Frustration With Factory Service Manual On Installing OM621 200D Injection Pump

[Squiggle Dog]

I am having a very hard time understanding the factory service manual on installing the recently serviced fuel injection pump in my 1968 W110 200D OM621. I don't know what I am supposed to do at this point. I have the engine set to 47 degrees BTDC, or at least as close as I could get it since it moves so jerkily.

The factory service manual states that the first cylinder must be in its compression stroke position. As opposed to what, exhaust stroke position? How am I supposed to know if the first cylinder is in compression stroke position?

Then it states that the injection pump must be placed in start delivery position, meaning the mark on the splined collar lines up with the mark on the pump. It looks like that's the way I got it back, so that part is fine.

Then it says so apply "light leftward oriented pressure to the drive collar, opposite to the direction of rotation". Then it reads, "Cam pressure of the camshaft causes the drive collar to jump back two teeth to the cam base circle. The second tooth must then coincide with the marking on the injection pump housing."

What is that supposed to mean? I'm assuming the pump turns clockwise when facing the engine. Is the mark on the pump supposed to line up with the second tooth on the drive collar (and what side?) instead of the missing tooth? I rotated the drive collar and found that I couldn't get the missing tooth and the mark on the pump to line up anymore.

Then there is a note: "Because the drive collar jumps back by two teeth, crankshaft adjustment to 47 degress BTDC is necessary." Once again, I have no idea what this means.

This whole "apply light leftward oriented pressure to the drive collar", the drive collar "jumping back two teeth", and the first cylinder "in its compression stroke" is confusing me and now I don't know what to do.

The pump is resting in the engine with the "missing" tooth on the drive collar almost aligned with the mark on the pump. I couldn't get the marks to line up perfectly after rotating the drive collar. The engine is set at 47 degress BTDC and I have no idea if the first piston is in its compression stroke. And what if I'm off a tooth or two?

Where do I go from here?

[Billybob]

Originally Posted by Squiggle Dog

I am having a very hard time understanding the factory service manual on installing the recently serviced fuel injection pump in my 1968 W110 200D OM621. I don't know what I am supposed to do at this point. I have the engine set to 47 degrees BTDC, or at least as close as I could get it since it moves so jerkily.

The factory service manual states that the first cylinder must be in its compression stroke position. As opposed to what, exhaust stroke position? How am I supposed to know if the first cylinder is in compression stroke position?

Then it states that the injection pump must be placed in start delivery position, meaning the mark on the splined collar lines up with the mark on the pump. It looks like that's the way I got it back, so that part is fine.

Then it says so apply "light leftward oriented pressure to the drive collar, opposite to the direction of rotation". Then it reads, "Cam pressure of the camshaft causes the drive collar to jump back two teeth to the cam base circle. The second tooth must then coincide with the marking on the injection pump housing."

What is that supposed to mean? I'm assuming the pump turns clockwise when facing the engine. Is the mark on the pump supposed to line up with the second tooth on the drive collar (and what side?) instead of the missing tooth? I rotated the drive collar and found that I couldn't get the missing tooth and the mark on the pump to line up anymore.

Then there is a note: "Because the drive collar jumps back by two teeth, crankshaft adjustment to 47 degress BTDC is necessary." Once again, I have no idea what this means.

This whole "apply light leftward oriented pressure to the drive collar", the drive collar "jumping back two teeth", and the first cylinder "in its compression stroke" is confusing me and now I don't know what to do.

The pump is resting in the engine with the "missing" tooth on the drive collar almost aligned with the mark on the pump. I couldn't get the marks to line up perfectly after rotating the drive collar. The engine is set at 47 degress BTDC and I have no idea if the first piston is in its compression stroke. And what if I'm off a tooth or two?

Where do I go from here?

If the injectors or glow plugs are removed that should avoid the "jumpiness" if it associated with cylinder compression while your advancing the engine rotation.

The compression stock would be when the piston is rising and both intake and exhaust valves are closed, I'd assume.

Can't help on the specifics of the install as I haven't done that job . Good Luck!

[cth350]

here is an older threads on the subject...

http://www.peachparts.com/shopforum/showthread.php?t=282642

HTH -CTH

[Diesel911]

2 ways to tell if #1 is on the Compression Stroke.

Remove the Valve Cover and observe if both the Intake and Exhaust Valves are closed on #1 cylinder.

Remove a Glow Plug and carefully shove your Finger in the hole. When it starts up on the compression stroke you will feel Air pushing out on your finger.
If the Fuel Injectin Shop did not put Oil in in your Fuel Injection Pump; after it is on the Engine you need to add Oil.

The only instrctions I have are fore ao 615 Engine but they appear to be the same.
You turn the Fuel Injection Pump Drive Gear clockwise until the flat/missing tooth or teeth lines up with the marke on the Fuel Injection Pump Bearing Flange (at about 11 O'clock).
Because it is under Fuel Injection Pump Camshaf is under spring tension they want you to put a little counter clockwise turn and let the spring pressure roll it back counter clockwise 2 teeth. That relieves the spring tension.

