still inside the IP by 1/4" to 5/16" and there isn't enough of a gap between the pulled back diaphragm and the opening to get any pliers in there (I'm thinking I'll need to during reassembly)

What type of clip is it you cannot reach?

Ya, it could be a Toyota pump and note that it has a cotter pin holidng the diaphram on the pin.
It was the only picture of it I could find quickly. If you want you can search some more. www.images.google.com and type in what you want to search for.

Since you need to replace the diaphragm any way if it was me I would just cut the dipahram away from the center and that would allow you more room to get the rest out. It would allow you to see more what you are going to need to do to get it back together.

sf240 · #14 08-20-2017, 05:25 PM

It looks like a C clip. I'm honestly more concerned with putting it back together, not sure how I'm going to get the clip in the right spot with the good diaphragm in place. I do have some curved pliers like that but I couldn't work them into the right spot. Maybe I'll have to look for more pliers. What a shame I'll have to buy more tools.

I did a search for photos and found a bunch of Toyota ones that's why I guessed that. It seems like the rack in those comes back a little further.

76w115 · #15 08-20-2017, 07:25 PM

If I remember correctly, I was able to get my clip out with needlenose pliers, and I believe I used a telescoping magnet tool to guide it into place on reassembly while pushing it into place with a small screwdriver.