Timing Chain Stretch, IP timing ???? - PeachParts Mercedes-Benz Forum

winmutt · #1 05-28-2007, 04:28 PM

I measured timing chain stretch today, measured at 12 deg. Should I get go ahead and get the offset key? Which one? 4deg? I remember some discussion about which one was the correct based on 2x rotation of cam to crank.

Also, this is the winner I think for my poor starts. IP timing was around 18-15' BTDC. Despite what everyone said I could not get the pump to produce fluid by turning the crank but found I could by turning the steering pump. It may have been even closer to TDC as I was in a rush by the time I managed to get the pump belt tight enough. I did find the original aligning marks of the IP and it was still in factory position! So it looks like next weekend I will be fixing timing atleast and perhaps the cam key as well.

jbaj007 · #2 05-28-2007, 04:49 PM

At 12º stretch, roll in a new chain.

winmutt · #3 05-28-2007, 11:11 PM

Quote:

Originally Posted by jbaj007

At 12º stretch, roll in a new chain.

This was at 2mm lift so its 1' out of spec, 3' for a new chain. That should be ok right?

#4 05-28-2007, 11:38 PM

A 2* (4 at the crank) key would work well and don't forget to get your IP timing back to 24* at the same time.

jbaj007 · #5 05-29-2007, 12:02 AM

I thought you meant the "screening" technique (not as accurate, but quick

) where you line up the mark on the camshaft sprocket/washer with the mark on the bearing tower; then read the degree stretch at the pointer at the crank balancer. 12º would be a lot with that technique. Sorry I ASSumed

winmutt · #6 05-29-2007, 02:52 PM

Quote:

Originally Posted by ForcedInduction

A 2* (4 at the crank) key would work well and don't forget to get your IP timing back to 24* at the same time.

Here is the age old question, whats the correct part number? I have read many conflicting stories about which key for how many degrees.

Also can someone estimate in->deg for the IP? The IP is at stock timing accoring to the alignment marks. Would 1mm get me 2' ?

Bajaman · #7 05-29-2007, 03:14 PM

Isn't 11* the stretch measured for a chain with 20k miles? If you measured 12*, then you've only got 1* beyond that. The smallest woodruff key that I can find is 4* which would put you back at 8* at 2mm lift. This would be 1* earlier than the 9* spec for a new chain. I have also been thinking about this as i measure between 12 and 12.5* stretch on my chain. But since it is so close to the 20K spec, I opted to leave it.
bb

dannym · #8 05-29-2007, 03:21 PM

I don't think you measured properly. You didn't mention what vehicle your testing so I'm going to assume it's the 1985 300D.

First you get your reading at the ballancer then you go to the FSM where you'll find this:

Quote:

For engines 617.950 (1980 and after), 617.951, 617.952; Camshaft code 05, specs are:
With new chain, 9 degrees ATDC.
With used chain (from approx. 20,000 Km), 11 degrees ATDC.

It looks to me like your only 1 degree out of spec.

http://www.peachparts.com/Wikka/OM617TimingChainStretch

Danny

dannym · #9 05-29-2007, 03:22 PM

Oops bajaman beat me to it!

I would not do anything to a chain with 1 degree stretch.

Danny

winmutt · #10 05-29-2007, 03:47 PM

Sweet, why in gods name is the IP so far out then? Its aligned at factory marks by the looks of it, I bet a new one was rolled in and they just set it back to factory, 20k later it went all to crap and the new owner never bothered to get it fixed?

If thee chain is 1' off spec and 3' off NEW spec then why is IP timing like 6+ off?
IP timing 2x Crank as well?