Here ya go:

Most fuel leaks on the OM606 engine happen around the fuel pump, specifically the plastic fuel lines between the pump and the two fuel filters. These, while a bit inaccessible, are generally a quick and easy job to replace.

Tools:

Mercedes splined tool part no - 617 589 01 09 00
6 x copper seal (7f)
6 x o-ring (7h)
Sockets, torque wrench, torx bits, extensions, etc

Delivery valve schematic:

http://homepage.ntlworld.com/tom.jeffs4/car%20stuff/merc%20tech/diesel%20delivery%20reseal-1-1.pdf

The fuel leak we fixed today was on the other side of the pump - the injector side. This is where fuel is pumped out at high pressure, down hard metal lines, into the injectors, and thus into the engine. The leak was at the 6 valves on top of the pump (1 valve for each cylinder). There are 6 o-rings (these are the source of the leaks) and 6 crush washers to replace. To access these valves, the intake manifold must be removed, as well as the washer bottle and all 6 injector lines. Its probably not a job for an amateur DIYer like myself, which is why I was very glad to have my mate with me, who is much more experienced in these matters than I am. Its a good idea to have 2 people on this job anyway, since a spare pair of hands is invaluable for catching hold of loose springs, holding clamps, etc.

1) Remove washer bottle

1 bolt holds my bottle in place. Remove that, and pull the bottle to the front of the car - it will un-clip itself from a small bracket. Remove any connectors on the top, and put it out of harm's way (I left it resting on the +ve battery terminal).

2) Remove intake manifold.

Full instructions can be found in the EGR cleaning thread here (http://forums.mercedesclub.org.uk/showthread.php?t=25922). Essentially theres 1 bolt accessed from above, this un-clamps the small pipe that enters the EGR valve to the back of the engine. Another bolt below (Allen IIRC) holds 2 aircon pipes to a clamp, said clamp also is bolted onto the chassis. There are 12 torx bolts on the top of the manifold screwed into the head.



Once these are all removed, the intake manifold should come completely clear.

3) Remove injector lines

The 6 injector lines must be removed from the pump, and the injectors. This is easy enough, just a normal spanner can be used. Unscrew each line, its easier to start with line 6 (rearmost cylinder) and work down to line 1. As you unscrew each line, take care not to mix them up.





A simple way to avoid mixing them up is just to leave each line hanging in the relevant injector well. Another tip is to take a photograph of the arrangement, or you could tie a small label on each one.

Once you've removed all 6 lines, you should be looking at this:



You can see we've grouped 4 injector lines together on the right of the pump, the other 2 are at the left of the pump out of shot. If you look closely, you can see diesel welling up at the top of each delivery valve (its blue).

4) Remove splined collars

Each delivery valve is held in place by a splined collar. This collar is designed to stop the delivery valve from moving once it has been torqued to the fuel pump - if this collar wasn't there, then once you put the injector line on the valve and began tightening it, the delivery valve would start rotating in sympathy.

There are 6 collars, held in position by 3 bolts. Remove all 3 bolts. The collars will be stuck to the head with age and grime (and diesel). Get a flat bladed screwdriver and bend it 90' in a vice - this gives you a nice lever to get them up. Work them back and forth, they'll start moving. Then just lift them off.



From the picture above you can see the installation order - collars 1, 3, 5 are first on, followed by 2, 4, 6. They overlap.

Attached Thumbnails

         

Once all 6 collars are off, you should be looking at this:



The collars will be filthy - chuck them in a bucket of degreaser for now.

5) Removing the delivery valves

With the special Mercedes tool, unscrew delivery valve 6 - carefully.



As the valve is removed, there will be a tall slim spring resting inside the pump - take care this doesn't fall out into the engine bay.



The o-ring should be above the thread on the valve you just removed - if it isn't there, it will be stuck in the fuel pump here:



(you can just make it out, above the thread)

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In the image above you can see the crush washer (part 7f). This needs to be removed. Insert the end of a flat screwdriver under the lip of the washer, and gently slide it out.

Now the crush washer rests on a metal collar, the collar holds a very small cylinder of metal. This cylinder, from what we could gather, when the engine is running pushes against the spring and allows a small amount of fuel up the lines, through the injectors, and into the engine. I have been repeatedly warned not to disturb this but to my surprise the collar and little cylinder were quite happy to slide around inside the pump - they can't really not move, because the pump isn't horizontal anyway, its tilted to one side.

I think what may have happened is that someone has torqued the delivery valve back down, not taking care to ensure the collar is correctly centred in that little well, and the little cylinder hasn't been able to fully move - which would probably lead to damaged seals inside the pump, and a damaged delivery valve. With respect, its easily done as 7g moves around a fair bit, and the spring is carefully balanced - so take great care here.

Anyway, we removed it just to have a look:



There appear to be no keyways or anything, the pdf file (I will link it at the end) just says "observe the installed position". There is a groove along one edge, we just compared it to the collar on valve 5 and aligned it in the same direction. The little cylinder is flat to the top edge (with a small serial number stamped in), the bottom edge looks like a phillips screwdriver blade - probably so the diesel can counteract the rotational forces applied on the top edge when it pushes against the spring.

Obviously you don't have to remove this collar or the little cylinder, so don't unless you're curious. If you do remove it, make sure it goes back in the correct orientation, and clean.

Put the new crush washer in place, and slide your new o-ring over the thread of the delivery valve. Your fingers will be covered in diesel and oil anyway, but if they're not just make sure the o-ring is wet with oil/diesel, to ensure a better seal while torquing down.

