Is the delivery valve basically a check vavle? Is there a spec for it's opening and closing pressure? Has anyone come up with a way to test a delivery valve other than when they are installed in an IP on a Bosch test bench?

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Not knowing the history of your car regarding any work done to the delivery valves, below is what happened in my case when mine started leaking. It was an easy fix in my case. Good luck!!



When my 96E300 d delivery valves started leaking externally, I decide to repair them. Prior to me doing the repair, the engine ran smooth as silk at idle. The first time I did the repair, I did not change out the copper crush washers. A number of posters indicated it was not necessary to do so. The leak was fixed, but when I started the engine, it was nailing, which it had never done before. After driving the car for about 100 miles, the nailing was still there, and I decided to do the delivery valves again, only this time changing out the crush washers. Long story short, the idle was back to normal and smooth as silk.

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96 E300d

Yep, I read post #10, and I appreciate you chiming in now. How similar was the nail you experienced and cured to that which is in the video I linked to?

We've had the car a few months now and have put a bit more than 2000 miles on it. I've not touched the delivery valves and I have no idea if anybody ever has - no records of it. FWIW the engine seems in good shape - no noticeable consumption of oil, crank case breather system isn't full of oil, and the oil filler cap doesn't dance from blowby at idle.

Greg, yours is doing nearly exactly what my SDL is doing. Mine starts out fine when it's cold, but as it gets to operating temp, it gets worse until it behaves nearly identically to yours, right down to the RPM ranges.

I've serviced everything in my system EXCEPT the DV's. I have the parts on order and will report back when I've done that job whether or not it made any difference.

At idle, mine has a soft miss (distinctly less than a dead cylinder) that goes away with any throttle at all. On the road, it's smooth as glass, but with that nailing right up to around 1300 RPM or so, then silence anywhere in the normal driving range.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

I'd recommend trying a diesel purge treatment first, running the engine on straight diesel purge through a complete can, HOT engine before you start. Assuming your car has delivery valves similar to earlier engines: If that doesn't clear it up, then by all means rebuild the delivery valves with fresh copper washers, springs, and o-rings.

Yes, I will run a can of purge through it before committing to messing around with the delivery valves - easy enough. I appreciate the input.

Thanks for chiming in on this, Diseasel300. I'm curious to see how it shakes out with your engine, so please do keep us posted.

What did you order exactly, and from whom? I know part numbers are listed in other threads, but it would be nice to have them here too.

I won't be getting into the job until the weather warms up. Moving to SLC meant giving up the heated shop, and I don't much like working on cars out in the cold, snow, ice, wind unless I really have to! When I get around to it I'll probably isolate the nailing cylinder (I think it's in the middle, #3 or #4) and just do the seals and spring for that one, assuming a purge doesn't clear it up.

Anybody in the SLC area have a shop space they can share?

I have found changing the delivery valve seals can affect the running in a few ways, timing and mixture being the two obvious ones.

New seals seem to need a certain amount of bedding in once changed, mine on this 606.910 took around 500 miles before the rich mixture level dropped to normal - a buddy did a 605 but skipped the full procedure, pinked badly for 20k before finally bedding down.

If you have a worn seal (or weak spring) it will not provide the necessary 'hydraulic lock' for the injector nozzle to open, this force is generated by a small cam inside the pump.

If so, the nozzle may open late which could cause nailing.

It's an easy job to do but a good low measurement torque wrench is essential for two stage torquing.

Use a barbecue wooden skewer to through the copper crush washer, place pointed end where you want to position - works well, less fiddly.

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

That's good information, spock505. Thanks for sharing.

I've replaced delivery valve seals before on OM615, OM616, and OM617 engines so the process isn't foreign to me. FWIW I prefer beam type torque wrenches, and I have three covering light to heavy torque values.

That's a great tip for getting the new crush washers down where they belong.

No problem - as a test, you could always try adding something to the tank for increased viscosity.

One of the things veggie drivers usually report when first using veg is how quiet the engine is, this can in part be caused by higher viscosity 'fuel' creating a better seal on previously worn parts.

(not advocating using veg, but as a short test works well)

btw, if you haven't removed the manifold before on 210 there's a really awkward bolt which needs to be accessed from underneath.

