OM603 602 601 Lift Pump Re-Seal (O-Rings)
 

Out of the 3 injection pumps I've had for my SDL, only one of them had a lift pump that was any good. I tested functionality in a highly scientific way: I put my fingers over the inlet and outlet holes and pumped the plunger. Only 1 pump generated any meaningful pressure at the outlet port and so it got installed in the car.

Flash forward a couple of months and the car just isn't running as sweet as it was. Idle is fairly rough and that first start in the morning can be a little rough. The final straw came earlier this week when I punched the gas to merge on the highway and left a huge cloud of white smoke behind the car. :eek:

Got home and started doing some checking. Noticed some diesel leaking out of the injection pump body. Pulled the dipstick and had about 3 quarts more oil than I put in it! Reeked of diesel. Uh oh!

I immediately pulled the lift pump and operated the plunger by hand, with diesel leaking out all around the plunger as I operated it. Time to see if I can rebuild this thing.

I took one of the spare pumps and pulled it apart. Searching the web seems to make these pumps out to be non-serviceable and made of magic. I don't buy that, the top and end unscrew! In the case of the pump I've serviced in the pictures below, the suction side was good (easily created a vacuum against my finger and held it), but the supply/pressure side was pretty wimpy and would not hold pressure.

Testing the check valves (disc valve style) showed they sealed fine and the piston wasn't scored or loose in the bore, so I decided to replace the 4 O-rings in the pump. All 4 were ROCK HARD, the one on the plunger shaft was so worn that it no longer even touches the shaft.

Post-reseal has the pump generating meaningful pressure, and more importantly - HOLDING IT against my finger when I operate it by hand. No more leaking of the plunger either. The real test will be when I get it in the car and test it (need to change the oil first!).

For those interested, I've labelled the exploded diagram below with the O-ring sizes (red text). I don't run biodiesel so I didn't bother with Viton O-rings.

If you do service your lift pump, do yourself a favor and clean it out well while you have it apart. Mine was full of black goop and came right off in mineral spirits. When you reassemble the pump, give everything a dunk in oil before you put it together. You'll prevent any metal-metal rubbing of the piston/bore that way. The small O-ring in the plunger bore is a real pain to get put back. A tip I tried was pushing the plunger up behind it and pressing it in place with a toothpick.

And finally, I have quite a few O-rings left over. If you want to save yourself the trouble of sourcing them, PM me and I'll be happy to send you a set. We'll call it a buck-50 to cover postage and the cost of the O-rings.

As a followup, I did an oil change and swapped out the lift pumps today and went for a drive. Primed the fuel system by pumping the plunger by hand and heard an alarming amount of air bubbling up in the fuel tank. Lift pump that was on the car was still making decent pressure, but diesel freely dripped out of the plunger bore.

Car cranked right up and was immediately obvious that the idle was much smoother and a lot quieter (noticeably so). After arriving home I checked the injection pump body for diesel streaks and it was bone dry. Seems to be well worth the effort and certainly saved shelling out big bucks for a new lift pump.

Hey Diseasel...Thanks for the write up. I'll take a set and renew my 30 year old O-rings. PM sent.

Not All Can Be Saved
 

Adding to this writeup:

Not all lift pumps can be revived like the one I showed in pictures. I went to rebuild the lift pump I pulled off the car last night, and it is a prime example of when to give up and cut your losses.

A few things worth checking out before tearing down the lift pump:

With the pump out of the car check it's functionality. Place your finger across the intake and pump the plunger several times (hang onto it, it isn't attached to anything and can come shooting out of the pump body!). If the pump is still gurgling and trying to pump and/or you are not developing any vacuum against your finger, your pump is probably too far gone to save. If you do develop vacuum against your finger, stop and count to 3 then remove your finger. If you held vacuum, your lift valve is good.

Repeat the above procedure, but with your finger pressing firmly against the outlet of the pump (threaded fitting). You should build some sort of pressure, it may not be much, but you should build some and it should hold. If you are not building pressure, or if the pressure you do build leaks down quickly, your supply valve may be toast.

If the pump passes the above checks, take it apart. It is easiest to use a vice, that first 1/8 turn can be really difficult if the O-ring has welded itself in place.

When you get the pump apart, inspect the internal parts. If you see heavy scoring on the piston (shown below), cracking of the valve discs (shown below, would you trust that?), or polishing of the pump bore (shown below, no, that is not a wet spot), your pump is likely past its prime.

After re-sealing and tightening everything, fill the pump with motor oil and test it. you should be able to develop a healthy vacuum (and hold it) and develop a healthy pressure (and hold it too). If you don't develop vacuum/pressure after rebuilding and sealing, reinspect your disc valves for cracks, warping, or poor sealing.

Lastly, don't forget to double check your fuel line fittings after reassembling everything. I made the mistake of not checking my supply side fitting and have been driving around for the last 2 days with it loose! :eek: A lady at the post office pointed out the puddle under the front of the car this afternoon and avoided certain disaster. Surprisingly the engine had no issue running, even with that big leak! Double check your work... :o

FOR FUTURE REFERENCE
 

I have a 1983 240D and Mercedes stocks a SEAL KIT (O rings) for $6 and they stock the gasket for $2.


Mercedes will need your engine number to find the parts.

