DANG!! Timing Chain replacement - 603.961
 

'87 300 SDL

Well, I don't know why this isn't the piece of cake that I was told it would be...?!?! ...word of mouth, and the MM implies that the timing chain just feeds right in as you rotate the crank.

All injectors are out. I started at TDC on the crank, and both alignment marks at cam were dead on. ...removed Chain Tensioner. I spit the chain at the at the alignmet marks.

The chain did slip from my claws on the aft side(exit), ...retrieved it and slipped right back on the chain where it had been. Then, the forward RH (CW) slipped in also, ..was retrieved and it fell right back in it's place. I locked both ends of the chain in place and attached the new chain as suggested for it to be fed in, and began rotating the crank cw... :eek:Aghhh!! Then rotation stopped!
I backed it off a bit, attempted it again, and it stopped in the same place. I then backed it off a bit more than the previous time, and had the same results with the crank stopping in the same place! :( ughh... I rotated the cam drive back and forth in small increments to see if it had excessive pre-load. Nope. The crank continues to stop in the same spot.

Now, my million dollar question??? What would the max amount of reverse rotation on the crank be(in degrees), before I screw this thing up?

Also, ...the timing marks aren't even lined up any more! What the hell is up with that?? :mad:

I need some good advise please!

Thanks

Man, I feel your pain. I was just about in the same spot you were with my 617. I don't know your motor as well as the 617, so perhaps just take this as prelim advice. I did alot of turning back and fro on the crank, got the cam gear all off its marks, and lo and behold, I was able to get it back and running just fine.

So, how far did you rotate before it stopped? How far off are the cam timing marks? My guess is that the chain skipped a tooth or two on the cam gear and you've got some valve interference, preventing the crank to move. Don't worry, I think you can overcome that by skipping the chain forward or back on the cam gear. In the end, you probably will have to determine the IP position by removing the hard lines and rotating the engine to see when #1 spits, then set the crank accordingly and reset the cam gear timing marks. No sweat. Good luck.



I tried to think of it this way, there are three variables (Cam, IP and Crank), as long as one remains constant and you can establish that mark as a benchmark you can reset the other two. Luckily my IP remained constant and I was able to reset the other two.

You will need to check the manual as how to do it as you might have to line all timing marks back up just as if you had previously had the engine apart (as if you assembled the engine after a rebuild).
You can line the carnk and the camshaft up easily the problem will be lining up the injection pump timer.
Someone who has replaced a chain that broke on its own should know how to do it.

The cam gear TDC alignment marks are still on the spot. And where the chain links were initially separated, are in the same position on the cam gear. I'm almost certain I don't have valve interference. I don't believe the cam hasn't rotated enough. This interference at the crank feels like it's in the bottom end.

Is it possible for the chain to bunch at the bottom end with the chain tensioner removed?

There again, can anyone tell me how much reverse rotation I can safely put into the crank to perhaps try to work this kink out??

Are there any actual photos out there of the 603 engine with the timing chain cover removed, illustrating the timing chain as routed through the lower end??

When I was going through my mess, I remember asking the same thing--how much reverse action can it take. It was my understanding that the recommendation against reverse crank movement was in consideration of the tensioner failing and causing a skipped tooth. Not an issue with the tensioner out. Again, that was on my 617 which could be different than the SDL. Also, someone here should be able to get you a cutaway illustration from the FSM to show the route of the chain. I think it would be definitely possible for the chain to bunch up at the bottom, but not fatally. When I looked at mine, it was quite evident that the chain will neither skip a tooth or kink permanently in front of or behind the crank or IP.

when changing the head on my 616 engine. i lost ALL timing in my engine, meaning my crank was off, my injectionpump was off and the cam was off. I didnt line up any marks at all. What i did was make sure that no.1 cylinder was at tdc then i rotated the injection pump until it squirted on cyilnder number one. ( Wich should be about 24 btdc correct?) It squirted right on the mark. i put the chain around the injectionpump and that was good to go. Now the cam timing. I put the intake lobe on the first cyilnder to just about to open. Put the chain on . cranked the engine over by hand, no hitting, smooth as silk. Started it up and took off.

I had read on one of the post in this forum regarding timing chain replacement on a 603, that the chain does not feed off the cam gear in a linear motion proportionate to crank rotation. I can not find that post now.

