In reply to Glutton4pain :
Ah, so that's really interesting: It looks like they only sold those as Dodges and Freightliners until 2010 when they went to BlueTEC. I just assumed that they also sold them as M-B vehicles at the same time. Interestingly, if I go find a VIN from a 2008 Dodge Sprinter 2500 and plug it in to WIS, it decodes properly and brings up the service information. No idea if Xentry would recognize it, but it wouldn't surprise me.
Looks like straight out the front with the transmission attached is the "official" way to do it. They do at least call for the A/C system to be set to the side and not opened up, so that'll save some time and money. Only because I'm curious: Why not new main bearings and thrust washers?
Setting the timing isn't all that difficult, it's just a bit fiddly. You're installing a new timing chain, so that's going to eliminate a large source of frustration - I found that while mine was "in spec", it was stretched just enough to make it incredibly difficult to get everything to line up. I put my harmonic dampener on so that I could copy the timing mark from that pulley to the crank itself and then from there to the block. Take out the chain guide that the tensioner pushes against as well as the tensioner, of course. Make sure your engine is sitting level and then clock your balance shaft such that the little nick is straight up:
(that's the little nick - the picture and the engine were both a little off-level, but that's straight up and down relative to the engine itself)
Run your chain through and drop the cams in. I think I took the sprocket off the right side, got it around the chain, and then attached it to the cam. What's a little weird is that the chain drives the right intake cam and the left exhaust cam. The good news is that all the valves on the left side are closed at #1TDC so there's nothing pushing that side. On the right side, though, you do have a bit of a challenge to get the cams in place. That's where the "special tool" comes in to play:
I made my own out of composite decking of all things, but basically you're looking for something that has half-circles cut out that are approximately the same diameter as the camshaft journals and spaced to be able to land on both of them. Whatever you make it out of needs to be soft enough that it won't score or scratch the cam, which is why I went with plastic. You can do it without that - I believe FJ40Jim just used the little hold down straps - but I found it almost impossible to get the cam in place without them.
There are little dots cut in to the sprockets on each side. For the right side, the dot on the bottom of the tooth valley for the exhaust cam should be level with the surface of the head while the dot on the tip of the tooth should match up with the dot in the tooth valley on the intake cam:
I don't have a good picture of the other side, unfortunately, but this is the almost-helpful image from WIS:
The official install instruction is "Do not mix up camshafts. Markings (2) on camshafts must be aligned with each other and markings (3) on camshafts, seen in the direction of travel, must be aligned on the left side to the cylinder head upper edge".
The cams on the right side are going to want to move. I used some small c-clamps to put a bit of aluminum angle between the exhaust cam sprocket teeth and the head to prevent the right side from moving on me while I threaded the chain around. I also used a vice-grips on the cam to get it into place and to hold it steady. Once the chain is all the way around, you can slide the tensioning guide in and pop the tensioner in. Just make sure any slack in the chain is to the left of the cam sprocket as you're facing the front of the engine. Once the tensioner is in, you can put the cam straps on, torque them down, and pull off the special tool and whatver you used to keep the right side from turning.