At that point with the Crankshaft timing marks at 47degrees BTDC on the Compression Stroke you stick the Fuel Injection Pump into the Engine but stick the Pump in so that the Slots where the Bolts or studs that hold down the Fuel Injection Pump are centered in the Slots (so you are able to rotate the Fuel Injection Pump either way).
Install the Bolts or nuts that hold the Fuel Inection Pump to the Block.

Next you need to do what is neccesary to do the Drip Timing.

[Squiggle Dog]

I made sure the camshaft lobes were pointing up and the timing marks set to 47 BTDC. I then inserted the pump with the marks aligned.

The car started and ran but was smoking here and there. I played around with the positioning of the pump (bending the hard lines each time is a PAIN) but it didn't seem to change anything.

I loosened the line for the first cylinder at the pump to look for fuel bubbling out as I turned the engine but didn't see any. I then pulled out the first delivery valve and attached a drip tool. Fuel would pour out and then start to drip at a moderate rate at around 50 BTDC. At 26 BTDC the fuel would start to pour out again. I couldn't find a place where the drips stopped and got sick of messing with it.

I took the car for a test drive and it was somewhat lacking in power, smokey, and ran a bit hot. I don't think I feel like messing with it anymore. I am going to see how much the local independent Mercedes repair shop would charge to time the pump. I really hope they won't have to remove the pump (if it was off some teeth, for example) because that is really going to add to the bill and I think they would have a really hard time with the fuel hose and clamps.

I found out today that the fuel hose I installed a few months ago is melting at the ends by the hose clamps. That means that when I went to clamp down on the hose clamps that the hose would keep squishing out like clay and then the clamp would slide off. I had to replace much of it. It is supposed to be biodiesel-compatible hose. The lining seems to be compatible, but the outer hose is not!

Now I am REALLY not looking forward to fixing the engine oil leaks.

[Squiggle Dog]

Originally Posted by Diesel911

The only instrctions I have are fore ao 615 Engine but they appear to be the same.
You turn the Fuel Injection Pump Drive Gear clockwise until the flat/missing tooth or teeth lines up with the marke on the Fuel Injection Pump Bearing Flange (at about 11 O'clock).
Because it is under Fuel Injection Pump Camshaf is under spring tension they want you to put a little counter clockwise turn and let the spring pressure roll it back counter clockwise 2 teeth. That relieves the spring tension.

At that point with the Crankshaft timing marks at 47degrees BTDC on the Compression Stroke you stick the Fuel Injection Pump into the Engine but stick the Pump in so that the Slots where the Bolts or studs that hold down the Fuel Injection Pump are centered in the Slots (so you are able to rotate the Fuel Injection Pump either way).
Install the Bolts or nuts that hold the Fuel Inection Pump to the Block.

I stuck the pump in with the marks lined up and at 47 BTDC. Maybe I am off a couple of teeth, then, since I didn't turn the collar back two teeth? I really hope I don't have to pull the pump out again. I might try drip timing again to see where the drips stop so I know how far off I am.

[Diesel911]

Sorry about your grief on this job.

You might rest up and try timing again.
Since it hard to turn the IP with the Hard Lines on during the Drip Timing they are better off removed.

I also think it is best to have someone else pump on the Hand Primer to keep the Fuel Supply Pressure even; while you Rotate the Fuel Injection Pump and count the Drips is extemely helpful.

When I did mine I found a safe place to us my large Channel Locks to grab onto the Fuel Injection Pump. This gave me a lot of leverage and allowed me to tap/bump the handel and rotate the Fuel Injection Pump tiny amounts.

It might be that the Fuel Injection Shop that did the Fuel Injection Pump might also do the timing.

[Squiggle Dog]

Originally Posted by Diesel911

Sorry about your grief on this job.

You might rest up and try timing again.
Since it hard to turn the IP with the Hard Lines on during the Drip Timing they are better off removed.

I also think it is best to have someone else pump on the Hand Primer to keep the Fuel Supply Pressure even; while you Rotate the Fuel Injection Pump and count the Drips is extemely helpful.

When I did mine I found a safe place to us my large Channel Locks to grab onto the Fuel Injection Pump. This gave me a lot of leverage and allowed me to tap/bump the handel and rotate the Fuel Injection Pump tiny amounts.

It might be that the Fuel Injection Shop that did the Fuel Injection Pump might also do the timing.

Yes, not having the lines in place would make the process easier. I had assumed that they needed to be in place. I mailed the pump and injectors out of state so the option of having them do the timing is out.

[Diesel911]

The reason you are sticking the IP in at 47 degree BTDC is because the teeth are supposed to be backed off.
Otherwise you would be sticking the IP in at something like 26-27 Degrees BTDC. So it looks like one tooth must be worth 10 degrees on the Crank Damper Degree marks.

[Squiggle Dog]

Today I pulled out the first pump delivery valve and attached the drip tool. I rotated the engine many, many times with a ratchet while pumping the primer pump. I probably went through a gallon of fuel and I could not find a spot where it would stop streaming. I noticed that between 36 and 19 degrees BTDC that the fuel would thin out.

