I presume we're talking 300,000 /miles/, yes? I get a bit confused (my own fault) when I see you guys write 300K because being from Canada I just think to myself "oh, 300,000km".

I'm just around 308,000 Km now, so I figure I have a ways left to go before I get /that/ worried about my chain. FWIW, about 192,000 miles.

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

Correct.

Yep... I agree with Brian on this...


As soon as my 617 hits 300k ( in about 13k) I am sending her off to my mechanic for him to replace it... I do not want to mess with the chain and related stuff.. at all. I will help him but he will be in control

TheDon, me too. I've got a ways to go, but when I hit 300,000 (heck, maybe 250,000) I will have the MB dealer replace my chain. I've read up extensively on doing it myself and while it /looks/ within my abilities, I figure it's like this: if I mess up installing a new chain and destroy my engine, it's my fault and I have to deal with it. If MB messes up, I am inconvenienced and they have to deal with it. I'd rather make it someone else's problem than my own.

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

Replacing the chain may cost a couple of hundred dollars .... waiting until the rail goes and locks up the chain and cam and bends valves and potentially knocks dents in the top of the pistons.... well, I am not even going to tell you how much that costs.... you can imagine....
I think it is easier to replace the chain ( and accompanying stuff ) than to do the offset key....

Not really, remove the bolt on the cam sprocket, slide it forward, swap keys and slide it back on. You don't even need to take off the chain.

It took me longer to get the valve cover off than to swap the key.

I've posted pics of this before. Search under my name.

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

Well, then the question comes up of which offset key you chose to use...
How did you measure the stuff that counts in making that decision ?
That is what I was factoring in....
and if you just roll in the new chain and rails.. then you have a new chain and guide gear.... a comforting thought since it is the stuff which touches the chain which is more likely to cause big problems....

Measure the elongation and pick the key that brings it closest to 0.
Fastlane sells the keys you need and makes choosing the right one simple.
http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=2BV1A96NK2C20NAG0D&year=1982&make=MB&model=300-DT-001&category=All&part=Camshaft+Woodruff+Key

I'd offer an opinion, though maybe unpopular.

When I first got into these MB Diesels (16 cars ago), I did every maintenance item by the mile. If I went 3001 miles before the oil change, I felt guilty.

Over the years I've become incredibly impressed with the durability. I choose to bring each car up to snuff and then do maintenance as items fail.

For that reason, I've chosen to not worry about the timing chains. But I also have the ability to go 'out back' and grab another engine (two of them waiting for a home right now).

So, instead of getting overworked on exact maintenance, I've grown amazed at the durability of these cars.

-diesel don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

You sure make that sound easy and quick...

Why don't you list exactly the process (and tools) that he needs to follow to get that measurement correct right here in this thread ?
No reference to other threads in other words... Just tell him how to do it.

For somebody with the necessary skills, tools and will, it is. If I could do it 5 years ago when I was still a noobie then anyone can do it.

Tell? I'll show.
Download the actual offset key guide: http://members.cox.net/lnewcomb99/Documents/CamshaftOffsetKey.zip

This statement by you is the most important concept in this thread.

If a person has doubts about the condition of the chain elongation then they are likely to have doubts about the condition of the more dangerous parts which rub against the chain... what if the prior owner rolled in a new chain 200,000 miles ago but did not replace the rails ?

Then no matter how well you measure and put in the proper offset key your engine is still in danger of calamity ...
and those instructions are not all that clear... lots of discussion in the archives...

All things considered on an old engine in a car you have not owned since it was new... put in a new chain and all the things which contact it ...

The timing chain on my SL was replaced at 110k, apparently they only have a recommended life of 100k on my gasser. I got to see the cracked plastic guides, yikes. This was when the heads were off the block anyway, so kind of a no brainer It seems to be a common cause of engine failure. .

Do diesels have the same plastic guides that can break off into the chain? It was one of the first things I brought up with my indy, but he said that I shouldn't have to worry about it for another 100k or so.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

It is a common cause of chain failure.
If the car is new to you it seems a good idea to check the condition of these guides and rails.... if the engine locks up due to this will your indy pay for the damage ? I would take ' shouldn't have to worry' with a grain of salt...
It may be possible to change out these rails without taking the chain out... I seem to remember at least one side being pulled out the space at the top after being released by the pin....and letting the tension off of the ratcheting tensioner...check the FSM ....