603 Removing Crankshaft Hub

[Hal Scripka]

I am recovering from the cracked head syndrome while I wait for Metric Motors in CA to build up a new one for me. I decided to replace everything above the pistons. The precambers were rusted into the head on three cylinders due to water injection. So all new valves, lifters and prechambers. Much to the dismay of my checking account, I decided to also replace the cam, injectors, glow plugs, and fuel lines. Meanwhile, I am fixing a few things here and there while I wait for the new head. I've replaced the vacuum pump (due to recent threads on the subject) and the aux water pump. The timing chain is 10,000 miles new and has no stretch. However, I noticed that the lower rail has small cracks or fractures in the plastic. It also has groves formed by the chain that are about 1mm deep. I would like to think I could let this go, because the procedure to change it looks somewhat complicated. I would appreciated any insight.

If I have to replace it, I have a few questions that I was hoping someone could answer. With the head off, I am afraid to move the crankshaft even a little. How can I remove the Hub bolt without moving the crank? I have searched the forums and there was mention of pulling the starter and doing something to freeze the crankshaft but it was not clear. Is this necessary, or is there an easier way. Should I wait until I have the head and timing chain back on to attempt this? The manual also talks about lifting the engine to gain access to the bottom bolts for the timing cover. Is this really necessary? I have the front bumber and radiator removed and it seems I have ready access to all the hex bolts. Has anyone had experience with this?

Also, I might as well replace the front crankshaft seal while I have the timing cover off. Is this something that can be accomplished without special tools? I read some threads which talked about R&R of the seal with the timing cover attached. Seems like it would even be easier with the timing cover off the engine. The seal does seat in the timing cover doesn't it?

I would appreciate any responses. It seems I am now in restoration mode of my newly acquired 1987 300SDL. I wouldn't even attempt it without this forum, although my wife still thinks I am nuts. Thanks.

[Hal Scripka]

I am still trying to decide if it is necessary to replace the lower timing chain guide rail on my 300sdl. I've included some pictures. There are small stress/heat fractures in the plastic. Is this just normal, or do I have to remove the timing cover and R&R? I would appreciate anyone experience?

Thanks

Hal Scripka
1984 190D 300,000
1987 300SDL 170,000

[TimFreeh]

Hal

It's hard to tell from your pictures but I've seen the small cracks/tracks in chain rails many times and I've ignored them. I don't know if there is an official inspection procedure but as long as the rail has more that half its original surface I just put it back together.

If you choose to replace the rail it looks like quite a bit of work according to my OM603 manual - I've never done the job but it would also appear the the lower half of the case shares a mating surface with the oil pan. It seems like there would be lots of opportunuties for leaks to develop, another reason to pass unless somebody has an official inspection procedure for the rail and can pronounce it dead.

It's OK to move the engine a couple of degrees, it won't loose time as long as the timing chain stays engaged with the IP drive and the crankshaft sprocket.

[Hal Scripka]

Thanks for the reply Tim. The thought of pulling the timing cover off and everything else that is required is somewhat intimidating. There is alot of plastic left so I think I'll just leave it alone. Appreciate the response.