The post stated, I believe that "the vacuum pump gearing acted as a capacitor, in that, significant rotation of the crank didn't always result in the proportionate timing chain being pulled in, but then suddenly 6 inches of chain would be drawn in to the engine".

Is this what I should expect? As I mention in earlier, the initial CW rotation (perhaps 60 degrees) resulted in about 15 to 20 degrees cam rotation. Then every thing stopped...

I'd need to get this thing back on the road today...

All suggestions and/or cowboy tricks from anyone that has experience on this subject with a like type mb engine would be appreciated.

Thanks!

Never been in your sit. w/ a 603.
Do you have enough info (manual) to put it back together if you remove the cams?
Could it be a part of the tensioner is messing w/ the rotation?
On gassersd I hear it isn't the actual chain failure but the tensioner failure that makes the chain break/jump.

Good luck and keep us posted. I would like to know what U discover.


Don

benz,

I have not replaced a timing chain on my 617 (mine busted so i replaced the engine), or even a 603, but from what i have read, and this may sound stupid, are you pulling the old chain out as you are turning the crank? Cause i did not hear that mentioned in your post.

I have been using the WIS M/M on StarTekInfo. I also have access and have been referencing the epc on StarTekInfo/epc.

I am resigned to back all the way up to the my initial starting point if necessary... I can tie the original chain back together where it was initial split. The BIG question, ...as I rotate the crank ccw, and follow up backing the cam gear ccw, is there going to be a problem with the chain bunching.

Also, can someone please confirm my thoughts here. I should expect 720 degrees crank rotation to complete a full cycle of the cam. I believe this is correct?? So would I have to rotate the crank at least, ...what 60 degrees CW or CCW from TDC before I would valve contact if the cam gear is not rotating...?? I can't believe the slop created once the chain tensioner was remove. I'm guessing I saw at least 30 to 40 degrees crank rotation before the slack in the chain caught up and the cam sprocket began to rotate. hmmm...

Also, is the vacuum pump or IP gears preloaded by a spring which would cause non-linear feed of the timing change with the chain tensioner removed.

Thanks for everyone input and suggestions!!

Here's what it looks like behind the cover. Sounds like you got something hung up down there.

http://www.w124performance.com/image...ront_view1.jpg

Did you keep tension on both sides as you rotated it around? How did you connect the old chain to the new one?

The cam rotates twice for every rotation of the crank. It really isn't that big of a deal if the cam skips you can check the timing pretty easy, just don't let the valves hit. It's the IP thats a PITA to reset if you let it skip.

:eek::eek: 603 engines have front covers!? I NEED one of those NOW! :D

[quote=benz_diesel;1779953]
Also, is the vacuum pump or IP gears preloaded by a spring which would cause non-linear feed of the timing change with the chain tensioner removed.
quote]

On my 617, the car did seem to glug glug the chain until, bam!, it'd suck in a few inches. First time it happened, scared the bahjeezus out of me--thought the chain was getting sucked in uncontrollably. But then I got the hang of it, no biggie. Don't know if it was IP or vacuum pump. By looking at that cutaway (which, btw, is a thing of beauty!) I'd bet your chain is a little caught up on that first guide. Also, looking at that pic, there ain't no way your ip skipped a tooth. It's every bit as tight as the 617 in there, and if I didn't skip a tooth doing what I was doing on mine, there just ain't no way you skipped a tooth.

I'm not sure about the 60deg. I would think if the cam's not turning and either of the valves on #1 is open, then you'd probably get contact with as little as 35 or 45 deg on the crank.

That's got to be frustrating for the cam not to keep up at least a little better. Is this common on the 603? Good luck, and keep working at it.

OK, I backed up to assure the cam and the crank were still married to each other at TDC.

Well, ...so much for my confidence in that the chain hadn't slipped a few teeth when it slipped from my hands. And then again (looking at the great photo that Lux sent), I don't see how the chain could skip on the lower end if allowed to get slack. But, apparently it did... I had to back up the chain four teeth to get cam and crank synced. oookay...

So the chain is in, and the cam and crank are married at TDC. Now, ...I'm not so confident if the IP is still in sync.

Has anybody got any old cowboy tricks for setting the IP up? I did notice fuel at the #1 injector when passing through TDC, while checking for clear rotation once completing the chain. I only take that as being somewhere near the ball park. I haven't checked to see when fuel is introduced, so I need to do some reading.

I'm digging back into the m/m now to get a clue about the IP.

I'd like to thank everyone for their help and suggestions. The is a great forum!