timing chain BIG UH-OH - Page 2 - PeachParts Mercedes-Benz Forum

blankenship · #16 08-31-2008, 11:50 AM

i'm attaching a picture of what i see at the crank when the camshaft timing mark is lined up...maybe this will clear up some things i may have botched in the description.

from what i'm hearing, it sounds like i could have either:
a) skipped a tooth somehow
or
b) just gotten the cam sprocket and the crank out of relation to each other effected by the slack i had in the chain during the replacement when the tensioner was removed.

am i understanding this right?

i'm totally freaked out. what do i do now?

Stevo · #17 08-31-2008, 11:51 AM

What could be the harm in moving the chain one way on the sprocket then the other if that wasn't the right way? One tooth in the wrong direction then two in the other direction should do it. As long as the engine is turned by hand just to make sure valves are not hitting the only problem that could result is losing timing on the IP, or am I missing something?

Chas H · #18 08-31-2008, 12:19 PM

Quote:

Originally Posted by blankenship

am i really just to try to slip the chain on the cam sprocket? would that risk the chain coming OFF one of the other lower sprockets when the slack gets advanced forward?

should i remove the tensioner AND cam sprocket (with chain) and (while keeping the chain tight and separated from the sprocket) just turn the sprocket one tooth and reassemble?

also, if i'm 20º too advanced at the crank timing mark, which way does the cam need to turn?

Turn the engine to the 0/0 mark. For this small amount you can turn the engine backwards. Then observe the relationship of the timing marks for the cam. Adjust as needed.
You're making waayy to much of this.

barry123400 · #19 08-31-2008, 12:19 PM

Put the crank pulley at top dead centre. Look at your cam with the chain tensioner still in and not much slack. It should be obvious the direction to turn the cam sprocket to line the cam mark up.

It sounds like you are one tooth out. So remove the tensioner and try to work the chain over the cam sprocket the required tooth. Mark a refference with paint on the cam sprocket and chain if you find it confusing or think it might be.

This could happen to anyone and is not a major issue. You have done no damage. The worse problem might be the injection pump is off a tooth as well but you can deal with that later. Probably did not happen though. See how the car runs first after correcting the crank/cam relationship.

blankenship · #20 08-31-2008, 01:17 PM

okay, then. i think B. Carlton's comments just put me on high alert.

anyway, i just put the crank on 0º, and now the camshaft mark is to the left (passenger side) counterclockwise of the TDC indicator.

i guess the problem is that this makes it seem that i would need to pull the chain up a link from the driver's (non-tensioner) side , which has NO slack, even with the tensioner removed. i could easily move it up a link if i were trying to go the other way and pull slack from the tensioner side, but there's no slack on the driver's side to move the chain at all...

now what?

jt20 · #21 08-31-2008, 01:28 PM

removing the vacuum pump will remove much of the risk, if it is worth the time to you. It is putting most of the force on your chain at this time.

Stevo · #22 08-31-2008, 03:13 PM

Quote:

Originally Posted by jt20

removing the vacuum pump will remove much of the risk, if it is worth the time to you. It is putting most of the force on your chain at this time.

Right, between that and compression the chain does "jump" a bit.

Brian Carlton · #23 08-31-2008, 04:29 PM

Quote:

Originally Posted by blankenship

i'm attaching a picture of what i see at the crank when the camshaft timing mark is lined up...maybe this will clear up some things i may have botched in the description.

from what i'm hearing, it sounds like i could have either:
a) skipped a tooth somehow
or
b) just gotten the cam sprocket and the crank out of relation to each other effected by the slack i had in the chain during the replacement when the tensioner was removed.

am i understanding this right?

i'm totally freaked out. what do i do now?

OK, the camshaft is 20 degrees late with respect to the crankshaft. That's almost precisely one tooth (18 degrees).

So, your solution is as follows:

Make sure the tensioner is removed.

Get a bar and rotate the camshaft clockwise. Do not allow the crankshaft to move. The camshaft will take the slack on the tensioner side and use it to allow you to rotate the camshaft and develop some slack on the IP side.

Then, bunch the chain slightly so that it comes off the camshaft on the leading edge of the sprocket (the IP side) and advance this "bunch" one tooth at a time over the top of the camshaft until it finally reaches the trailing edge of the camshaft sprocket and disappears on that side of the sprocket (the tensioner side). You've now effectively advanced the camshaft by one tooth with respect to the crankshaft.

Rotate the engine with the crankshaft at least two full turns and make the same test again with the cam marks and verify that the engine is now 2° late.

If so, then reinstall the tensioner.

Done.

blankenship · #24 08-31-2008, 05:49 PM

Brian- that was great advice and exactly the sort of response i needed. I did what you said, and i'm now on time.

HOWEVER: I've now got a BAFFLING (and scary) problem.. I noticed that my sprocket was eating up the material on my plastic rail, and was not going into the groove above the plastic the rail securing bolt goes through. In order to get the rail into the "sweet spot" it would appear i'd need to add some sort of spacer between it and the head...please see the photos.

