I really appreciated reading everybody's posts regarding their repairs when their serpentine belt idler pulley would break off the timing cover. After suffering the same fate, I've put this advice to use and purchased a used timing cover (part # 603-015-02-01) to replace my old cover (part # 603-015-00-01). I managed to disassemble everything over a few weekends with the engine in the car.

I have a few remaining questions that I'd like to ask for your help about:

1. I'm not planning to use black silicone RTV sealant, The Right Stuff, or Hylomar since others had reported leaks after using these. Instead, I'm going to order a 90g tube of Mercedes-Benz 002-989-45-20-M22 Clear RTV Sealing Compound to apply to the mating face of the timing cover as well as the vacuum pump. Should I apply this clear sealer also to the head gasket where I removed the 2-3 bolts on the top side of the timing cover? Should I apply it to the oil pan gasket where I backed out the oil pan bolts and carefully slipped off the old timing cover (please refer to the oil sump photo)? If not, should I just wipe these gaskets dry and then reassemble everything?

2. Should I use a blue or red threadlocking compound on all of the timing cover bolts, pulleys, and oil pan bolts when I reassemble everything?

3. How do you remove the dipstick from the old timing cover so I can attach it to the new one?

4. The topmost bolt on the water pump broke off when I was removing the water pump. The broken screw is sitting flush where it screwed in to the engine (please refer to red arrow in the water pump photo). I want to ask how I can get this bolt out or if you think the new water pump will still seal with 1 bolt missing when I put a new gasket and water pump on.

5. When I removed the power steering reservoir and pulley, I noticed that the pulley when attached has some slight play (0.5mm - 1mm) when I pull in and out on it. Is this normal?

Thanks for suggestions to any of these questions.

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1: I used Hylomar. It never leaked. For all the other mating surfaces, I followed the FSM recommendations.
4: I do not think the new water pump will seal without all the bolts.
3: I don't remember, but it can not have been that hard because I don't remember it being a problem.
5: Not as far as I know.

I would rather change a head gasket then a timing cover.

__________________
Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO

Did you have the top of your block skimmed? The timing cover needs to be flush with the top of the block for the head gasket to seal properly. Best practice would be to have the cover and the block skimmed as a unit, as you can't be sure when mating parts from different engines. I'd worry more about that than what brand of sealant to use on the mating surfaces. See how closely they fit in this photo:

http://www.w124performance.com/images/OM602_head/block_surface2.jpg

If you mix and match parts, the fit isn't always so pretty.

The dipstick should come out with a little persuasion. Try a soft blow with a rubber hammer. Careful not to bend the end of the tube. There are no fasteners holding it in place.

Don't even think about putting the water pump back on without all the bolts. Now is the time to get that done. Make sure no metal shavings from the drilling get into your open pan below.

__________________
1991 350SDL 350k+ miles

Thanks everyone for your input.

I tried hitting the base of the oil dipstick with a plastic mallet but it didn't want to come out. I might try putting a little heat to it and see if it will free up since it's still on the old timing cover which I don't care about anymore.

I like the photo of your block surface. I'd do that if I had it out of the car, but at this point I'm going to try my luck at getting the timing cover to seal without taking the head off and just using the proper sealants. If it doesn't want to go in easily though, I know that the surfaces aren't similar. Crossing my fingers...

I'm going to try drilling and retapping the thread for the water pump since I can't get out the piece of thread that broke off. I'll do this after I reassemble the timing cover so the shavings won't get into the mix. I wish I knew where to order replacements for these bolts and also for the timing cover bolts because some of them are all chalky and corroded. If I can't find them online, maybe if I visit the local hardware store, they can find me a close replacement.

If it doesn't come free after heating before I kept pounding on it I'd cut it free with a Sawzall. That way I know the pipe itself isn't dinged or otherwise deformed and I'll be able to install it into the new cover without any of those problems. the old cover is scape metal so you're not losing anything and keeping the valuable part you need intact.

Take one of your old bolts and stop in at Fastenal. They can match it and get replacements.

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1991 350SDL 350k+ miles

I had to take out the three bolts indicated by the red arrows in order to remove the old timing cover. At some point, I had to rotate the crankshaft in order to remove the vacuum pump while it wasn't under load. I don't remember exactly, but these 3 bolts may have already been taken off when I rotated the crankshaft. Now that I'm reassembling the timing cover and everything, is it ok for me to just screw in these three bolts and call it good, or did I potentially mess anything up with the injection pump timing when I rotated the crankshaft?

I also made a mistake and tried reusing one of my old timing cover bolts. I screwed it into the location circled in green and it broke off. I'm not planning to take everything apart again in order to drill out this single bolt. It was far too frustrating to put it all back together, so I'm hoping it will still seal with all other bolts in place. I applied the orange Mercedes 001-989-89-20-10 sealant (as indicated in the photo) to the timing cover mating surface and where it touched both the head gasket and the oil pan gasket. I bought all new bolts from Fastenal and torqued everything else according to the FSM specifications.

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In the above picture, do I have to redo the injection pump timing after I remove the 3 bolts with the red arrows and turn the crank? I'm trying to screw them in now after replacing the timing cover, but the bolts don't seem to be grabbing onto anything. I think I may have turned the crank slightly after I had pulled these three bolts off and am wondering if it would have an effect on the injection pump timing.

As long as your chain didn't jump a tooth, and you didn't remove the bolts on the rear of the IP, your timing should be ok. Try wiggling the injection pump a little while you start the bolts. Those 3 bolts are what hold the injection pump tightly in place. The injection pump should not have moved when you removed those 3 bolts. There is also a reverse thread center bolt on the IP timing device (sprocket). You should not have hat to removed that either.

__________________
1991 350SDL 350k+ miles

I believe there are big square nuts that go on the ends of those bolts. If you did not capture them as you removed the bolts, then look on the floor, or on the bottom engine bay shroud, for them.

__________________
Greg
2012 S350 BlueTEC 4Matic
2007 ML 320 CDI
2007 Leisure Travel Serenity
2006 Sprinter 432k
2005 E320 CDI
1998 SLK230 (teal)
1998 SLK230 (silver)
1996 E300D 99k, 30k on WVO
Previous:
1983 240D, on WVO
1982 300D, on WVO
1983 300CD, on WVO
1986 300SDL 237k, 25k on WVO (Deerslayer)
1991 350SDL 249k, 56k on WVO - Retired to a car spa in Phoenix
1983 380 SEC w/603 diesel, 8k on WVO
1996 E300D 351k, 177k on WVO