Diesel Discussions Only diesel topics should be posted here.

diaphram replacement woes om615

Old 12-26-2014, 09:10 AM
Junior Member
Thread Starter
Join Date: Dec 2014
Posts: 2
Default diaphram replacement woes om615

My MB manual states diaphragms should be replaced with corresponding spring. I purchased a diaphragm from the Medford MB dealer but no spring was included - I count 3 different springs. Which one are they referring to?. After inspecting the new part was identical, I switched it out for the old, carefully installing the old parts. The engine runs poorly, issuing light smoke and the governor is hunting like I was blipping the throttle.
I have pulled the pump four times since, using the drip method and carefully aligning 26 btc, checking the pump gear scribe, compression check (all 300 lbs +) adjusted the valves, replaced injectors and it still runs terrible.
Because of the governor hunting, I suspect there is too much slack between the push rod and the diaphragm allowing it to pump with the vacume. The manual states the push rod should just touch the diaphragm and adjustment can be made via the nut on the piston in the governor chamber.
I'm assuming this is when the diaphragm is in it's rearward (stop position) but I don't know. Tough question but if anyone has a clue to offer, I would certainly appreciate it - my hands look like I'm wearing black gloves. Thanks!
Attached Thumbnails diaphram replacement woes om615-004-800x600-.jpg   diaphram replacement woes om615-005-640x480-.jpg   diaphram replacement woes om615-003-640x480-.jpg  
Old 01-01-2015, 09:49 PM
Senior Member
Join Date: Jan 2008
Posts: 553

From what I have read most People have been able to change only the Diaphragm with no issues.

What is missing is if you tested to see if there is a vacuum leak in the newly installed Diaphragm or the back Housing with the Lever on it.

It is common for the Housing to leak in the Lever Shaft area.

In the Manual there is instructions on how to do the test if you have the complete manual.
Old 01-04-2015, 09:30 AM
Junior Member
Thread Starter
Join Date: Dec 2014
Posts: 2

Thanks, Forced induction,
Apparently, I threw out the two compensating shims along with the old diaphgram - they must have been stuck. I'll crank it up again when I get enough courage.
Practice does make it a much quicker job compared to the first in & out of the pump and related gear. Thanks again for the post..
Related Topics
Thread Starter
Last Post
Mercedes C Class
04-16-2012 03:48 PM
Mercedes E Class
09-06-2005 05:13 PM
General Tech
06-21-2005 06:51 PM
Mercedes C Class
06-16-2005 02:33 PM
Mercedes E Class
04-08-2005 07:29 PM

Thread Tools
Search this Thread
Quick Reply: diaphram replacement woes om615

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.