3-4* timing chain stretch. FAQ's - PeachParts Mercedes-Benz Forum

Ian White · #1 11-15-2009, 12:14 PM

I checked my timing chain stretch with the "cheater

" method last night. I was too lazy to break out the dial indicator... I lined up the cam and cam tower timing marks, and the crank is off about 3-4*. What would ya'll do? It seems to me that this is within spec (coming from memory

), but I couldn't find a thread where it said. Thanks for your input...

Stevo · #2 11-15-2009, 02:28 PM

I would start thinking about replacing the chain if it were at 5 degrees, I wouldn't worry about it now, but thats only what i would do, a half dozen other folks will probably have have six other ideas.

sasquatchgeoff · #3 11-15-2009, 02:34 PM

Check it w/a dial gauge to make sure, but I would drive a vehicle another 200K with chain elongation between 3* and 4* - is this on the SD?

Ian White · #4 11-15-2009, 02:38 PM

Quote:

Originally Posted by sasquatchgeoff

Check it w/a dial gauge to make sure, but I would drive a vehicle another 200K with chain elongation between 3* and 4* - is this on the SD?

Yeah it is for the SD, the engine is out of a 1984 300D with 256K. I am in the middle of replacing the engine (again).

79Mercy · #5 11-15-2009, 03:41 PM

4 degrees is fine, donotworry one bit about it.

Billybob · #6 11-15-2009, 03:54 PM

You're replacing an engine for the second time with an engine of substantial mileage unknown pedigree and actual condition, and your cursory examination shows at least 4 degrees cumulative wear elongation.

Not to sound like Mommy buy, penny wise, pound foolish?

The best new chain IWIS cost about $100, sounds like cheap insurance that I’d gladly pay unless this Engine R&R stuff is a fetish for you!

If you just don’t have or want to spend the coin I understand completely, I’m just making a risk vs. rewards devils advocate arguement.

C Sean Watts · #7 11-15-2009, 04:48 PM

Margin of error for the "cheater" method can have you well beyond the limit. Rolling in a new chain isn't all too hard, especially when you can rent a chain crimper from other forum members.

leathermang · #8 11-15-2009, 05:21 PM

Ian,
You did not check the chain elongation..
so the rest of this thread is Moot..
except for the people who said it is better to just roll in a new chain...
That is the safe thing to do if you are too lazy to actually check the elongation..... and possibly use the offset keys available for the intermediary stretch situations.

Ian White · #9 11-15-2009, 11:06 PM

Quote:

Originally Posted by leathermang

Ian,
You did not check the chain elongation..
so the rest of this thread is Moot..
except for the people who said it is better to just roll in a new chain...
That is the safe thing to do if you are too lazy to actually check the elongation..... and possibly use the offset keys available for the intermediary stretch situations.

Alright, what is the difference between chain elongation and stretch? Nothing IMO, What is the proper way according to you then? Check with dial indicator...?

pawoSD · #10 11-15-2009, 11:11 PM

I think MB FSM calls for replacement (or keys) at 7 degrees. When I bought my SD and had the dealer do an inspection and valve adjustment on it way back....it showed 11 degrees of stretch.

Needless to say I had a new chain put in, it ran A LOT better after that. Since then I've done over 72k.....and it has not even stretched 1 degree yet. Probably due to my anal 4-5k synthetic oil change interval.

Side note: 11,000 posts!!!

compress ignite · #11 11-16-2009, 12:08 AM

When you replace the Chain,should not also the SPROCKETS be given some
consideration?

I know,that Crankshaft sprocket requires R+R of the Timing Cover...

pawoSD · #12 11-16-2009, 12:34 AM

Usually the sprockets have little to no wear on them if the engine received proper oil changes......mine all still have production marks on them, brand new looking with 284k!

charmalu · #13 11-16-2009, 11:37 AM

Quote:

Originally Posted by pawoSD

Usually the sprockets have little to no wear on them if the engine received proper oil changes......mine all still have production marks on them, brand new looking with 284k!

IF. it had regular oil changes. things are iffy when buying a used car, never know really what the prior maintenance was.

When I bought the 85 back in 97, it had 176,000 miles on it. no documentation of any kind, so it is from that point I babied it and did the regular oil changes at every 3000 miles and so on.

had the timing chain replaced at 269,000 miles as a preventative measure, didn`t really know what the streatch was at the time. I had the shop do the valve adjustment etc..... thinking this chain would take me onward towards the 500,000 miles I read about on e-bay

.

Then as in my sig, the timing chain broke with only 70,000 miles on it and the engine with 331,000. Picture what the Moon looks like, and eastern nevada looks similar. we are out in the middle of no-where, sort of.

When we picked up the new engine from Metric Motors, Mike told me, even though the chain was replaced, the sprockets have wear on them, and wear into the new chain.

Charlie

leathermang · #14 11-16-2009, 10:52 PM

Quote:

Originally Posted by Ian White

Alright, what is the difference between chain elongation and stretch? Nothing IMO, What is the proper way according to you then? Check with dial indicator...?

The FSM specifically forbids using the towers to do anything except getting the general parts in the right quadrant DURING BUILD UP OF THE ENGINE.
Lots of discussion in the archives. Using the towers for trying to determine the chain elongation is not permitted according to the engineers who made your automobile. So using that method is akin to the old saying ' garbage in, garbage out' ... you have no useful information after that procedure.

Stevo · #15 11-17-2009, 10:00 AM

Quote:

Originally Posted by leathermang

The FSM specifically forbids using the towers to do anything except getting the general parts in the right quadrant DURING BUILD UP OF THE ENGINE.
Lots of discussion in the archives. Using the towers for trying to determine the chain elongation is not permitted according to the engineers who made your automobile. So using that method is akin to the old saying ' garbage in, garbage out' ... you have no useful information after that procedure.

Yah, but its a quick and easy way to get a "pretty good' indication of whats up with your chain.