Timing chain related - Page 3 - PeachParts Mercedes-Benz Forum

barry123400 · #31 09-20-2006, 07:11 PM

I would if it met two criteria. The rod extension past the flange must be very simular when extended. Also if it uses gaskets to seal against the block or an oil ring. That is one varience in listed types. The holes for supply must be the same and probably are. Pretty sure someone that has done this if possible might mention something. Remember the 616 and 617 engines are different castings but for all practical purposes might be identical in that area. Someone mentioned that tensioner operation is simular to a hydralic lifter and I thought that was a good observation. I have also succesfully reactavated old hard to get lifters by taking them apart and cleaning them out. Worked quite often on those old early large buick straight eight engines. Just gummed up basically. Really though the older design is basically okay as well since total failure of the tensioner is not all that common. Plus the early 60s Gas mercedes I worked on had the same design tensioners with few problems as well.

gregszustak · #32 09-23-2006, 11:54 AM

Fianlly got back to it. Too much rain and I ended up buying a tarp.

Anyway, measured chain stretch, seemed about 6 degrees.

Pushed in guide by tensioner and was able to push it somewhat with my hand (towards passenger side, providing less tension). Not sure how much pressure the spring is supposed to provide.

Pushed the other way to give more tension on the chain. Noticed an improvement (small) but I was still able to lift the chain slightly off the cam sprocket.

I will be replacing chain and tensioner.

Brian Carlton · #33 09-23-2006, 12:00 PM

Quote:

Originally Posted by gregszustak

Fianlly got back to it. Too much rain and I ended up buying a tarp.

Anyway, measured chain stretch, seemed about 6 degrees.

Pushed in guide by tensioner and was able to push it somewhat with my hand (towards passenger side, providing less tension). Not sure how much pressure the spring is supposed to provide.

Pushed the other way to give more tension on the chain. Noticed an improvement (small) but I was still able to lift the chain slightly off the cam sprocket.

I will be replacing chain and tensioner.

Yep, six is a bit much. If you do replace the chain, make sure you thoroughly understand the process and, additionally ensure that you've got two friends to help you. It's possible to do it with less assistance, but, the risk of failure increases exponentially if you go that way.

gregszustak · #34 09-23-2006, 11:04 PM

Got the Haynes, did a lot of reading on this site, reading from diesel giant.

One helper, bungee cords in case the help sneezes, couple vice grips, about 50 rags from work, wire to hold the chain if I need a break and chain press rental.

Think I'm all set. Appreciate everyones input.

Ken300D · #35 09-24-2006, 11:43 AM

My 240D has something of the startup "rattle of death" as I've seen it called here. There is a disturbing clashing rattle when starting the car that goes away as soon as oil pressure builds up. I wonder if it is the timing chain tensioner gone bad?

My initial thoughts were this rattle was a belt-driven peripheral, most likely the power steering pump. But recently I had all the belts off and the car did the same.

This thread has given me another idea. Does your car have an engine rattle on startup?

Ken300D

gregszustak · #36 09-24-2006, 12:04 PM

I'm new to diesels, not sure what noise is supposed to be there and which aren't. The most disturbing thing that caught my eye was chain marks on the inside of the cam cover.
One of the rattles I was able to detect were caused by broken air cleaner mounts. Used an epoxy and let it dry overnight.

Ken300D · #37 10-09-2006, 11:46 AM

Well, I took on the job of rolling in a new chain on my 1981 240D this weekend. I found the tensioner to be non-ratcheting, and the spring still functional. This was after I took the tensioner off for examination. My estimation at this point is that there was nothing extremely wrong with the tensioner. There were no chain marks inside the valve cover.

However, without the tensioner I found the chain to be quite loose. I could pick up the slack side of the chain and slide the slack a full tooth over. Ah ha! Bad chain I thought.

