That's the only safe way to do it at this point. You'll only damage the screw further if you can't see it.

Questions on 300SDL IP?
 

I may not tackle this job but just want to ask a dump question.

I failed miserably to remove the last screw in the far RH corner. I put a small tray underneath the IP with some rag and it seems to be collecting all the oil. However, I am considering taking out the IP as I bought the o-ring and I may as well put it to good use.

Say, if I mark the IP pump relative to the engine block and re-install it in the SAME place, do I need to set the timing again? Can I screw up? I have done gas engine timing but I am not sure whether I can handle the 603 engine.

Any advice is welcome.

As long as the IP is locked when you remove it and remains locked until you install it, there's no need to mark the block. Mind that you install the IP such that the bolts are in the middle of their slots so you have the maximum range of adjustment in both directions.

[edit] You'll reduce the number of variables if the timer remains engaged with the timing chain.

You can eyeball IP timing easily with an IP lock. It's not more difficult that timing a gasser distributor, just a ton heavier :) You can rent an A-B timing light in the tool rental forum which you might as well do to remove the doubt.

Sixto
87 300D

What do you mean by locking it? I am a novice on diesel engine and IP.

Thanks Sixto.

On the driver side of the IP, there's a service port capped by a plug that takes a 17mm wrench. When you remove the plug, a couple of teaspoons of engine oil will drip out, and it should look something like this -

http://www.w124performance.com/image...__RIV_tang.jpg

The flat screwdriverlike tip you see will be centered in the port when the IP is at the reference position which corresponds to a crank pulley position of 14* ATDC #1. That's where it would have been set at the factory. It will shift because of chain wear, replacing the head and gasket, etc.

The locking tool looks like this -

http://www.w124performance.com/image..._lock_tool.jpg

The lock threads in place of the plug and the slot at the far end engages the tang visible through the port. With the lock in place, the IP driveshaft cannot move relative the IP case so IP timing is preserved when removing/installing the IP.

[edit] Pictures from the gsxr collection.

Sixto
87 300D

Great pictures, thanks

I had the same leak from the bottom plate on my son's 87 300SDL. New seal from the dealer was $13. We had couldn't get the torx screws out so we just removed the IP put in a new bottom plate seal and all new o-rings at the same time. Popped it back in and fired it up. No leaks, no problems.
We wasted an entire day trying to get those torx screws out without removing the IP. Somebody had striped a head before us. Way less trouble to just pull the IP and 'git-er-done'.

W126 Diesel Injection Pump bottom seal replacement
 

I just completed this task on a 1987 300SDL and YES, it can be done without removing the IP (injection pump) from the vehicle. If I must stress ONE point, it is PATIENCE!

You DO NOT want to trash the Torx (T-30) heads of the six (6) screws (M6-1.0 pitch) x 12mm length holding the bottom cover in place.
My tools of choice were a 1/4" socket driver, an assortment of 1/4" diver extensions, a T-30 Torx driver bit, a flexible 1/4" driver extension and a (Sears Craftsman) 1/4" x 1/4" flexible socket. The T-30 Torx bit inserted into the 1/4" flex socket just barely yielded enough room to get a sufficient purchase (bite) on the Torx head screws to loosen them. As one member suggested in this thread, cutting down (shortening) the Torx driver bit will increase your ability to get a good grip on the screw heads. Since driver bits are usually made of hardened tool steel, it is usually necessary to grind the bit down with a grinder.

I found it helpful to remove the clamping bracket which supports the two hard lines to and from the oil cooler. This gives you a bit more room to maneuver in.

Make sure the Torx head recesses are clean and free of dirt so the driver bit will seat to the bottom of the recess. I used spray brake cleaner with an extension nozzle, a tooth brush and q-tips to get them squeaky clean!

Take your time! Take your time! Take your time! Be sure to have a GOOD grip on the screw head before you attempt to loosen it. BTW, this is not a real messy job if you do it after an oil change and before restarting the vehicle. The amount of remaining oil in the injection pump is not that much.

Once you have all 6 (six) screws loosened, it is not difficult to remove them. Clean the bottom of the injection pump thoroughly and the sheet metal cover as well. You are now ready to install the cover with a new seal ring (A 004 997 46 40). Usually, one wets (lubricates) the new seal ring with a bit of fluid (oil). However, doing so in this case will cause the new seal (i.e. big square cross-section o-ring) to slip off the cover or twist before you can snug the cover in place. I opted to fit the new seal dry, though I did consider a few drops of super glue to hold it in place on the cover plate.

If you are suspect about the condition of the screws you removed I would NOT waste time to visit the dealer in an attempt to get new ones. Rather, find a local fuel injection pump re-builder, one that handles Bosch injection pumps; he will have them and should only set you back about $8. Other alternatives are to use socket head hex screws (M6 x 1.0 x 12mm - 5mm allen wrench) or even better, flange screws/bolts (same M6 x 1.0 x 12mm - 10mm flexible socket driver). Just be certain the screws of your choice are at least grade 8.8 (minimum). I purchased new Torx head screws but opted to use flange bolts because of the larger bearing area of the flange head. I purchased a Sears Craftsman 1/4" drive x 10mm flexible socket driver for this purpose.

There is enough room under and around the injection pump so that you should be able to fit the cover and hold it in place while you install two (2) screws by hand to hold it in place. Then it's under the car to install the remaining screws and snug them down EVENLY. Put a rag under the injection pump (just in case), fire the beast up and check for leaks.
Hopefully, you are good to go for another 23 years.

Update on the leak.
 

This job has been dormant for a year. I just put a rag under it to soak up the oil. Managed to remove the last screw and replaced the seal. To remove the last screw, I used a saw blade and cut a slot on the bolt head. It was not easy as the access is difficult since the IP was in situ. I then used a flat blade bit to remove the bolt. So it is possible to replace seal without removing the IP but you just have to be careful.