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  #1  
Old 01-30-2018, 10:29 PM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 223
95 e300d w124, questions about injection pump and delivery valves

Making my 1st attempt to change the copper washer and o-ring for the delivery valves.

Four of my delivery valves were fairly easy and seemed to be ok. The 1st two nearest the fuel filter seemed to act different from the other four. The stainless cylinder ( that the copper washer goes on top of ) seemed to want to wander like a hockey puck on ice.

Questions:

Is that easy free movement of that stainless cylinder normal?

Does changing just one delivery valve cause the injection pump to lose diesel back to the tank?

I changed just one to begin with and found that the engine made no attempt to fire until it had been cranked a seeming long, long, time. I must have tried to get it to fire for about 10 attempts before it started to fire. Acted like the injection pump had no diesel for any of the cylinders. Acted like the pump had lost it's volume of fuel for all the cylinders - not just the first one I changed.

Question on copper washer

The way the old copper washer looked, it seems they would do a better job of sealing than the new copper washer. Old one was polished smooth compared to the new one.

Is changing the copper washers really required? Or just changed because it's been opened up?

Question on o-ring for delivery valve

There seems to be enough room on the delivery valve top that unscrews to put two o-rings side by side. Has anyone tried two o-rings? Seems it would seal tighter and possibly last longer.

Torquing question

After the delivery valve top has been hand tightened, My torque wrench clicked at less than a 1/4 turn more. That way for all six. Is that about normal for others? Just checking to see if my torque wrench is still in spec.

Snap-on wants about $60 for a calibration check. But it takes three weeks turnaround.

Thanks to others that have entered posts on how to do this job. Made it much easier than expected.

- white lithium grease to help hold spring upright
- thoroughly clean top of pump 1st
- I used a plastic ramp below the front wheel to help make the pump sit more vertical ( supposedly helps keep spring from falling over ). Raised wheel about 7 inches.

I replaced all the old springs with new Mercedes ones from Pelican Parts. Measured length of old and new.

New ones were .995 - .998 inches long.

Old ones replaced measured close to .946

That's how my tool measured but that tool is fairly old now.

Used viton supposedly will last longer.

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  #2  
Old 01-30-2018, 10:49 PM
Diseasel300's Avatar
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Join Date: May 2016
Location: Texas Hill Country
Posts: 4,934
The steel barrel you had skidding around in the actual delivery valve body. It is just sitting there, so it is free to move. It is held in place by the delivery valve holder (the part you took off to do the job).

Depending on which DV you removed first and which part of the stroke it was on, the diesel can drain out of the fuel rack. If there is a slight vacuum on the fuel tank, it can suck the rest out once you open up the DV chamber since the pumping element now communicates freely with the atmosphere. After doing a DV seal change, you have to anticipate re-priming the fuel system, which normally takes at least a 30 second crank. Sometimes two.

Don't double up the O-ring. Get enough rubber in there and your torque readings are meaningless and you run the risk of not seating the DV holder.

The torque value 30nm-30-nm-30nm-35nm is not very tight. More like "snug". That is why the retaining rings are there, to keep the DV holder spinning when attaching the hard fuel lines.
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  #3  
Old 01-31-2018, 08:29 AM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 223
Thanks Dieseasel300, makes sense about the retainers. I just didn't understand why four of the six stayed close to center while the other two were harder to keep centered.

On the o-ring, I noticed that the groove for the o-ring was not completely filled by the old o-ring. Just thought two might make it more reliable.

I have the fuel cap off the fuel tank so the fuel wasn't sucked back. It must have gravity flowed from the pump back to the tank when the pump seal was broken by removing the one delivery valve top.

Is about a 1/4 turn past 'finger tight' normal, 'to reach torque setting'?
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  #4  
Old 01-31-2018, 10:23 AM
Diseasel300's Avatar
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The DV's are free floating in there, if there's a bit of varnish or other crap accumulated under the 4 that stayed centered, they'll tend to "stick" in place. I wouldn't lose sleep over it. In a perfect world, they'd all move, but this world is far from perfect.

The O-ring needs room to "grow" in the slot as it is compressed. If you pay attention to the top surface of the IP, the holes for the DV holders are bevelled. As you tighten the DV holder down, it pulls the O-ring into the groove and flattens out. If you look at your old ones, they'll have a more or less square profile to them. They leak because the rubber hardens and shrinks slightly as it ages. Kind of a stupid design, but it should go for >10 years before you have to do it again. Less if you run biofuels.

Every time I've done DV's on my car, I've had to reprime the IP. There's no positive "check valve" in the return fuel line unlike the old 617's, so as soon as you expose the fuel rack to air, gravity will pull the fuel in the return line back to the tank along with anything it can suck along from the fuel rack.

35nm isn't very tight, more like snug. If you got the DV holders screwed down almost all the way by finger tightening, then 1/4 turn seems about right.
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  #5  
Old 01-31-2018, 10:30 AM
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Join Date: May 2007
Posts: 851
It is not recommended to use a click type of torque wrench to do this job.

The 3-stage torque procedure for the barrels is 30Nm, release, 30Nm, release, final torque 30-35Nm.

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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OM606 engine (W210 E300D/TD) delivery valve seals
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  #6  
Old 02-01-2018, 05:50 PM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 223
Really good input on the copper washers. Doubtful if I ever have to do my delivery valves again. But I was thinking about leaving them in next time. Now I won't do that.

Click type is the only type I have. From my reading the regular consumer type torque wrenches are better than hand tight but they still have a fairly wide margin of error.

Will be buttoning up the intake & vacuum butterflies over the weekend. So far runs good and no fuel seeping out.
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  #7  
Old 02-07-2018, 09:48 AM
WTB: 94/95 E320 Wagon
 
Join Date: Oct 2007
Location: Charleston SC
Posts: 2,687
Quote:
Originally Posted by pimpernell View Post
The 3-stage torque procedure for the barrels is 30Nm, release, 30Nm, release, final torque 30-35Nm.
This is correct and must be followed, or there is a risk that the proper torque won't be achieved or the DV may bind and warp the body of the injection pump.

Just one addition: The final torque step is to torque the DV to 30Nm, and then torque it to 35Nm (two-stage torque).

Why three steps, and then last step has two stages? The first two steps ensure that the DV and internals are all straight and seated and the o-rings find their place. The last step with two stages does the same (belts + suspenders + holding on with both hands) AND then the higher final torque crushes the copper washer a bit more to ensure a good tight seal there.

As pointed out, the copper washer MUST be changed or softened so that it can form a good seal, as it has been work hardened from the last installation and subsequent use. If you are in a tight spot and don't have a new washer, try this. I have not tried this, so no promise it will work, but may be worth a shot to get the car back on the road. An old washer can be softened and reused by heating with a torch until glowing nice and orange and then allowing to cool. Suspend on a piece of steel wire for this step. Clean it off really well to get any carbon or oxidation off. DO NOT use sand paper - that will leave grit embedded which will then scratch up the internals or worse let go and do damage internal to the injection pump or to the injector. Use brake cleaner or alcohol and a clean cloth to polish it up.

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M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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