This thread was for the later engines with a different style lift pump than your 240D uses. The older pumps for the 61x series engines have a rebuild kit, the newer ones don't. They're rebuildable if you have the parts to do it, but Mercedes (nor Bosch) sell a kit, they only sell the complete pump assembly.

Sending PM - I'll take a set if of the pump o-rings if you still have a set.

Great helpful post for many. High milage lift pumps probably should be reconditioned anyways. Increases reliability alone mind running issues.

Pro active service to prevent or reduce the chance of road breakdowns to me always has been money and time well spent. I have had two disabling road breakdowns over the last thirty years

. I was lucky in both cases. Because of the age of these cars and the possible wait for parts. Plus most remaining garages are booked already. A road breakdown away from home can besides the loss of probably a day at least. Land up being pretty expensive.

Going to the law of averages the poster had three injection pump assemblies. He found only one semi decent lift pump on the three of them. Even it became problematic after a short period.

So there have to be a lot of marginal lift pumps out there on the road currently. I do not own a 603 but he has shown that they can be reconditioned where there are no rebuild kits available for them in at least some cases.

As for testing your lift pumps general current condition on the engine. Get a pressure gauge connected anywhere past the lift pump. Close off the return line from the injection pump. You want to see probably at least thirty pounds with the engine running. You will need a liquid dampened gauge.

Not a conclusive test but far better than knowing nothing in my opinion about the lift pumps condition. This test is also applicable to both the 6O3, 617 and 616 engines. Actually probably on any diesel engine with the same setup basically. There will be cases where we have absolutely no history on what has and has not been replaced before we owned these cars.

He cannot provide replacement o rings for everyone of course. He could list the sizes of the ones required as a helpful guide. That could help many. This member has already given a lot of help to others through his thoughtful approaches on other issues.

All I can contribute is the thought. The better piston seal in the bore you have the better of course. The way that piston operates in service might still tolerate some leakage with no dire consequences. The frequency of fuel pressure pushing it back against the regulating spring is once every two engine revolutions.

Not absolutely sure of this though. The piston to bore is metal to metal. That said obvious issues with the piston or bore will override this thought. I would ask the wife for verification but she is currently on the phone.

I don't know if these apply or not but there was kits for them.
Newer Lift Pump Repair with Disc Valves
http://www.peachparts.com/shopforum/showthread.php?t=285915
606 Fuel/Lift Pump Rebuild
http://www.peachparts.com/shopforum/showthread.php?t=288883
http://www.peachparts.com/shopforum/mercedes-parts-reference-library/240104-om606-910-diesel-lift-pump-repair-kit.html

http://www.peachparts.com/shopforum/diesel-discussion/288883-om606-fuel-pump-rebuild.html
So if there is no kits you have the individual parts.
000 091 10 19 SPRING
000 091 13 10 VALVE (X2)
023 997 87 48 SEAL RING
023 997 86 48 SEAL RING
000 091 17 80 GASKET
021 997 88 48 SEAL

An excellent write up complete with an unintended (or perhaps not) pun!

YI think the check valve is most important. It trumps over o-rings. It seems that it is NLA. The pump is very simple, a lot of the time the problem is the check valve, it will pump 'OK'-ish with a cracked disk if it is fully primed. If you run out of fuel then a crack disk will not cut it.

I am wondering why Bosch, some european knock off company or China would not have kits or seperate parts.

The older Fuel Supply/Lift Pumps have an aluminum plate on them that has the model number of that pump and the newer one have it stamped into a flat spot on the aluminum body.

The 2 Valves 000 091 13 10 VALVE Below is a site that has parts interchange numbers for the same as it turns out popular valve including the Bosch part number.
https://jrsauto.com.ua/p199435345-klapan-tnvd-200231.html Parts interchange


Below is a video I found on testing the Lift Pump Outlet Valve.

https://www.youtube.com/watch?v=795GrIEAc_w

I believe this is the Bosch number for the 606 engine lift pump kit. I also believe it is the same as the 601 Engine but have no proof.
2447010021 BOSCH
This is a site with pictures. 2 valves 2 different sized O-rings and the little O-ring for the push rod.
2447010021 KOMPLET ZAWORKÓW POMPY PALIWA BOSCH - Bosch - BOSCH - Auto Diesel Parts Lublin - hurt detal

From what I've been able to tell, the 601/2/3 and 604/5/6 lift pumps differ mainly in the fuel line connection and delivery check valve. The 601/2/3 style uses a clamp/flare for the fuel line while the later ones use some sort of quick-fit connection. The final check valve appears to be a slightly different design from the pictures I've seen, though it could just be down to how the diagrams are drawn. The 601/2/3 style uses 2 of the same valve, one in the piston, the other as the check valve with an O-ring as the seal. The later style looks as if the delivery check valve is part of the outlet fitting somehow? I don't own a 606 engine, so no first-hand knowledge. The video linked above seems to show the 606 style delivery check valve.

I do find it sad that there don't seem to be any English sources for the disc valves. If there are, they sure are well hidden. I'd love to have a couple sets just to replace the 31 year old ones in my pumps (one of which has cracked discs), but I'm not about to deal with some company with a website I can't even read, much less know how much I'm paying.

Typing the part number into Pelican's site shows it's a special order part for $9.50, but makes no claim it'll fit or gives any other info. Not sure I want to waste $20+freight for something that may be the wrong part.