OM61x timing. How do I get the back bolt loose?
 

I'm going to adjust the timing on my 617 and I can't get the rear bolt. That thing is deep down in there. Are people getting to it from below the car or just using a really long 13mm wrench?

Mine's about a 6" wrench and it won't reach. Curious if there is something I'm overlooking or if I just need to look for a different wrench?

I can't be of much help since I did not try this yet but I have read that it is even harder to get the nut and bolt back on; meaning loosen it but do not remove the nut and bolt.

what bolt?- on the crank?
if so there are 4 small ones on the front holding it on

http://i242.photobucket.com/albums/f...l911/ZXX1B.jpg
My car is on Jack Stands now so I went out and took this pic. It looks like from below is a good way to get at the bolt to turn it maybe with a 3/8 Breaker Bar to loosen it and a 3/8 ratchet or Gear Wrench if you want to remove it.
If there is a nut behind it and the bolt dose not want to loosen enough I believe I read that you need to get at the nut from between the Engine and the IP with a Open End or Combination Wrench. I also believe I read someone use one of those "stubby" short Combination Wrenches to hold the nut.
I believe ForcedInduction was one of the persons who commented on how to get at that bolt.

The other way to get a lot of room in that area might be to remove the Oil Cooler Lines and the bracket that hold them.

Thanks for the pic. I was out and picked up an extra long 13mm wrench from AutoZone. We'll see if that'll give me the extra clearance once the engine cools a little.

The car starts a little sputtery if I don't let the glow plugs go for a long time. I think the timing chain is stretched (250k). This car is old and rusty though so I'm not going to put any money into it. I'm going to just advance the timing a hair and see if that helps my cold starts. We'll see! It did on my 603 and quite a bit more power too. It's much peppier since I moved it up a little bit.

To get some idea of your Timing Chain stretch line up the timing mark behind the Chamshaft Drive Gear with the timing mark on the Camshaft Bearing Tower as accurately as you can. After that look down at the Crankshaft Damper degree marks and see what you can read there.
In this split pic the Timing Gear is on the Left side and a view of the Crankshaft Damper is on the Right hand side. I am showing about 2 degrees of Timing Chain stretch. (New it would have been at TDC; now it is 2 degrees past TDC.)
http://i242.photobucket.com/albums/f...esel911/Z3.jpg

I was also thinking on the labor involved to move and retime an IP and wondered that if a person had 4 degrees of Timing Chain stretch it might be much easier to just install a ofset key. This would restore the Camshaft Timing and also the IP timing (assuming no one retimed the IP before).

Got it done. I had to finagle with the wrench a bit and work around the oil cooler lines. But with some flipping sides of the wrench between each of the open end sides and the box end for a fraction of a turn at a time, I got it loose.

I advanced the timing just a little bit probably 1/16" to a little less than 1/8" by the bolt slots in the IP and it runs much better at startup. It also no longer has blue/gray smoke while idling upon start up. I think it could still handle a hair more advanced but that was a lot of work and I'm happy where it's at.

Perfect!

I did this as well this weekend. I found it was easiest to reach from between the cooler lines.

More power and a properly sounding engine, however I have more smoke under wot oddly enough.