Help! om603 jumped timing when replacing vac pump gear! - PeachParts Mercedes-Benz Forum

BenzTurbo · #1 10-11-2014, 08:37 PM

while replacing the timing gear for the IP, i managed to jump the chain a few teeth on the crank!

everything was going well and then i went to torque down the reverse threaded bolt for the IP gear and i heard the awful noise of the chain hopping off the crank. i forgot to re install the tensioner!

i have no idea how many teeth it jumped either. with 15 degrees ATDC showing on the pointer, the IP locking tool would not seat. how often are the crank indicators off? i feel awful now and am hoping i didn't completely screw this up. i don't know what to do next? is it as easy as lining marks on the cam and crank up, getting the locking tool in the IP and getting the chain on the sprockets or am i screwed because the crank position pointer may be off?

vstech · #2 10-12-2014, 12:15 AM

I'm HOPING I'm wrong, and there is an easier way, but afaik the cam needs to come out, then the crank set at 0, then the cam lined up with the timing mark, then the ip timing gear set in place, then the tensioner, then rotate the crank to 15, then install the ip with the locking tool in place...

ah-kay · #3 10-12-2014, 12:29 AM

My experience is that the chain cannot jump a teeth at the crank shaft no matter what you do. The front cover physically restrict the chain and it cannot jump to the next groove. Did you remove the IP, i.e. the chain is off the IP gear?

BenzTurbo · #4 10-12-2014, 12:45 AM

That is exactly what i needed to know! Thank you! so with the crank at "0"and the cam marks lined up, the valve timing will be restored? i will probably remove the cam to prevent damaging a valve. IP timing seems straight forward and i have the locking tool.

vstech · #5 10-12-2014, 02:21 AM

Quote:

Originally Posted by ah-kay

My experience is that the chain cannot jump a teeth at the crank shaft no matter what you do. The front cover physically restrict the chain and it cannot jump to the next groove. Did you remove the IP, i.e. the chain is off the IP gear?

This is good news, if the crank can't skip a tooth, and the cam is still in time, maybe only the IP gear spun, and all that's needed is to tension the chain, and reposition the IP. BUT I THINK THE IP GEAR CANNOT SKIP. The cam may have skipped...

A simple test would be to install the tensioner, and VERY GENTLY rotate the crank to feel for resistance. If the motor will turn 90 degrees, keep turning the crank by hand until the cam mark lines up and see where the balancer is reading.

BenzTurbo · #6 10-12-2014, 03:08 AM

the cam sprocket was and still is zip tied. the cam mark is almost lined up and the crank indicator is pointing past the 40 degree mark. i forgot which way but i would have to turn the crank clockwise a bit to get it to 0 degrees. i don't think the the chain jumped off the IP timing device sprocket but i may be wrong. i just kinda freaked out and called it a day after that happened. with the crank being so far off, the cam/ crank relationship has to be off. i don' think the indicator can possibly be that wrong.

vstech · #7 10-12-2014, 10:58 AM

40 eh...

See if you can rotate the crank back to 0... It sounds like the crank rotated in reverse taking up the slack from the missing tensioner...

ah-kay · #8 10-12-2014, 11:29 AM

I do not know what you have done but I can tell you.

1) Cam timing has not changed because it was zip-tied.
2) Crank timing has not changed because the front coverr would not allow it to.
3) Not sure whether you had removed the IP sprocket and move the timing chain???

I would relax and re-trace your steps in the IP area. I am sure you can get it back it what it was. The tensioner would take up the slacks of the chain. I was in similar position before.

BenzTurbo · #9 10-12-2014, 12:16 PM

Are we sure the chain cannot jump on the crank? There was indeed a lot of slack with no tensioner so vstech is spot on what I think happened. I thought the oil pump chain was in front of the timing chain so how are there guide pins to prevent it from hopping off like the one on the IP timing sprocket? I've never had the front cover off so i don't know. I'm about to start working on it.

Mxfrank · #10 10-12-2014, 03:49 PM

Quote:

Originally Posted by vstech

I'm HOPING I'm wrong, and there is an easier way, but afaik the cam needs to come out, then the crank set at 0, then the cam lined up with the timing mark, then the ip timing gear set in place, then the tensioner, then rotate the crank to 15, then install the ip with the locking tool in place...

This is the right thing to do, even if you can convince yourself that there are corners to cut.

BenzTurbo · #11 10-12-2014, 03:53 PM

Update: i started work on the 603 today and i do not believe it the chain jumped time on the crank so valve timing has not changed. the chain was jumping on the IP timing sprocket when i tried to tighten or loosen the center bolt because i did not re install that pin yet. so the IP timing is way off which is a huge relief! i put the tensioner back in and turned the engine over by hand at least 5 times and there was no weird resistance i could feel. but when 15 ATDC came around, the cam marks were still off. i think the indicator is wrong because before i even removed anything, i noticed that the locking tool wouldn't work anywhere near 15 degrees. this is a problem because i need that for IP timing. what do you think?

BenzTurbo · #12 10-12-2014, 04:44 PM

i dont know what i was thinking. the cam mark should line up with the crank at 0, not 15. but it is still way off. with the cam mark lined up, the crank is at about 45 degrees. could the pointer be bolted on upside down or something like that? i can't imagine the valve timing could be that far off and the engine could still turn?

GregMN · #13 10-12-2014, 05:02 PM

15 AFTER TDC. The photo shows 15 Before TDC.

The IP timing ridge will be in the center of the viewing port on the IP every other revolution of the crank. Not every one.

Set the crank to 15 ATDC
remove the IP
swap out the IP timing gear / vacuum lobe gear (what ever you want to call it )
install the cam gear
Lock the IP timing ridge in place
Install the IP
Install the tensioner
Rotate the crank twice by hand
check the IP viewing port to confirm the timing

BenzTurbo · #14 10-12-2014, 05:14 PM

Quote:

Originally Posted by GregMN

15 AFTER TDC. The photo shows 15 Before TDC.

The IP timing ridge will be in the center of the viewing port on the IP every other revolution of the crank. Not every one.

Set the crank to 15 ATDC
remove the IP
swap out the IP timing gear / vacuum lobe gear (what ever you want to call it )
install the cam gear
Lock the IP timing ridge in place
Install the IP
Install the tensioner
Rotate the crank twice by hand
check the IP viewing port to confirm the timing

the IP is currently out now and the timing basket is holding the sprocket for it in place. i know i screwed up on the BTDC and ATDC. sorry bout that. but i'm still confused about the cam and crank timing. why wouldn't the marks line up? i don't want to destroy this engine on startup or something. am i checking it right?

BenzTurbo · #15 10-12-2014, 05:48 PM

could the crank pulley have been installed wrong?

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