Then I removed the starter knob cable and pushed the lever on the pump back to starting position a couple of times. I had a hard time understanding the factory service manual's meaning when referencing "all the way to stop position", not sure if it meant "non running position", "starting position", or what. I rotated the engine again and then noticed the fuel started dripping and then upon slight further movement the drips would stop! I then knew where the start delivery position was.

The delivery was advanced quite a bit (about 40 degrees) and rotating the pump all the way toward the engine wasn't enough to get it to 26. I must have had the pump off a few teeth when installing it, or the pump didn't "spring back 2 teeth", or whatever.

I had to remove and refit the pump many times. I thought I would have to remove the fuel hose but I detached the main fuel filter housing and this allowed movement of the hose so I could pull out the pump enough to rotate and reinsert it.

Rotating the pump as far as it would go, removing it, then refitting it was getting to be too difficult so instead I removed the pump then rotated the engine to 26 degrees BTDC and inserted the pump (I could see that it was in start delivery position when it was out). It was too far retarded so I removed the pump, set the engine at 40 degrees BTDC, then reinserted the pump. It was very close and I dialed it in to exactly 26 degrees BTDC with the studs almost perfectly centered in the slots.

Now, the bad news; the new pump to engine paper gasket did not hold up and I need to order a new one. If I am fortunate I can remove the pump, insert the new gasket, and have the adjustment be close enough to fine tune. I am really hoping that this works out. It's definitely a learning experience and sometimes the manuals are too difficult to understand.

Now I am relaxing and enjoying Dal Tadka and Aloo Mutter with brown Basmati rice. International food is great. And thanks for the advice, everyone!

[Squiggle Dog]

I had the valve cover off at one point and out of curiosity I decided to check the chain stretch. I moved the engine to TDC and looked at the two marks on the cam to see if they lined up. They were off a bit, but instead of the mark on the pulley being behind the mark on the cam (if it had chain stretch), the mark on the pulley was ahead of the mark on the cam, as if it was ahead 1 one tooth.

A simple way of explaining it, is it's as if there is a good deal of chain shrink instead of stretch. When the marks would line up I believe the pointer said the engine was at 9 degrees BTDC. If the chain was stretched, wouldn't it show an ATDC reading (9 ATDC), not BTDC? Weird...

[Squiggle Dog]

Yesterday morning I called my local Mercedes Auto Service shop and had them order a new injection pump gasket and they had it that afternoon! They also had a 600 limo in there, too. Wow.

Since I had the first delivery valve out I put the copper sealing washer in my wallet so I could match it up with a new one since they are supposed to be replaced each time the valve is opened up.

Today after work I took my silver bunny bank to Fred Meyer to use the CoinStar machine. I knew I had a nickel in my wallet so as I was walking toward the store I opened the change pocket in my wallet and the crush washer fell out. I set my bunny bank on the side of the building and hunched down to look for the washer. About ten minutes went by and then this lady reached over and picked up my bank. I said, "That's my bank" and she replied, "No, I'm taking it into the store" so I had to follow her into the store and listen to the lady tell the customer service representative how she found the bank outside of the store and "this young man got really itchy about it and tried to get it". I got it back, at least, but never did find the sealing washer.

When I got home I unbolted and moved the pump then installed the new gasket. It must have jumped a tooth because when I put it back in it was too far retarded. I pulled the pump back out and set the timing to 41 degrees BTDC, reinserted the pump, then got it adjusted exactly at 26 degrees BTDC. I did two more rotations of the engine to check and it was still at 26 degrees BTDC. The factory service manual says to insert the pump at 47 BTDC but I have found that 41 BTDC worked best. The studs were centered in the holes as well.

I opened up the second delivery valve and took it with me to CarQuest to get replacement sealing washers, some viton O-rings, and a cotter pin. They didn't have anything except for the cotter pin, but they gave it to me for free.

Then I went to Williams Oil Filter Service Company. They didn't have copper sealing washers the right size but they had viton O-rings that would hold up to the biodiesel. I also got some great "Thickster" nitrile gloves there.

The next place I tried was Mercedes Auto Service again and they had the copper sealing washers I needed. And for free, how nice! That made my day.

I got back and installed the new copper sealing washers and viton O-rings in the injection pump delivery valves. I hooked up the rest of the pump parts, bled the fuel system, then the car started right up! It smoked white smoke for a while until I got in and drove away.

There is not more surging at idle. The smoke cleared away as I drove. The car has lots of power again (in fact, a bit more than it used to have). There was no smoke at all on the freeway. When I got back into traffic there seemed to be a bit of white smoke at idle from time to time. It's an improvement and I can drive my car again, so I am VERY excited.

I am hoping that the next time I drive the car a few thousand feet above sea level that it won't smoke black smoke and lose power like it did before. I don't know if these cars have to be adjusted for changes in altitude?

Now that I have experience replacing an injection pump it would not be difficult to do anymore. Learning how to do it the first time is very, very hard and the factory service manual really had me lost. I almost gave up, too!

This car is only 4 shock absorbers, 2 engine mounts, a radiator recore, and some engine oil leak fixing away from being in excellent mechanical condition. I drove it to Utah and back over a month ago and now I am really confident in its reliability.