Carefully put the spring back in the pump, and ensure the collar (7g) is centered in the chamber.



Screw the delivery valve back down with your fingers, waggle it back and forth as you do so the collar, crush washer, and spring are all forced to align themselves correctly inside the delivery valve (the inside of the valve is slightly fluted to aid this).

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Repeat the above steps for the 5 remaining valves.

6) Putting things back together

Once the valves have all been screwed in by hand, get the torque wrench out and torque each valve up to 26 ft/lb (35 nm). Slide the collars back over the spines (taking care to observe the order they were removed), and screw the collars back down with the 3 screws. You should be looking at this:



Screw each injector line back onto the valves, starting with line 1 working through to line 6. No torque figure for these, just tighten them up, then an eighth/quarter turn more, and that should be that. Then screw each line back onto it's injector, observing the same degree of tightness:



Take care that the fuel lines are correctly aligned - there are plastic clips to guide them. Watch that no plastic fuel lines get in the way.

Reinstall the intake manifold - this is a pig of a job and you'll need 4 hands to do it. Theres no way to describe it, just put it back together (refer to the EGR thread if you like). Use gasket paste to ensure a better seal between the manifold and the head (we reused the existing gasket, its metal and still a good seal)

You can of course clean the oily crud from the intake manifold if you like, and the EGR as well. You'll need a bottle brush and some degreaser for that.

7) Crank like crazy

This is where your battery gets tested. There will be loads of air in the system now, and you're going to have to crank for a good 2-3 minutes (crank no more than 10 seconds a time, with 20 seconds inbetween).

My battery gave up the ghost here, so I nipped down the local autofactors and bought a new one. Well its had a good 5 years anyway, and was getting a bit tired. Plus I got it at trade price, so it only cost me £50

Eventually the engine should fire back to life, it will stumble a bit but once the air has been pushed out the system it will be fine. Leave it running for 5 minutes to restore some charge to the battery.


I did have a heart in mouth moment on the way home, a massive THUNK from under the bonnet - fortunately it was the pipe from the turbo popping out of the EGR valve under the manifold. Either not inserted fully, or a clamp has broken, either way at least it wasn't the fuel pump exploding

Bigger pictures here:

http://www.flickr.com/photos/soundman/sets/72157603792018546/

Heres a picture of the reason why they were all leaking:



And here's a very square (should be round) cross sectioned o-ring:



Hope this all helps!

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That's an excellent writeup.

Would it be OK if the Webmaster put it in the DIY Wiki forum?

The photos are fantastic.

Sure

The photos won't ever disappear, but just in case feel free to visit the Flickr site and download the full resolution versions. You have my permission to use any of them for whatever you like.

Thanks.

That's going to help a lot of folks.

The danger of failing to reseat the valve properly results in the requirement for a new IP.

Great photos and write up. I would only add two things:

1) I did not find it necessary to remove the hard lines at the injectors, they will move out of the way far enough once you take them off the delivery valves to be able to remove the valves.

2) You apparently didn't clean the top of the IP before taking it apart...this is a BIG NO-NO. It is a much better practice to thoroughly clean the top of the IP off so none of the crud falls into the DV holes or threads! That is the step that should come right after removing the IM - CLEAN OFF THE CRUD! I used brake cleaner, a toothbrush and compressed air.

I also found it very challenging to get the spring to stay balanced on top of the internal DV cylinder so I put a very minute amount of clean white lithium grease on the base of the spring to act as a "glue" to hold the spring in perfect orientation while I screwed the DV cover back on...just another tip.

I also kept a glass full of clean diesel that I dunked everything into (the springs and the DV cover) before re-installing them. That way any dirt would get washed away and the new ring would be well lubricated before screwing it down...one more tip.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Excellent write-up and suggestions. Now I won't feel too concerned if I have to redo my delivery valve seals.....

__________________
#dieselFLEET
---------------
'97 E300
'99 E300

I thought about that, but believe me none of that gunk was going to move. It was oily diesely gunk. Trust me, the close up photographs make it appear much worse than it was

Thanks P of D!

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Thanks for the great DIY!

It's already in the Wiki HERE.

__________________
Bill Wood - Retired Webmaster
My Personal Website
1998 Mercedes E430
2010 Toyota Sequoia
My Photo Albums

Outstanding writeup and pictorial......takes a lot of the guesswork out of doing the job. A-1 info.

__________________
96 E300d

Great write up, and photos. I downloaded the lot of them from your site - thanks!

I have to learn how to get my photos down to the allowable size to post, and still have them show any useful detail.

How often is this job necessary? I am just beginning to notice a slight smell of Diesel and a loss of fuel efficiency in my 1998 with 162,000 miles. I inspected the top of the injection pump the other day and noted it was grimy and wet looking, and with my nose in the vicinity the Diesel fuel odor was pretty strong. I get no spots on the ground though, so the leakage rate is pretty low - seems it must be evaporating at nearly the same rate it is leaking.

Thanks again, I will be off to find the Viton O-ring thread, and gathering the parts. I will likely replace most of the fuel line seals at the same time. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

1 shutoff valve 2.5mm x 12mm ID
9 fuel line 2.5mm x 8mm ID (1 located at fuel filter housing)
3 fuel filter housing 2.5mm x 10mm ID
1 pre-filter 3mm x 18mm ID

1 O-Ring for in-tank fuel screen/filter 3mm x,35mm ID / 41mm OD.

Anyone know the lsize of Delivery Valve o-rings?

__________________
#dieselFLEET
---------------
'97 E300
'99 E300