We changed the timing chain in my 560sel in 1 1/2 hours with 2 people. All we did was remove the two valve covers. We wired up the chain going into the engine on the driver's side head to the bottom of the cam gear pulling it tight, and used a plastic tie to hold the chain to the top of the gear. We used a dremel and ground off the end of one link in the old chain on the outside of the driver's side cam gear just slightly below it, between the two tied down areas of the chain. With the chain now secured on both sides of the ground off link - (at this point we put rags into the oriface going into the engine around the chain - just in case we dropped the link pin - to catch it - instead of it disappearing into the engine)-we then punched the link out to separate the chain. We then took the new chain and using the connector link with it - attached it to the end of the old chain going into the engine. Remove the rags. Now the tricky part. One guy has to pull upward on the old chain going into the block to keep tension on it AT ALL TIMES with one hand. Then the second guy removes the wire holding the chain tight. The first guy uses his second hand to hold the old chain tightly into the teeth on the cam gear (remember- this is the driver's side cam gear) while the second guy cuts the plastic tie off. The second guy then uses a wrench to s-l-o-w-l-y- turn the engine clockwise to feed the new chain into the engine while the first guy keeps upward tension on the feeding chain and uses his fingers of his other hand to keep the chain firmly into the teeth of the cam gear. We slowly fed the chain in making sure the tension of the new chain feeding into the engine was tight and the old chain peeling off the top of the cam gear was always engaged with the teeth. When the first guy's hands got sore from maintaining the tension - the second guy wired up the chain going into the engine to the bottom of the gear and plastic tied the chain to the top of the cam gear - and both took a break - then repeated the process until the new chain was completely theaded through. Took about 45 minutes -including breaks - if I remember correctly. When the new chain appeared over the top of the cam gear - we plastic tied it to the gear to hold it into place. Then with one guy keeping tension on the chain going into the engine -that part of the chain is then wired to the bottom of the cam gear - Reinsert the rags around the chain going into the engine - in case you drop the connecting link clip - the other guy removes the clip from the connecting link and removes the old chain and reuses the link to attach both ends of the new chain. Remove the rags. Manually turn engine over two complete revolutions and check the timing marks on the cam gears and crank - Ours were still in alignment. Job done - take a break - have a stiff drink to success put valve covers back on with new crush washers and torque properly. If you then want to do the upper chain rails and tensioner - look for the thread by , either Mike Tangas or Thomaspin - one of them had a great detailed instruction with pix to make the job fairly easy. By changing the chain with the roll in method like we did - you save oodles of time in strip down of front of engine and re-assembly. Just to play safe though - before you start - paint a mark on the side of your old chain on one link - then turn the engine over by hand and count the links. Make sure your new chain has the same number of links. Since you cannot hold the old chain side by side to the new one to compare -I would do it - Lately some parts I get from suppliers have driven me nuts. One example is the new rad I put into my 560 - (the broken neck syndrome) As I compared the new rad to the old rad - the little connector for the hose going to the reservoir by the upper rad hose connector - looked funny - the hole in it was about 1/32" in diameter - not the 1/8" like the old rad. They forgot to ream it out after molding the top of the rad. Go figure - $550 CDN for a rad and they cannot even check that!I drilled it out and it works good.
Good luck - which ever method you use to install your new chain.