1979 240D checking chain stretch - Page 6 - PeachParts Mercedes-Benz Forum

snapped_bolt · #76 06-16-2016, 04:53 PM

Just as I had suspected with the chain, it cam down with multiple mangleosis as I shut down the engine, and partially jammed down around the crankshaft sprocket.
I think this is about as close as you can get to actually breaking a chain without actual separation.

I have removed the timing device, all guide rails, pins. I zip tied the chain to the cam sprocket and had my wife rotate it and keep a little tension on the chain as I turned with a socket. We continued until the damaged area was on top where I could decide where to press out a link and attach the new chain.
I am replacing the timing device, but until that and a few other parts arrive I will install the old one just to run the chain around. I got the timing chain off the old sprocket with a slice of polyethylene water jug, it will slide between the chain and sprocket without leaving any tool marks. You will find I do go out of my way to avoid making any tool marks!
The lower inside chain guide has a lot of wear; the mate had scarce any.
The NEW tensioner rail (8 minutes run time?) has one thin scratch. Since I have all the new rails, they will be installed. All of the guide rails go in, with the exception of the lower outer upper pin so the timing device can be in/outstalled. (Outstalled is the opposite of installed? Not yet?)
I "deflated" the tensioner, I'll have to pull it out and re-prime it.
The new oil pump came in, I am encouraged that the box said "Made in Germany". The pump itself has GERMANY cast right into it; and in what seems to be an upgrade, the hard plastic uptake has been revised to a hard rubber, which will not shatter on impact of a curb or the like. It may deform, but it will still allow oil to pass freely.
So I'll "fake" the new chain in; remove the old timing device, install the replacement, check the marks on the cam and crank, install the IP, then the rocker arms.

Later,

snapped_bolt

snapped_bolt · #77 06-16-2016, 05:22 PM

gmog220d,
Which one?
The timing device rides on a steel bushing, and directly behind that is a bronze bushing. The steel bushing came out with a tug of the timing device, the bronze one retained with a steel washer, cut washer, and hex bolt. Pulls out with fingers. The bronze bushing rides on a larger diameter portion of the shaft, the Woodruff in front of the bushing is not in the way, don't pull it.
The thrust piece (on oil shaft) has a lock bolt on the side of the block; remove this, and pull the thrust piece up. With long nose pliers grab the oil pump shaft and pull up to remove. IP intermediate shaft pushes out the back of the block.

Question answered?

snapped_bolt

snapped_bolt · #78 06-16-2016, 05:23 PM

Rockers removed.

snapped_bolt

gmog220d · #79 06-16-2016, 07:16 PM

Quote:

Originally Posted by snapped_bolt

gmog220d,
Which one?

the bronze one retained with a steel washer, cut washer, and hex bolt. Pulls out with fingers. The bronze bushing rides on a larger diameter portion of the shaft, the Woodruff in front of the bushing is not in the way, don't pull it.

snapped_bolt

Yep. I was curious about the bronze bushing that's held in there by the washer, in the front of the block.

Does your '79 have the thrust washer between the bronze bushing and the steel timing device bushing?

leathermang · #80 06-16-2016, 07:22 PM

Quote:

Originally Posted by snapped_bolt

Rockers removed.....snapped_bolt

Somewhere you declared the piston tops and the valve un harmed.. can't find it ... but with the valves closed you could do a leak down test.... why do you think there was no contact in this accident...?

snapped_bolt · #81 06-16-2016, 08:06 PM

gmog220d,
I didn't see or hear a washer/shim/spacer fall when I pulled the timing device-but since someone used salvage yard parts on the "rebuild", if required, they may have left this part out, perhaps contributing to excessive end play. I f there is indeed supposed to be one, I will install one. I suppose I could take a spacer to a surface grinder and polish it to exactly .032"....

snapped_bolt

snapped_bolt · #82 06-16-2016, 08:08 PM

leathermang,

How would valves/pistons make contact with the chain yet unbroken?

snapped_bolt

leathermang · #83 06-16-2016, 08:32 PM

I thought you had some type of catastrophic stop... due to something in contact with the chain... ? no chance of movement of one or the other not still in sync with the other ?

Ok.. let me try this again... the relationship of the cam to the crankshaft , without the chain breaking , is only secure when the crank is providing the power to pull the chain... if that tension is not maintained then contact is possible between the valves and the piston top.

gmog220d · #84 06-16-2016, 09:49 PM

Quote:

Originally Posted by snapped_bolt

gmog220d,
I didn't see or hear a washer/shim/spacer fall when I pulled the timing device-but since someone used salvage yard parts on the "rebuild", if required, they may have left this part out, perhaps contributing to excessive end play. I f there is indeed supposed to be one, I will install one. I suppose I could take a spacer to a surface grinder and polish it to exactly .032"....

snapped_bolt

I was curious about what you found in there, or didn't. My FSM for 615, 616, and non-turbo 617 shows three types of timing device attachments, and in the "1st version" there's a thrust washer between the rear timing device bushing and the bronze bushing in the block. But that washer isn't shown in the diagrams for 2nd and 3rd versions. I'm curious to hear what more experienced members can say about how one goes about setting intermediate shaft end play.

snapped_bolt · #85 06-16-2016, 11:26 PM

One would assume that installing new parts would bring the end play within spec.
Easier said that done?
I also have pondered over this. I noticed the revisions as well as I searched part numbers. I am wondering about that spacer/shim, as to how thick it is. This engine appears to be "Version 2" based on the hub fastener being a bolt. I won't be starting this engine until the parts are there to remove the end play. I am posting my progress along with what it takes to get it done.

snapped_bolt

snapped_bolt · #86 06-16-2016, 11:44 PM

I had originally shut off the engine as I heard strange noises. It shut off normally, no drama. When I set up to do the 2 mm lift test, the chain wouldn't move but a little, and jammed. I removed the timing device, chain rails and tensioner, along with the rocker arms so I could roll the damaged part of the chain up top where I can break it and start installing a new chain. The chain was not broken until I used the chain breaker tonight. The camshaft does not contact the valves at this point, the new chain can be rolled into place without issue. Once riveted in place, I turn my attention to timing the cam to the crankshaft, then the IP sprocket, and install the guides.