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

I will definitely follow up when I get the DV's serviced. I'm waiting on parts currently, ordered from Mercedes of South Atlanta and had a couple of other parts in the mix that are holding the order up.

I ordered the springs, copper washers, and o-rings.

Mercedes part numbers (Keep in mind this is for an OM603, part numbers for other engines may be different):

Springs: $3.70 - 0010743493
Washers: 90˘ - 0049974540
O-Rings: 90˘ - 0179974148

I opted to order from Mercedes directly vs our sponsor due to the difficulty I've had getting the springs in the past (nobody carries them and they take just as long as ordering from MB).

I've also done the diesel purge route on my car. While running on the DP, it was truly shocking how quiet the engine was. I had a helper with me when we did it, and we'd walked away while it was starting the purge and thought it died. Nope, just REALLY quiet. Soft miss was still present at idle, but the nailing and clatter was reduced to nothing. I'd serviced the tappets in the past, so it sounded like a gas engine quietly purring along. After the DP was done and it was back on straight pump diesel - business as usual.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

The nailing I had was just like yours, which was not there before I did the delivery valves the first time. When I did them the second time changing out the crush washers, the nailing was gone as soon as I fired it up.

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96 E300d

Thanks for posting that!

Visited the local Bosch shop today. I wanted to get hold of the sealing washers, springs, and o-rings for doing this job on the '96 E300. Here are the Bosch part numbers for these parts:

- 1 410 105 021 - Gasket (the copper sealing ring)
- 1 414 611 024 - Compression Spring
- 1 460 210 321 - O-Ring

I also dug a little and found that these parts are good for all OM60X engines with mechanical injection.

I actually had them order a gasket kit for the IP. Comes with the DV related seals, as well as the other gaskets and o-rings that go on this IP. When I get it I'll post the part number for this kit. This kit does not include the compression springs, so those were ordered separately.

And, the super nice fellows over at Goff Diesel Injection shop are going to let me use their special delivery valve socket when I get around to doing this job.

As promised, I'm following up with this tread. My parts *FINALLY* came in today and I did the job this evening.

First thing I noticed right away is that the DV holders have been off my car before. The gorilla who did it before didn't bother to thread the hold down screws in by hand, so 2 of the 3 were stripped into the IP block. *sigh* Once I got those out and started undoing the DV holders, it became obvious that they were never torqued. I had the torque wrench set on 20Nm and it never clicked once on any of the 6.

I did one DV at a time, and on each one, as I took the holder off I noticed that the whole chamber was filled with some sort of cloudy stuff. Not sure what it was, but it certainly didn't come from outside the chamber (I had the IP well cleaned before I touched anything). I used some clean diesel in a dental squirter to flush out all the nasty crap in the chambers before replacing the sealing rings.

The new springs I installed were easily 2mm longer than the ones I pulled out. A fairly significant difference! The wire size and coil density appeared to be the same, the old ones were just compressed about 2mm compared to the new ones.

Finally got finished and torqued the holders in place doing the 30,30,35Nm tightening routine.

Cleaned everything up and decided to flush the DV's before I put the injector lines back on. Dropped a rag over the DV's, put the accelerator to the floor and cranked through a good couple dozen rotations before putting the hard lines back on, just in case any of that murky crap was still in there it got flushed out.

After putting everything back together, gave the engine a good long glow, pedal to the floor and cranked. After about 4 or 5 compression hits it fired right up. No smoke (which surprised me!)

After letting it idle for a bit, it became very obvious that my loud nailing was gone and the car was new running on 6 cylinders instead of 5 1/2. Went and drove it around town, on the highway, through the country, and all over the area to get it good and hot. Nailing hasn't returned, and my idle is still on 6 cylinders. Idle is still ever so slightly rough (nothing objectionable), but no longer rocking the car and clattering like a man striking an anvil with a hammer.

The biggest change (and this is a big one): no more grey smoke at idle, and no more leaving clouds of smoke when putting the throttle hard down. Was driving it in traffic this evening, and not once did I see a haze behind me. For a car that earned its nickname of "Diseasel" because of the smoke it carried around behind it, that's a MARKED improvement.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]