Who has the most miles on their original timing chain?
 

I am really wondering who is the mileage champ on the original timing chain?

So far I got 241k miles on it.

I'm currently changing mine. 1984 300CD 290,000 miles. I'm the second owner for the past 4 1/2 years. Don't see any record of it being changed in the past. When I tore into the engine, the tensioner rail was worn into. The tensioner piston was galled on the end & all the other guides looked old & brittle. The chain itself though was hardly stretched-about 1/16 inch on the whole length-they're pretty tough. Paul central FL

i dont know if my chain has been changed or anything ill check it when i do a valve adjustment but ive got 260k on my engine and lord knows how long its been since a valve job was performed

I have 320K on my 96 E300

I changed the timing chain on my old 78 300d a couple of years ago. Had 345 on the clock at that time.
Biggest thing I noticed was that it immediately quit with the idle miss that was a plague with that car. The banana slide was almost worn through.
Ran a lot stronger after that, had 12 degrees stretch on the old chain, that was measured without a dial guage.

84 300CD with 360k and still truckin..
 

had 150k on it when I got it and it had never been touched

This is like a 'how many times have you played russian roulette?' competition. Ooo Ooo, I spun the barrel 5 whole times!

Remember that if that chain goes, it can do severe damage to your engine... I'd rather take the time to change it, then push it to the limit and risk engine destruction. Its not an incredibly difficult job, and its better than the alternative.

peace,
sam

PS Mine was changed at 240k, and it needed it.

Mine had 340 when changed.

254k and I am going to change it this winter. The chain has 3.5-4 degrees of stretch in it so its right at the limit.

I agree, mine was replaced at 212k about half a year after I got the car (had 207,128 when I got it), it had about 3 degs of stretch I think....nice new one been hummin' away in there the past 20k....its a very comforting thing. :D

244K on my '85 300D and had no stretch the last time I did a valve adjustment.

Why would Mercedes make a 10deg woodruff key if the limit is 4deg?

danny

Quick chain concept filler:

Chains do not 'stretch'. We use the term 'stretch' because they get longer, but its not because the links are actually physically elongating.

A chain is formed of links, flat pieces of metal with holes in them, and pins, which slide through these holes. There is usually a bushing of some sort in between, but not always (the link is often doing double duty as a bushing). The pin is constantly rotating within the hole on the link, and with time, it begins to wear the hole out, and the hole gets larger. But it doesn't just get overall larger, it becomes oval shaped, since the pin is always putting pressure on one part of the link (the driving edge). As this happens, the pins get farther apart, and the chain gets longer.

Now, assuming that this stretch, or elongation, doesn't cause the chain to straight up break (which it can do), then it causes two problems:

It changes your timing, because more chain is now taken up by the tensioner. This is OK, because you can adjust the timing to compensate.

The worst problem, really, is that the increased pitch of the chain (the distance between the centers of the pins) is increasing, which wears out the sprockets.

Imagine a brand new chain and sprocket. As the sprocket turns, each pin falls right in between two teeth. But as the chain ages and elongates, the pins fall farther and farther forward, and begin to eat away at the tooth in front of it. This creates a 'shark tooth' appearance on the teeth. The result is that the sprocket's pitch will increase (the effective distance between teeth) as well.

So far, this is OK. You've got a longer-pitch chain, and a longer pitch sprocket, but they are matched, and you can adjust out the timing difference.

But here is the problem! When you replace the chain, you now have a chain with a shorter pitch than the sprocket, and they are mismatched! Now the chain will wear out very quickly, because the sprocket will force additional wear on it. Additionally, the fresh chain will scrape away the other edge of the teeth, making them smaller and smaller. Soon, one of a few things will happen, you'll break a tooth, or you'll break a chain.

Here is a lesson from the cycling world (and motorcycling world too).

In cycling, we use a 1/2" pitch chain and sprockets. You always replace a chain when the length of 12" worth of links has increased by 1/16" of an inch. The chain isn't in danger of breaking at that level of elongation, but it means that you haven't started destroying your sprockets yet. If you wait until the chain elongates to 1/8" or more over 12", then you'll need to replace your sprockets AND your chain at the same time, which is more difficult, and more expensive. 1/16" of wear over 12 inches corresponds to about .5% elongation. 4 degrees of elongation in a timing chain corresponds to about 1.1% elongation. And finally, let me tell you, I'd rather replace 100 bicycle cassette sprockets, than have to replace one main crank sprocket on a 617.

So anyway, I know that is really long, but its important information to know, when talking about chain/sprocket systems. You replace the chain sooner than you might think, in order to prevent damaging the sprockets. Timing chains are cheap compared to the sprockets they ride on.

peace,
sam

85' 380se (264k)
 

Sorry, mine is not a diesel, but it is a Mercedes. I have 264,000 miles on my 1985 380SE. I have no clue if the chain is original, because there were NO records. The guy I bought it from bought it in 2000 after the original owner traded it in @ a new Mercedes dealer. The car ended up at an auction in 2000, which is where the guy I bought it from bought it. He bought it when it had 221K miles. I am sure that the original owner must have changed it and the tensioner at least once, because it is still quiet. I have heard that they will chatter badly when cold if the chain and/or tensioner are bad. Luckily, mine is not chattering yet, so I hope it has been changed, because if it breaks, you know what happens.

Its the rails and guides that do concern me, because I have heard even though they are not on the "service interval" to change, they can still get old and brittle, then break and get caught in the chain, then in turn, bend the valves. Pretty poor design on this if you ask me.

I am wondering, do the diesels also have these "upper rails" and "guides" that are subject to breakage?

No body near 400k yet?