PLEASE HELP!! In middle of timing chain R&R - PeachParts Mercedes-Benz Forum

BigMikeT57 · #1 04-26-2002, 11:12 PM

Started job tonight. Replaced the 3 guides. Will roll in chain tommorow.
Can the tensioner guide be replaced w/o removing the head?
Have read every post about timing chain R&R and no one mentions this guide.
I pulled the allen plug where I thought the pivot pin should be.
I could'nt seem to feel anything inside that would be the pin.

Also, do I install the new tensioner before or after rolling in the new chain?

Thanks in advance for your help.

MikeTangas · #2 04-27-2002, 12:52 AM

I didn't worry about the tensioner guide since it's in the lower part of the block. I loosened the old tensioner, but didn't remove it, to change the upper guides, then left it loose while rolling in the new chain. By loose, I mean the bolts were backed out about 1/2 way, that allowed just enough to slip off the left cam sprocket.

Upon finishing the new chain roll in, it appeared the chain was one link short, removing the old tensioner allowed the chain ends to meet. Once both ends were connected I installed the new tensioner with a new gasket. It took every bit of oomph I could muster to compress the new tensioner AND hold it in place while starting the bolts. This might take a couple tries as it is kinda tricky getting the tensioner rod to mate just right on the guide pad - looking down into the crankcase once the old tensioner is out you'll see what I mean.

Once the chain is all the way in, connected and new tensioner in place, be sure to roll the engine through two complete revolutions yet again. On a side note, I found it took something like 6 revolutions to bring the new master link back to the same position it was when installed. Remember this chain is 6 feet long.

Hope this helps.

Paul · #3 04-27-2002, 01:58 AM

no the head doesn't need to be removed to replace the tensioner rail. underneath the allen plug is a hollow pivot pin. if you insert an easy out or anything that will in the inside firmly it will slide right out. i would also replace the tensioner as this wil make the job complete...good luck..paul

BigMikeT57 · #4 04-27-2002, 08:03 AM

Thank you!!

I'm on the job.

#5 04-27-2002, 08:32 AM

I agree that you should replace the tensioner rail. It is usually pretty warn. When you go to put the hollow pin back in, you will probably find it difficult to line up. Use a smaller diameter bolt to line it up first. Then without moving the rail try to put in the pin. Don't get frustrated if it takes you several tries. Eventually it will line up.
Use Mike Tangas's excellent suggestion and go and buy a bag of 100 plastic ties at Home Depot. Use them to attach the chains(old and new) to the cam gear. It works great. It keeps the cam from jumping. You can only roll in a few inches at a time. As soon as the chain STARTS to come off the gear, STOP. Keep removing the old ties and replace them with new ones. It only takes about 45 min to an hour for this job. Take your time, so you don't mess up.
Good luck and if you run into trouble come back and ask for help if you need it. That's how I was able to do this myself thanks to this wonderful forum.
Woody

#6 04-27-2002, 08:39 AM

After you roll in the new chain remove the tensioner, install the new rail and then the new tensioner. Suggest you dip the tensioner in a can of oil and work it to get oil pressure. Before you start the motor, you will have naturally hand cranked the motor through several complete revolutions to make sure everything is okay. Still, I would pull the coil wire and get oil pressure before starting for the first time.
Woody

engatwork · #7 04-27-2002, 11:37 AM

During the recent head job on the 300D I used tye wraps to "mark" the chain and the sprocket and used a bungee strap to maintain tension. When I roll one in I aways have tye wraps maintaining the chain to cam sprocket relationship but pulling the head requires removal of the cam sprocket. Using the bungee strap (the chain was not tye wrapped together - just a tye wrap at the pin location for installation on the camshaft. This allowed me to lay out the chain towards both sides of the car as needed.
The bungee cord to the chain allowed easier installation of the head too.

Paul · #8 04-27-2002, 07:14 PM

when removing the head on the diesels you can just remove the cam gear and just let the chain drop in the block and just fish it back out after the head is on. it's a piece of cake as long as you don't split the chain or move the crank...paul

Paul · #9 04-27-2002, 07:36 PM

btw there is a tool that mounts on the head that is sort of a sprocket fender that keeps the chain tight while rolling on the new one. it's a one man job and takes about two minutes to roll the new one in and you never have to worry about jumping timing while the rockers are still in....paul