Well, it seems like if I go with a new chain, I am looking at a chain, tensioner, rails, press (maybe I can borrow one), and possibly new oil chain and oil chain tensioner (have no idea about THAT job!)

Seems like I am up in the $500-$1k range DIY, so I shudder at how much an indy would charge.

I will measure with the other method this weekend and think about my options and report back

Thanks for all your comments so far!

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

No oil pump chain to worry about but it wouldn't hurt to pull the pump and check the bushings inside for ware.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Besides the stretch of 8 degrees. You probably have no proof the chain is not the original one. I noticed your overall indicated milage reading.

Even if it is accurate the chain might have been in service almost too long already. May be dangerous to exceed 300k on the original chain. Thinking fatigue. The gentleman that pointed out sprocket wear is correct as well. The other problem i feel occurs. As wear progresses it actually increases at a faster rate. This may be subject to some consideration . Some people do not believe that but I personally do.

Total agreement with worn parts continue to wear at a greater rate. I read the same in a Motorcycle Engineering book (that is lost in my house somewhere).
In the book they had a section on chain/sprocket wear.
As the sprocket wears the chain rides up higher on the gear teeth. In a sense the chain is trying to ride up over there top of the tooth of the gear but a machined part of the gear holds it in position. When that portion of the gear wears the chain moves up on the tooth stressing the chain and wearing the tooth in at a point it is not supposed to wear at.

It is sort of like the distance between the Chain Links and the Gear Teeth are timed to each other.
A new Gear with a stretched Chain is not timed well; a new Chain with an old Gear is not timed well either.
That is my opinion

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84 300D, 82 Volvo 244Gl Diesel

If someone wanted to determine if they had the original chain they could inspect it to see if it has a master link. When the engine is assembled at the factory the front is open.. so they put on a chain with no master link.... seldom would it get rebuilt later in that style.... so ' no master link' pretty much means original chain.

I think it dangerous to use motorcycle chains and sprockets as the way we conceptualize our chain and the wear characteristics. While some motorcycles had enclosed chains and good oiling systems... most did not...and the quality of the sprockets may not be in keeping with what MB puts on their high dollar engines. This is also a double roller chain.. side pressures and load spread would be very different...
If you compare 10,000 mile increments on the engine... the most relative wear will occur in the first 10,000 miles.... compared to for instance the time from 190,000 to 200,000. I do not remember what increment they use.. but this concept is straight from the Factory Shop Manual ( Surprise,Surprise .. for those of you that know me )....
New chains and ' touch feely' peripherals are so cheap compared to the damage done by a lockup ( typically bending valves and potentially breaking pistons ) that I would think it prudent to change out the stuff somewhere in the 200,000 to 250,000 mile range.

can you elaborate on 'open'? How is the front originally installed?

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