Delivery Valve Seal - Tricky

[Number_Cruncher]

I know there are one or two people about to replace their delivery valve seals on their OM606 engines.

I would like to sound a note of caution - this is a job that can easily go wrong. The latest to be caught out, albeit with a 603, is here;

http://www.mercedesshop.com/shopforum/showthread.php?t=228781

I suspect the the lapped joint between the top of the plunger barrel and the body of the delivery valve isn't sealing, and the delivery valve, therefore, never opens.

In short, I'm saying tread very carefully.

 

[compress ignite]

DV O-rings and seal

7K and 7g MUST maintain their respective relationships to each other
(I.E. No Rotation in either direction)

AND 7g MUST maintain it's original relationship with the Delivery Valve Holder
in which it sits.

These parts have established a "Lapped" relationship to each other,and in the
case of 7g ALSO with the underlying holder.

Fanatically Scrupulous Cleanliness is a must and will be rewarded !

(I.E. Before you tear into this task,the outside of your IP should be fit for
Operating Room/Surgical use.)

(Instructions on the pictogram are for 602.XXX engine yours may differ)

 

[Dieselman]

I suspect what's happening is that people aren't aligning the componets up properly on reassembly, so trapping the valve insert or spring.
Last delivery valve I had to do was on the side of the road due to leaking diesel.
Valve out, reseal, valve back in carefully...job done.

Admittedly this wasn't on a Bosch in line pump but the same principle applies.

 

[SilverSaloon]

thanks - will take a good read through that post.

havnt done this job yet but as i can tell from posts on here and the how to; if you only remove what you need to remove to change the o-ring and copper washer and dont dig deeper then not that much gets disturbed?

Its indeed scary stuff, but i dont think i have a choice really - i'm leaking quite a bit of fuel so got to have a go at fixing it.

 

[a111r]

Delivery valve issues

Interesting. Does anyone know if miss positioning one or more '7g's during O ring replacement could cause an over-fuelling on idle symptom, i.e. too smokey? Any other suggestions that could are warmly welcomed ! I can go into more detail if required....
Thanks, Andy

 

[Smiley]

Andy, You may have an air leak in the fuel lines causing the smoke on idle.

 

[a111r]

Cheers Smiley, that's really helpful. I've been going off into a sort off 'tailspin', round and round the same issues related to what I've changed or tweaked. Perhaps I need to do the shut off o ring? My other car's quickly went pear shaped (or rather rectangle shaped...) after svo experiments, stranding the wife. Contrary to post I've seen (mercedessource, e300d?) i found the 2 screws fairly accessable and not siezed, so a ten minute job. Think I did most of the pipe o rings.
cheers
Andy

 

[Dieselman]

Interesting. Does anyone know if miss positioning one or more '7g's during O ring replacement could cause an over-fuelling on idle symptom, i.e. too smokey?

Very unlikely.
The delivery valve serves two purposes, the first is to cause sudden depletion of pressure as the IP reduces pressure, which causes the injector to snap shut ceasing delivery suddenly, the other task is to act as a one way valve so the IP element can suck fuel in from the supply rail.

Smoke indicates a dribbling injector at small openings. Run the engine on neat injector cleaner by connecting a bottle upto teh filter and the return back into the bottle.

It's also worth checking the EGR valve isn't stuck open.

 

[a111r]

Cheers, i'll try the EGR move as the injectors have been stripped and fitted with new nozzles, so a cleaner, unless acting on other parts, won't be of use, I would think.
BTW, do you know if the system Bosch use for the 'part numbers' of nozzles has any empirical basis, i.e. can one decode the properties or make comparissons?

 

[compress ignite]

delete

Delete

 

[Number_Cruncher]

Here's another with a possibly damaged injector pump;

http://www.mercedesshop.com/shopforum/showthread.php?t=237601

Just to clarify, I'm not saying that this job will damage your injector pump, people have done the job successfully, just that in DIY hands, there seems to be a high attrition rate.

 

[SilverSaloon]

Here's another with a possibly damaged injector pump;

http://www.mercedesshop.com/shopforum/showthread.php?t=237601

Just to clarify, I'm not saying that this job will damage your injector pump, people have done the job successfully, just that in DIY hands, there seems to be a high attrition rate.

I did this job a couple of months back. Only advice i can give is dont touch anything you dont need to and there shouldnt be a problem as far as i can see. Clean up the area before undoing anything. Its just a spring, and copper washer in there to remove. Dont touch anything below that and remove these bits very carefully with a small minature screwdriver. Make sure no grime gets in when you unscrew the valve and clean again carefully when its removed. I am purly a DIY guy and know very little about cars and only do stuff based on "winging it" and internet "how tos"

The guy in the link used a magnet and removed more than necessary - bad idea to use a magnet. Be careful and remove only what you need to.

my car runs fine since and the leak is sorted.

 

[Dieselman]

Here's another with a possibly damaged injector pump;

He's got an air leak causing fuel starvation.