I just did the maintenance on my 83 300D. While I had the valve cover off I checked the timing chain for stretch using the method discuss by MB DOC and others on this forum. It is at the 3 degrees that MBDOC suggested replacement. My rails appear to be in good shape. Is rolling a new chain on in place of the old one as easy as it sounds, and are there any steps that need to be done as prep work. I plan to do this soon as a precaution.

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Keith Schuster
2006 E350 98K miles
2013 Ford Explorer 15K miles

Keith, your timing chain does not need to be replaced if your timing is off only three degrees. The MB factory manual states"If a timing correction is required it will be necessary to use an offset Woodruff key,or to fit a new timing chain if the old one is stretched too much.
Offset keys are avaible for 4 to 10 degrees correction. The part No. for a 4 degree correction is 621 991 04 67.
Good luck
Bill Lewallen Lexington,Ky.

I will go along with that. But that leads to another question, will a 2 to 4 degree stretch effect performance enough to warrant fooling with a key replacement. or should I not be to concerned with it. My biggest fear is that I would have a chain failure, then a major engine repair on my hands. Although I have no other vehicle to compare with, the car seems to run well. Thanks for any replies.

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Keith Schuster
2006 E350 98K miles
2013 Ford Explorer 15K miles

Wm. Lewallen,
Hello, I am new here and noticed you live right down the road from me! I am in Frankfort, Ky. and work in Louisville.
I just purchased an 83 MB 300SD a week ago with 196K miles on it. I am the second owner! The car was well maintained with all the records from the dealer in Louisville.
My question is this, what is the minimum average milage that this car will go before I should be thinking about a new timing chain? I have had other diesels so I am just getting used to any noises that this car makes. Will the time chain make any racket if it gets a little slop in it? The car seems to run fine, but I am just trying to get all the info I can.
Thanks for any Help!

P.S. The trans is original, if the fluid is changed on a regular interval, how long will they hold up?

With only three degrees off in the timing,you don't need to replace your chain. You could be off one degree just by the way you held your head when looking at the TDC mark on the vibration damper. A more accurate method is with a micrometer. A chain that is really stretched(worn) will make a noise when the engine is started after setting for a while. The oil will have drained out of the tensioner. and the chain will flop around until the tensioner is filled with oil. If you can see chain marks on the inside of the valve cover, then it is really time to replace the chain.
Bill Lewallen Lexington,Ky.

Kieth, IMHO, I would change the chain if you have any doubts about it. I didn't change mine and it broke, took out the cam(broke into 5 pieces),three of the cam bearing towers, and some valves as well as all the guides and tentioners. The chain only costed about $70-80. I had about 5 or 6 degrees strech. Just my HO. Good luck Jay

Thank's for the input guy's. I agree with Wm. Lewellen on what angle I looked at the balancer. With that in mind and thinking back it was closer to TDC than the 5 degree mark. So I am going to wait and recheck at my next oil change and valve adjustment. Now that I know what I'm looking for I can monitor it closely.

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Keith Schuster
2006 E350 98K miles
2013 Ford Explorer 15K miles

My thoughts on timing chain service:

Offset key -- correction of timing due to worn chain.

Relacement -- Correction of worn part.

From my own exp., replacement is easy to do and short $$$, so that is always my route.

Arthur

I have a 1980 300D non-turbo. I replaced the original chain at 216k miles and found the car was still a dog, albeit a friendly dog. 8^). I had measured timing chain stretch at between 5 and 6 degrees, it's hard to get exact without having measured several by mic and then comparing that to the crankshaft position.

The replacement is medium DIY difficulty, IMHO. Be aware that when they say to cover the opening under the cam sprocket when you cut out the rivets, they are very serious. It is also important to understand that if anything drops down that hole when you're replacing the chain, your day just turned brown. You also don't want to try this by yourself; you need help feeding the new chain, puloing the old chain, turning the crankshaft bolt, and keeping tension on the chain as it goes around the sprocket. BTW, I saw no wear on any of my guides and I'm told the biggest factor in guide wear is how religious your oil change history has been. My car was well maintained before I got it and I've changed at 3333 mile intervals with Rotella since 160 k miles.

Plan on giving yourself 2 hours for just the timing chain. You also want to check the valves when you're done since you're putting a new valve cover gasket on and don't want to go through this again sooner than you need to, right?

Mike Yox