Also, my tensioner is only contacting the back half of the chain. It's as if the cam sprocket is just sticking out too far towards the front of the motor! On the passenger/tensioner side, the chain even appears to have come in contact with the front of the head, and "nicked" a little sliver out of the head! (I don't know if it's been this way for a long time, or whether it happened in the past day). How is this possible!!!!

Please look at the photos and help me figure out what the heck's going on here! Don't I have everything assembled correctly? (For the purposes of the photos, I have the rail securing bolt loosened so that the rail could me moved into the 'correct' position...see how much space there is on the backside of the securing bolt?)

Brian Carlton · #25 08-31-2008, 07:30 PM

Quote:

Originally Posted by blankenship

Brian- that was great advice and exactly the sort of response i needed. I did what you said, and i'm now on time.

HOWEVER: I've now got a BAFFLING (and scary) problem.. I noticed that my sprocket was eating up the material on my plastic rail, and was not going into the groove above the plastic the rail securing bolt goes through. In order to get the rail into the "sweet spot" it would appear i'd need to add some sort of spacer between it and the head...please see the photos.

Also, my tensioner is only contacting the back half of the chain. It's as if the cam sprocket is just sticking out too far towards the front of the motor! On the passenger/tensioner side, the chain even appears to have come in contact with the front of the head, and "nicked" a little sliver out of the head! (I don't know if it's been this way for a long time, or whether it happened in the past day). How is this possible!!!!

Please look at the photos and help me figure out what the heck's going on here! Don't I have everything assembled correctly? (For the purposes of the photos, I have the rail securing bolt loosened so that the rail could me moved into the 'correct' position...see how much space there is on the backside of the securing bolt?)

I'm not seeing the problem. The chain seems to be almost parallel with the rear side of the guide........maybe even a tiny bit aft of the edge of the guide.

The tensioner bolt will commonly contact the rear half of the rail contact point. We've seen this before and, apparently, it's not an issue. The SD has the same situation.

It's been some time since I did the SD...........maybe others will have a better idea about it.

Stevo · #26 08-31-2008, 07:52 PM

I know on a 616 the cam sprocket will fit backwards and look 'almost' right, could this be the case, I cant tell by the pics. I looked at another engine to confirm my suspicions when I did it.

blankenship · #27 09-01-2008, 10:37 AM

i'm adding some pictures and notes to clear things up...

i double-checked, and it's not an issue of having the sprocket flipped the wrong way...(the line-up mark i put on the sprocket before removing the head is facing the right way, and the mercedes symbol and writing that are stamped in the sprocket are facing the front of the car, which i seem to remember is correct).

that was a good guess, though, because now i wonder if i assembled everything correctly...the shaft, washers, spacers, etc? the last two pictures in this post show my assembly.

if it weren't for the chain actually riding against the front of the head, i would just add a spacer to to the plastic rail bolt and be very curious, but not so freaked out. does anybody have a 617 engine they can look at and see how much clearance there is down there between the chain and the head?

Brian Carlton · #28 09-01-2008, 10:46 AM

Quote:

Originally Posted by blankenship

i'm adding some pictures and notes to clear things up...

i double-checked, and it's not an issue of having the sprocket flipped the wrong way...(the line-up mark i put on the sprocket before removing the head is facing the right way, and the mercedes symbol and writing that are stamped in the sprocket are facing the front of the car, which i seem to remember is correct).

if it weren't for the chain actually riding against the front of the head, i would just add a spacer to to the plastic rail bolt and be very curious, but not so freaked out. does anybody have a 617 engine they can look at and see how much clearance there is down there between the chain and the head?

Is the cap screw that holds the sprocket to the camshaft torqued to specification..........did the screw seat the sprocket?

Stevo · #29 09-01-2008, 12:20 PM

Quote:

Originally Posted by blankenship

i'm adding some pictures and notes to clear things up...

i double-checked, and it's not an issue of having the sprocket flipped the wrong way...(the line-up mark i put on the sprocket before removing the head is facing the right way, and the mercedes symbol and writing that are stamped in the sprocket are facing the front of the car, which i seem to remember is correct).

that was a good guess, though, because now i wonder if i assembled everything correctly...the shaft, washers, spacers, etc? the last two pictures in this post show my assembly.

if it weren't for the chain actually riding against the front of the head, i would just add a spacer to to the plastic rail bolt and be very curious, but not so freaked out. does anybody have a 617 engine they can look at and see how much clearance there is down there between the chain and the head?

Something is seriously amiss. The best thing would be to have another 617 parked close by to compare, you don't have any MB friends near by? The top of the valves are in the middle of the cam lobs, right, so its gota be up at the forward end.

When folks get back from the holiday surely someone will have seen this problem.

jt20 · #30 09-01-2008, 01:28 PM

I believe you may have put the camshaft on backwards. I think the TDC mark lines up with the keyhole to make this an undetectable mistake. Please check.. not completely positive from your pictures