W115 240D governor diaphrahm replaced - now having issues with linkages/gear change.. - PeachParts Mercedes-Benz Forum

j-galap · #1 09-14-2020, 04:30 PM

Hi folks,

I got the governor diaphragm on the injection pump changed on my W115 240D a few days ago. It's solved a couple of major problems - the clouds of unburn fuel (grey smoke) and also sorted the idle issues with the car. Now the idle adjuster on the dash actually functions and idle at full operating temperature is now normal.

However, a couple of new issues have now surfaced!

Basically, the car doesn't want to change gear when pulling away. It doesn't make the car particularly driveable! I just shot a very short video to give a better impression of the problem:

https://youtu.be/b28oGYb-OwY

Also, I'm wondering if the way the linkages are setup, so here's a quick vid under the hood too:

https://youtu.be/dfOwEIpLWb4

Any thoughts? I took the car to a local Benz specialist for the work (which as great reviews) by the way!

Kind of confused as the car was very driveable before, despite all the smoke and idling issues, whereas now it should be better and is in fact less driveable

Edit:

For some reason, if I remove this linkage, the car drives better and is less hesitant under acceleration too:

Here's another video of the linkage thing:

https://youtu.be/dwg0YB3EJaw

Thanks!

Screwdriva · #2 09-14-2020, 05:20 PM

Two questions:

1) Have you got the part number for the diaphragm you changed? Was it a straightforward replacement or were other jobs done as well?

2) Have you changed the OFV spring and rebuilt your diesel lift pump? Did the specialist set the injection pump timing after replacing the diaphragm?

j-galap · #3 09-14-2020, 05:52 PM

Thanks for the reply.

1. I don't have the part number but I expect I can get it.

2. No, just the governor diaphragm was replaced. As far as I know the timing has not been altered.

Screwdriva · #4 09-14-2020, 06:20 PM

I'd like to cross check that part number. I'd also suggest checking injection pump timing as a next step. If the pump is set correctly then you know that the IP is operating correctly.

That said, your video highlights shift hesitation which is primarily vacuum driven.

tyl604 · #5 09-14-2020, 06:48 PM

Isn't that linkage from your accelerator train?

j-galap · #6 09-14-2020, 06:58 PM

It's the linkage that goes across the engine from the throttle body

resago2000 · #7 09-14-2020, 07:07 PM

IIRC, that rod connects to the idle damper on the IP via another turnbuckle
supposed to make idle smoother.
may be out of spec.IE. too long. it can be adjusted.

previous owner may have adjusted the rods to make it shift better with the overfeuling issue due to the bad diaphragm.
I don't think your trans uses vacuum, its all controlled by those rods and internal pressure.
just get those back into spec and you should be good.

resago2000 · #8 09-14-2020, 07:52 PM

this will help a little.
Mercedes-Benz /8 Limousine - Home > Technik > Dieselmotor einregulieren

j-galap · #9 09-15-2020, 10:27 AM

The push stop has also stopped functioning too. Could be related? Vacuum leak somewhere?

Edit: I can't even stop the engine running by putting it in gear, ignition off and holding the brake on (stalling it). The only way I can stop it running is to push the emergency stop on the throttle body itself

resago2000 · #10 09-15-2020, 11:05 AM

vacuum pod operates the stop, brown vacuum lines.
it pushes the stop toward the front of the car.
you can push it by hand to stop.
the other rod on the IP is idle damper.

can you take a picture of your IP?

j-galap · #11 09-15-2020, 01:05 PM

Here we go. Hope they're useful - wasn't sure what angles you needed!

High res ones are at this link

Thanks for your insight!

Mike D · #12 09-15-2020, 01:40 PM

On that style of injection pump the hard plastic line has nothing to do with engine shut down if properly installed. It is a governor. It regulates the amount of fuel entering the engine according to amount of vacuum created by a running engine.

There is no "brown" vacuum line used to shut down the engine. That feature didn't appear until 1976-ish model year on the OM616 and OM617 engines. The early OM61X engines used a manual shut down cable connected via the "gorilla knob".

resago2000 · #13 09-15-2020, 03:15 PM

I stand corrected.

j-galap · #14 09-15-2020, 03:54 PM

Thanks for the info. So, is it likely that due to the new governor diaphragm, the IP timing needs to be adjusted?

Mike D · #15 09-15-2020, 03:58 PM

NO! The diaphragm has NOTHING to do with injection pump timing. Timing the pump to the engine is a constant. The only thing which will change injection pump timing is chain stretch.