Chain Replacement Tool
 

I'm starting to gear up to replace the timing chain on my 617. I decided to build a guide tool to facilitate threading in the new chain and removing the old one.

Here is the thought process and the fabrication steps in building the tool.

I first fabbed up a base plate for the tool, tieing in to the bolt for the front lift point as well as an unused bolt hole lower and to the left. In addition I have a bolt in the pin for the upper chain guide to provide a third reference point.

http://www.peachparts.com/shopforum/...1&d=1401153898

Next, I fabricated the front support piece. The center hole rides against the cam gear for support and centering. I also clearanced for the chain guide bolt to get the right alignment.

http://www.peachparts.com/shopforum/...1&d=1401153908

I next cut and carefully bent the chain guide to fit closely against the chain.

http://www.peachparts.com/shopforum/...1&d=1401153920

Then just welded things up and cut the hole for the chain access. Even though the rig is quite sturdy, I added a rear support member that ties into the valve cover bolt on the drivers side.

http://www.peachparts.com/shopforum/...1&d=1401153937

Here's another view.

http://www.peachparts.com/shopforum/...1&d=1401153947

The final step will be to powercoat the tool.

This should make the job pretty quick and easy and I should be able to do it by myself.

Nice! What's the theory of operation? Keeps chain pressed against cam sprocket at all times?

Very important to keep the chain against the cam gear. The jig really looks awesome, but to be quite honest; my daughter and I rolled one in 3 weeks ago on my 85 300d using zip ties. Real simple, add a zip tie, turn crank add zip tie, remove zip tie. Chain was rolled in and ready for crimp in about 15 minutes.

Do you have a crimp tool?

Also very important to clean area where chain tensioner and thermostat housing will mount. I used a die grinder with a scotch brite wheel. When ordering gaskets, order 2 just in case there is a leak; better to have on hand than to have to wait a week for parts (ask how I know).

very kewl
 

Okay, I'm impressed! Looks like it'll beat my ol' tried 'n true "zip tie" method! So what are your thoughts here, make these, go into production, offer 'em up for sale, maybe per order basis? Or just tease all the rest of us, whetin' our appetites? Rent the 'one off'? Inquiring minds wanna know!

Precisely. If you read some of the how-to threads, people are using two people and tie wraps, vice grips and all other manner of devices to keep the chain intact and snug on the cam gear. This tool makes it virtually impossible to screw up the job by having the chain jump a tooth.

Here's the one whunter made. I wanted to try a different design.

http://www.peachparts.com/shopforum/...ga33460005.jpg

The main thing is just to share my thoughts and design so anyone with the desire and tools can make their own...also to get feedback and discussion toward making tool fabrication easier and better. It's untested as of yet, so assuming it works well, I might make it available in the tool sharing site.

I learn so much from others that share their knowledge on the forum, just want to share what I'm learning/doing relative to keeping these old diesels on the road.

Very nice!

My mechanic used this tool when he replaced the chain in my 300D
https://farm9.staticflickr.com/8195/...c99d63e6_z.jpg
https://farm9.staticflickr.com/8325/...5122b77a_z.jpg

There is a provision to mount to one of the head bolt holes, but he opted not to remove it for obvious reasons. He simply used a vice (also visible in the images) to fasten this rear section.

https://farm9.staticflickr.com/8190/...316797ef_z.jpg

Nice, I wish I had gone with their design of the "link window"... it would have added a bit of strength on that side.

Are you sure your chain guides are still good?

In preference to something like this I'd just remove the rocker arms cut the chain and fiddle about to my heart's content!

It is nice to build tools but only if you have storage space for them or use them a lot

Patent Pending?

It also covers the problem of stuff dropping down the Timing Chain Tunnel and reduces the chance of particles from grinding or cutting off the Timing Chain from getting into the Engine.

I have not read the proceedure closely but can the Large Timing Chain Rail can be removed and replaced before you change the Timing Chain?
If it can be removed like that after you install the large Timign chain Tensioner Rail just don't put the Tensioner on till the New Chain is installed.

Question for anyone about if it is really needed to replace the 2 lower Timing Chain Rails; see diagram?

I think your "window" for accessing the chain is too small.

I actually purchased the official MB tool for replacing the timing chains on OM60X engines. It bolts to the head using two of the 10mm bolts from the valve cover. It has a very wide "window" which really only holds the chain to the sprocket at two places about 180 degrees apart. Works just fine.

I estimated the window based on other tools. It appears that 5 link pins might be the sweet spot, based on the configuration of the "official" tool.

http://www.peachparts.com/shopforum/...1&d=1401217793

If it needs to be a bit wider, a quick swipe with a cutting wheel on an angle grinder will do the job...except it will screw up the powdercoat. I'll know soon enough.

Here are the pieces coming out of my powercoating oven.

http://www.peachparts.com/shopforum/...1&d=1401219844

And here's the finished product.

http://www.peachparts.com/shopforum/...1&d=1401219967

Before going to powercoat, I decided to add a stiffener to the vertical to provide some additional strength to the chain guide.

http://www.peachparts.com/shopforum/...1&d=1401220086

I don't know how much pressure is being applied in the pulling direction on the chain, so this is just cheap insurance to make sure I've got enough stiffness to prevent the chain from jumping a tooth.

If I remember correctly you'd have to remove the tensioner and the camshaft cog to get the largest rail out. The bottom ones on the right of your picture require removal of the timing device (and vacuum pump of course) and I think it is prudent to remove the sump too to catch / find anything you might drop whilst doing the job!