I decided to roll the engine over a few times in this condition and see how the chain elongation would measure against the marks. Bad idea. Two times I noticed a kind of click where the crank continued to turn but the cam did not. On the third click the engine jammed shortly after. At this point I realized the chain obviously jumped three teeth. Nothing to do but turn the crank backwards and cause a slip in the other direction. No problem doing this and I slipped the crank one tooth backwards. Had I been thinking properly I would have gone ahead and slipped another two teeth and been back in the proper position.

But, at this point I put the tensioner back in and that took up the slack. Rolled the new chain in by myself with no problems using the many-many zip tie method. I have the link pressed on enough to hold the chain for now.

So, I rolled the engine over a few times to see how far off the marks are. Did not appear to be even close. Now I think maybe the crank's harmonic balancer has slipped around some.

My plan now is to get a helper to slack the chain just enough to slip two more teeth on the crank and expect that to return the engine to proper timing. But I'd like to confirm it by TDC. Do I have to pull the #1 injector and prechamber to observe the piston?

Also, with the tensioner out, the new chain is considerably slack too, just not as much as the old chain.

My advice on rolling in chains on the 240D engines with non-ratcheting tensioners is to leave the tensioner in while doing the roll in.

Ken300D

Stevo · #38 10-09-2006, 01:16 PM

Quote:

Originally Posted by Ken300D

Now I think maybe the crank's harmonic balancer has slipped around some.

My plan now is to get a helper to slack the chain just enough to slip two more teeth on the crank and expect that to return the engine to proper timing. But I'd like to confirm it by TDC. Do I have to pull the #1 injector and prechamber to observe the piston?

Also, with the tensioner out, the new chain is considerably slack too, just not as much as the old chain.

My advice on rolling in chains on the 240D engines with non-ratcheting tensioners is to leave the tensioner in while doing the roll in.

Ken300D

How do you figure the "crank's harmonic balancer has slipped around some."? I dont see how that could happen. I think at this point I would get the cam and crank timed right by "adjusting " the chain then I think you are going to have to time it as I'm not sure where the IP is by now. "We learn by doing"

Ken300D · #39 10-09-2006, 02:41 PM

It is my understanding from reading here in the forum that the bolts holding the harmonic balancer can shear off. Then the thing can slide around depending on how tightly the big crank bolt is holding on.

Just speculation on my part.

It just occurred to me that slipping two teeth at the crank sprocket is equal to slipping one tooth at the camshaft, due to the 2:1 ratio of the sprocket sizes. Since I am fairly sure there was slippage at the crank - this explains why the engine will still rotate without valve interference.

So I have my strategy on how to get things all back in correct time - but I want to have a measurement to verify it, and at this point I don't trust the alignment of the markings on the balancer.

Ken300D

Stevo · #40 10-09-2006, 05:42 PM

[QUOTE=Ken300D;1298925]It is my understanding from reading here in the forum that the bolts holding the harmonic balancer can shear off. Then the thing can slide around depending on how tightly the big crank bolt is holding on.

Just speculation on my part.

Hummm.. Well I sure wouldn't bet any money and stranger things have happened but I would be real surprised if the balancer could be "off" with out being... all the way off

As I remember you can be one tooth off and still rotate the eng. It would be hard to find TDC, not as easy as taking a spark plug out

Good luck, I'll be interested to see what the other folks say about your balancer.

leathermang · #41 10-10-2006, 12:10 AM

"My 240D has something of the startup "rattle of death" as I've seen it called here. "--Ken300D

That is talked about in the 616 manual... Check your oil pressure relief valve on the backside of the oil pump.. they keep changing the pressure they operated at ( at least three different styles used )...and they mentioned that they can fall out .... If I ever have my pan off I will put a new one of the last style they tried.... mine has the same sound you describe... Greg

Ken300D · #42 10-10-2006, 01:39 PM

Can you get to this relief valve with just the lower oil pan taken off?

Ken300D

Stevo · #43 10-10-2006, 06:27 PM

I know you can take the pump out with the lower pan off.