timing chain 13Degrees off - PeachParts Mercedes-Benz Forum

RC4U12 · #1 02-11-2009, 11:07 PM

Well tonight i removed the radiator which was easy and checked the timing chain which has 13 degrees after zero till it comes to mark on passenger side{is this right side?} left side is right on at the 0 mark on crank..Now is this normal to be off on only one side? and is this the chain or something else? .Also the chain does not rest on the guide on the left or drivers side on the inside torward center guide,,normall ya no?? Jeff

Roncallo · #2 02-12-2009, 06:16 PM

Quote:

Originally Posted by RC4U12

Well tonight i removed the radiator which was easy and checked the timing chain which has 13 degrees after zero till it comes to mark on passenger side{is this right side?} left side is right on at the 0 mark on crank..Now is this normal to be off on only one side? and is this the chain or something else? .Also the chain does not rest on the guide on the left or drivers side on the inside torward center guide,,normall ya no?? Jeff

That's not right. Something is AFU but I cant tell what from your description. Do you have pictures you can post.

Alkraut · #3 02-12-2009, 08:21 PM

I agree, sounds strange. Did you make sure you turned the crank slowly in the clockwise direction and did not back it up? Also, the crank rotates a lot smoother with the spark plugs removed. Did you leave the tensioner installed when you did the test? Did you notice excessive slack in the chain below the cam gear? You might have a broken guide. What do you think John?

Roncallo · #4 02-12-2009, 09:15 PM

Quote:

Originally Posted by Alkraut

I agree, sounds strange. Did you make sure you turned the crank slowly in the clockwise direction and did not back it up? Also, the crank rotates a lot smoother with the spark plugs removed. Did you leave the tensioner installed when you did the test? Did you notice excessive slack in the chain below the cam gear? You might have a broken guide. What do you think John?

I hope he had the tensioner in place when he did the test. It's ok to have slack in the chain below the right cam gear. The slack gets taken up when you start it and the tensioner gets pressurized. The only way to know if its excessive is if you hear it wrap on startup. Broken guide, if this is happening I dont see how they would not be broken. But the guides don't take up slack except for the tensioner guide and the one below the tensioner.

RC4U12 · #5 02-12-2009, 11:28 PM

Yes i had the plugs out. no i didnt back up the crank..and no i did not take out the tensioner..No slack in chain..
I can take pics tommorow nite. as tonight i removed the alternator, power sterring, smog pump and the rest of the injectors and the injectors from my '73 350 as these are being sent in to get cleaned and tested and using the smaller ones...
dont know how else to explain, the timing marks on the left or dirvers side line up when the vibration damper mark is at 0 and the right or passenger side still not at mark and when i keep turning the crank another 13 degrees the right side comes to mark,,,now the chain does not rest on the inside guide on the drivers side but rests on all the rest of the guides..my guides are all red or brown colored..Jeff

mbboy · #6 02-13-2009, 06:08 AM

Quote:

Originally Posted by RC4U12

The timing marks on the left or dirvers side line up when the vibration damper mark is at 0 and the right or passenger side still not at mark and when i keep turning the crank another 13 degrees the right side comes to mark,,,now the chain does not rest on the inside guide on the drivers side but rests on all the rest of the guides..my guides are all red or brown colored..Jeff

The guides take up almost the entire width of the timing chain compartment, so it's hard to imagine how the chain could not be resting on the inner guide, especially if it's resting on the outer guide. Unless the inner guide slid slightly to one side or the other, as it does, and the chain turned on its side when it fell into the resulting space because it was indeed stretched. But then it would have been very difficult for you to rotate the crank, you would have heard the chain rubbing on the timing chain compartment, and the chain or guide probably would have broken.

In any case, since you already have everything you need to take off to change the guides and chain, evidently because you're going to, I'd replace the old plastic guides with the rubber covered metal guides that Meyle makes, and see if the new chain is still off. My bet is that it will be fine.

Good luck!

RC4U12 · #7 02-13-2009, 09:33 AM

i dont hink you understand..theres two guides on each bank at the top under the gear..one is on the outside of the chain and one is on the inside .. i have pics from this morning i will post..Jeff

RC4U12 · #8 02-13-2009, 12:34 PM

here are some pics ..the timing mark on the vibration damper is out of focus but the yellow line is the zero mark and the pointer to the left is almost to the first hole in the damper{i assume for balencing} Jeff

tyl604 · #9 02-13-2009, 01:38 PM

In picture #4 it looks like something has ripped a slot out of the flange.

RC4U12 · #10 02-13-2009, 03:19 PM

No the notch is there but when i inspected its not from anything unordinary.. but that is the pic that the chain does not rest on the guide....i should have taken one of the other side to show how it does rest on the guide..Jeff

Quote:

Originally Posted by tyl604

In picture #4 it looks like something has ripped a slot out of the flange.

RC4U12 · #11 02-13-2009, 03:33 PM

Now if the chain was off one tooth on the right or drivers side then that 18 degrees would make the timing advanced 5 degrees on that cylinder which would be better than 13 retarded..I did order a 2 degree key incase ..or hopefully to get the rght bank 2 degrees advanced..Jeff

JonL · #12 02-13-2009, 10:10 PM

Here's a theory... I don't recall how the chain makes the 90 degree turn in the "valley." I guess there's a sprocket in there. The bearing or bushing for that sprocket has failed, and the sprocket is now riding high in the block by some amount. That will make the effective length of the chain longer between the right and left cams making the right cam run retarded compared to the left. It will cause the chain to ride high off the rail on the left cam as shown. It will also make the chain run high enough to wear a groove in the cylinder head as shown in the picture. You're going to have to pull the front cover, my friend. Have fun. You're lucky you didn't let it get worse.

RC4U12 · #13 02-13-2009, 10:25 PM

but it ran so nice before i wanted to do this..how can a gear fail and not be run bad? i then have to pu the engine..Jeff

JonL · #14 02-13-2009, 10:37 PM

I don't think the gear (sprocket) failed, but I think the bearing or bushing or pin that locates it has worn out or failed. I may be wrong about my theory (but I don't think I am). You really better check it out because if you simply "correct" the timing by slipping one link and using an offset key, you'll have a much much much bigger job on your hands in no time. This kind of timing error doesn't just "happen" and it shouldn't be dealt with by just looking at the symptoms. You are really lucky you found this. Why did you take it apart if it was running "so nice?" I'm going to try to find a diagram of the chain path....

Gurunutkins · #15 02-14-2009, 12:39 AM

Hi Guys
I think, if i am reading it right, that you just have a very stretched chain. Ive put in a picture of the rotation of the chain, and a picture of the last 116 engine i rebuilt, its just like the 117 but an inch shorter. the scoring on the side wall of the head is very typical of a stretched chain. some better pictures of where the marks all are might help a little more

the chain run is in this thread
Stuck, need help
and the chain direction in this one
Cam Mark Confusion

if you need bigger photos just send me an email
cheers
barri