Steve,

I threw that 10deg increment out because I consider that much to be obvious, it might take 350,000 miles to stretch one that much though and if asked I say replace it at 200k. I very seldom measure chains by anything more than mileage and noise. I would replace anything in doubt over 100k. (ALL mileage numbers are my opinion only!!) (The timing numbers for cam ID 11 came from 1985 TDM)


What "noise" do you listen for? My unknown mileage 84 300sd with a smooth idle, and near perfect idle sound jumps into a piston slap/ nailing clack sound just above idle through 2k. Just wondering what a loose chain sounds like.


------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician[/QUOTE]

IMO:
The correct answer is to replace the timing chain if you have any doubts/concerns.

The time/labor to check timing chain elongation is the exact same required to roll in a NEW chain...

Fastlane: Timing Chain, brand IWIS
http://catalog.peachparts.com/item.wws?sku=003 997 62 94

Whunter -
I've got plenty to do & explore. I'm on my 2nd tank w/ Biobor treatment. I have extra filters in trunk for side of hgwy replacements. I guess the timing chain replacement is next since I see no record of it having been done in 236k miles.

leathermag -
"a mechanic" is a trusted BMW/Euro specialist, but by no means a diesel mechanic. If I need to travel 160 miles for a qualified mechanic, the car will be sold. Maybe for a heart specialist to save my life, but not to save the life of a piece of metal. The timing of the pump will be the next option either before or after the chain is replaced. I was expecting 30 mpg+ as my brother had a '93 +- 5 cylinder turbo w/ auto that never got under that (so he says). 4 cyl / 4 speed I thought would be better. To have to go this slow & pay $.30/gal more just doesn't make sense.

Thanks again for all the help & replys. Sometimes it seems these Germans designed things to drive us crazy.

If you read what I said again... you may realize that I was referring the S. Brotherton... if you research his background...
To get it right the first time... from which you could work in the future.... many on this forum would be pleased to have him that close.... a doable drive.... as compared to across the country... like calling Whunter ' a qualified mechanic '.... instead of the specialist wonder wrench he is...

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

To answer the original question, using the marks on the camshaft and crankshaft is quite accurate, if you are very careful. I compared both that method and the "valve drop w/ dial indicator" method and they compared within ~2 deg of crank angle, but search for my post since better than my memory. It is a pain to rig up the dial indicator and I had to get extension bolts from Ace and it was still a bit squirrely. I think 2 deg accuracy is fine since you can't buy "offset keys" any finer to tweak it anyway. I would use an offset key (and did) long before I would undertake changing the timing chain. It is just as good, and you can adjust your injection pump (IP) timing separately to compensate for chain wear. I have never read of a timing chain breaking in these engines.

You can also just live with any timing chain wear. Delaying the valve openings increases max HP (at high rpm) at the expense of less torque at lower rpm. Variable valve-timing controls in current high-end engines do so. Racers often setup a new camshaft w/ 4 deg delayed timing for such improvement. I knew a guy who raced a Pinto and would move the camshaft one tooth back to race it, then reset it for daily driving. Probably more important that you adjust the IP timing. A little advance (~3 deg crank) from the spec gives a little more power. Best to stick with "ain't broke, don't fix it" until you get more experience with your car.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Once again Bill Grissom posts a suggestion which directly contradicts what the Mercedes Factory Shop manual says...which I stated early in the thread.

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html