How is this contact between valves/pistons supposed to happen without the chain breaking?

snapped_bolt

snapped_bolt · #87 06-17-2016, 11:31 AM

.... at least part of my failed timing chain master link is IWIS part 000 997 05 98, and this can be purchased on Ebay today! I thought Mercedes got over the snap-together timing chain for diesels...or perhaps IWIS didn't get the memo...or perhaps this is only intended to be a temporary link for rolling in a new timing chain.
Mine may be even more of a hybrid, as the master link itself is blued steel, and the master link plate itself is copper-washed.
Only one e-clip survived the perilous journey through the timing gears, dropping to the oil pan. Some of the missing parts were "processed" by tight clearances and the chain/sprockets themselves.
My FSM from 1980 shows the timing chain being installed with e-clips.

Perhaps some member has a later reference showing the change to crimped rivet chain installation?

Cheers!

snapped_bolt

gmog220d · #88 06-17-2016, 12:07 PM

Quote:

Originally Posted by snapped_bolt

One would assume that installing new parts would bring the end play within spec.
Easier said that done?
I also have pondered over this. I noticed the revisions as well as I searched part numbers. I am wondering about that spacer/shim, as to how thick it is. This engine appears to be "Version 2" based on the hub fastener being a bolt. I won't be starting this engine until the parts are there to remove the end play. I am posting my progress along with what it takes to get it done.

snapped_bolt

I'm guessing they did away with the separate thrust washer and modified the bushing in the timing device to take up the slack. That's what the diagrams seem to indicate. On a later version perhaps replacing those two bushings would put it in spec. But the FSM is a bit cryptic. The procedure for Removal and Installation of Injection Timer mentions checking that end play and it says to make adjustments to the washer to set end play, but no mention of systems that don't use the washer/thrust ring. On a later style setup, if the end play is too tight, I guess you could remove material from the timer bushing to set it. But what if it's too loose, even with new parts?

Anyway, thanks for putting up with my ramblings on it.

snapped_bolt · #89 06-17-2016, 12:57 PM

Perhaps that is part of the reason for over 100,000 threads on the Diesel Discussion. Maybe?

"Make adjustments to the washer". I am a machinist. The only adjustments I can make to a washer for any end play would be adding more end play by throwing the washer on the surface grinder and making the washer thinner. This washer behind the timing device has NO provision for adjustment; the only adjustment would be to remove it and install a new one.
If my end play cannot be removed sufficiently, I'll grind down a spacer and install it between the timing device steel bushing and the brass bushing.
Most of the wear is caused by the vacuum pump spring shoving down on that "race track" to keep the roller in contact at all times, I see no provision for the spring to disengage (what? 2 ATM vacuum?!?) (30~lbs?!?) Yeah, that's only a 30 lb spring there,

right?

If your version had the washer, a new steel timing device bushing, new brass bushing and a new washer should bring the assembly up to specifications. Assuming the thrust clearance at the rear of the timing device and the location of the brass bushing hasn't been compromised by wear. For both of our situations a fitted spacer may eventually be the answer.

snapped_bolt

snapped_bolt · #90 06-19-2016, 11:38 PM

I have the feeling the old chain that died was for a gas engine. Just a little diminutive next to the IWIS chain. In fact, I had to press out the rollers on the old chain to get the temporary master link to fit.

After the temp link was attached to the new chain, I started the Pachinko! game. I dropped the tensioner side old chain in first, the whole think went effortlessly and smoothly down to the crank sprocket. I fished it out with a coat hanger, and before I got the whole chain replaced I had to pull the cam sprocket- that's right- ping-ping-clink the notched cam washer dropped to the same spot that the chain dropped. Coat hanger got that, too, but I didn't win any money.

The tool I used to crimp the chain was a knock-off of the Mercedes tool came with partial instructions (1/4 of a page; the steps started at #D) in spite of that, I got the IWIS master link installed and properly crimped.
For the fun of it I ratcheted the crank around and there was no more slapping of the chain against the tensioner rail.
I then finished the cleaning of the rocker sets and installed them (without full torque, just tightened good)- after slathering on some Lubriplate to the shaft, rocker contact faces (upper and lower) and the leading edge of the cam lobes.
I then cranked the ratchet on the crank bolt again. It passes 720 degrees with no signs of hesitation (being caused by slow return of bent valve stems; you also might hear the valve springs snap as the valve stem stops and rises)- we should be good to go, as I thought at first, no valve damage, no head removal, no swissed-pistons.

Now I go back out to REMOVE the cam sprocket, move the cam to the mark, jump the chain, and install the sprocket back on the camshaft.
Next, I need to figure out how to re-install the IP and get ready for drip timing. The timing device is back in as a stand-in until the replacement timing device arrives along with the new bushing and bearing.
I will note that the tensioner rail does not move when the crankshaft is turned. The old one jumped back and forth as I cranked the ratchet, making noise as it did so. My hunch was correct- Mercedes did not design this to wave in the wind, a tensioner is suppose to apply even, slowly increasing tension as components wear.
I am looking forward to driving this car again. It should actually sound and perform close to designed intentions!

Cheers!!!

snapped_bolt