Well - it's been a while since my last posting on this subject because of shear and utter frustration. People tend to shy away painful subjects and I am no exception. The fact of the matter is that I've spent over $400 now with a local tech (timing chain, filters, diaphrams, etc...) with absolutely no results....that's the painful part.

I'm at this point wondering if the actual injector pump governing diaphram was really replaced to begin with. The thumb test gets the same results (change in RPM) and I found loose screws around the secondary vacuum pump. The injector pump section looks untouched. Hmmm.....Do the Secondary vac pump and the inj. pump have their own diaphrams or are they one in the same.....my invoice says "vac pump diaph replaced"......Hmmm....

HELP!!!!!!!!!

Todd

ps. If your just tuning in, please read the previous post entitled "Smokin' '76 240D".

I don't remember if I replied with the thumb treatment on this post but since you get the same results you have the same problem and unfortunately the vacuum pump pump diaphram is not the diaphram you need. The failure of that diaphram also causes smoking but it is unaffected by the thumb over the vent hole trick.

You have a problem with the injection pump diaphram. It is in the rear of the injection pump.

Thanks again for your help Steve. This still gives me hope to resolve this situation. At this point, I feel like I might just tinker and give it a shot myself. Is there a place I can order this part and a resource that might have some "destructions" on that repair? I have a good feeling on exactly where this part is on the pump too.

Thanks again,

Todd

Parts shop should be able to get the diaphram for you. The job is no big deal except for a couple item. First the screws that hold the cover on can be difficult. Onlt 4 if I remember correctly, but they are slotted screws not hex nuts and they can be difficult. The only other problem is that you have enough room for 1.5 hands and you need 3.0 hands to get the pieces inside the diaphram tube and assemble it on the end of the rack. Experience is a plus but other wise it just takes patience and fortitude; once everything is assembled around the rack pin your home free. Just pay close attention to the order of the springs and shims when you remove the old diaphram from the rack.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

I put in the part request yesterday after finding it on this site.....feel like an idiot for not seeing it earlier! LOL

Thanks for all the help.. I have a very exp. friend to help with the job as soon as the part arrives. I'll have to post the results again when complete.

Todd

No reply on the parts request yet....that sand must of shut down the laptop! Can anyone provide a part number for the Injector Pump Governing Diaphram for the 616 engine? (1976 240D)

I couldn't find your original post, but there are a few other 'tibdits' that can cause smoking - maybe you already know about these, maybe not

cracked brake booster diaphragm (the smoke is usually blue-ish, and accompanied by a loud droning noise)

broken/loose ball pin in the pre-chamber - common on engines that have backfired, or had injection pump /timing problems. Smokle is normally gray-ish, and is sometimes, but not always, accompanied by a pinging sound, almost like a detonation problem on a gas engine.

algae buildup if the vehicle has sat for any length of time - changing the filters wont fix it if there's algae in one or more of the injectors.(I've just had this problem on a rebuilt junkyard 240 - 3 of 4 injectors were fouled.)

bad hoses - if the soft return lines have a leak, there might be air in the fuel, or if the vacuum line from throttle plate to the IP has a leak, it'll have the same effect as a cacked IP diaphragm.(oh - and check that the vent cap is venting- if its sealed, the diaphragm in the IP wont function properly, either)

Ciao
G

The part# is 000 075 06 07 MB and 1 420 503 024 Bosch. Looks like list price is $53.00.

Good Luck

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Thanks for all your responses....Hopefully that part will come in soon.

Todd

Ahhhhhhhh...........

After the part arrived, I decided to take the plunge and DIM (Do It Myself). Steve was correct - you really need 2.5 hands for this operation (and I mean operation). There's really not that much room in that area. The problem was I had a serious lack of equipment that evening and had to use one hand to hold a light. The whole thing comes down to 4 slotted screws then one "e" clip. The position of the e clip is most precarious being located behind the diaphram inside the pump housing where it can easily be dropped causing another whole chain of events. Luckily, I happened to keep my grip on that one. On first inspection (before removing the diaphram), it appeared to be OK. When removed, a small slice was evident in the side I couldn't see. Ah.....the diagnosis was correct! Bad Diaphram! Of course, I had to wonder why it became damaged in the first place. I discovered a small engineering flaw when I went to reassemble the pump. When I went to place the large spring back in its position, I felt the sharp end of the metal on the spring. AHA! That must have cut the part! Well...maybe over 26 years of operation.....not a huge engineering flaw anyway......

I checked the other end of the spring and found it to be a little more smooth. This was the end that I put back in contact with the diaphram. After bolting the pump back together, the engine smoked for about 15 seconds and then ran very smooth with little or no smoke. There's now no smoke in between shifts nor when decelerating. Just a little puff on starts. Some smoke on heavy acceleration but it's black and after 349k on the od, I'd expect this to happen!

A very special thanks to Steve from Gainesville, FL for all his help and to others who have posted.

I just love a happy ending.........

Todd
76 240D (non-smoking section, please)
4 spd std shift and 350k after you read this.