Was just reading another thread about a guy finding a 91 300D in a barn, and a poster chimed in that the timing belt on some 602, 603, and 606's ran the possibility of excessive timing chain stretch. One symptom was rough running. I'm waiting for my engine mounts to get here so I can replace them, thinking that's why I have the rough idling. BUT, If that doesn't cure it, would the chain be the next place to look? I have 215k on the car. I hope the mounts cure the roughness. Do the chains go "bad"?

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1990 300D 2.5
1991 F350 7.3 Dually IDI

1997 F350 gasser dump
1980 H-D 93 inch Shovel
2000 SE Roadglide

Motor mounts certainly can go bad (and will, after a long enough lifespan)!

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

After a certain amount of miles, does the chain need to be done, like the VW TDI?

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1990 300D 2.5
1991 F350 7.3 Dually IDI

1997 F350 gasser dump
1980 H-D 93 inch Shovel
2000 SE Roadglide

you have to check the chain for stretch... i am not sure how to do it on the om 60X's... on the om 61X's you take the valve cover off and there are marks (inaccurate but an avg is acceptable) or use a dial indicator.

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-Trevor

OBK #12
1980 300SD 333,XXX miles - Totaled
1986 Mazda RX-7 212,XXX miles - impounded and auctioned off
2005 Jeep Liberty CRD Limited 33,000- SEGR, Provent, Fumoto

I can not tell if we are talking about timing chains or belts...
belts are usually changed out according to what the factory suggests... because they can break... my Honda belt is rated at 75,000 miles I think... the 61x engine chains can go way way longer than that... but the trick is that the actual chain does not usually cause the problem... the rails and guides break or come loose or whatever jamming the chain... which is very bad on an interference engine... they cost so little compared to the damage that allowing them to go too long costs that they should be changed at a reasonable interval...

I'm talking about the chain. I just replaced my belt last weekend. Sorry about the questions-- my manual is supposed to be here Monday.

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1990 300D 2.5
1991 F350 7.3 Dually IDI

1997 F350 gasser dump
1980 H-D 93 inch Shovel
2000 SE Roadglide

The chain on our eng. I had replaced at 269000 miles. the replacement chain broke at 70000 miles. there were a lot of things interfering with each other traveling along at 65mph.
There was a couple small plastic pieces and a couple pieces of chain link in the pan. the chain tentioner and rails were replaced, so don`t know really what happened.
Mike at Metric Motors said the sprokets wear with the miles, and a new chain will wear faster because of them.
Maybe I should have left the chain alone and not changed it, this was before I knew about checking chain stretch.
chains don`t need to be chainged with age, just the miles and wear/stretch. belts is miles and age because rubber does deteriorate with age.
Just stay away from the Chineese junk and get good German chain. there are write ups here on the forum about it.
My 2¢

Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

That really is a bummer, change it all out then it still break.
Mike is completely correct... the correct thing to do is replace both the chain, the sprockets and the rails and guides...but that is a much much bigger job when you include all the sprockets..
Sometimes stuff happens despite doing the right thing.... you were right as a matter of principle to change out the chain IMHO.

The engine was just purring along w/o any hint of trouble. drove from Ca. to St. Louis, then on the way back in the middle of Nv. she came apart.

Iam not sure if this was any indication of anything leading up to the chain break. but when we first would start it, I could hear a sort of a ticking or kind of like a raggy belt having a piece maybe hitting something down on the lower right side. best way I can descripe it. when it warmed up the sound would go away. guess I will never know.
That was my $6000.00 chain.

Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

If you check the archives you will find that many people report strange noises when they first start up the car... mine included... so that may or may not have been an indicator something was about to let go...
On the 240 the FSM says to check the oil pressure valve on the back side of the oil pump... they can even fall off... but need to be checked and the proper LB valve installed.. this has changed over the years.. so research it...

Thank you for the heads up on that, I will do a search.

Talking about the oil pump, we had the pan off one time checking on things a few yrs ago. and had to replace the oil pump plastic chain tentioner. It had a crack on two sides where it slides on the shaft. a little more and it would have broken off.

Charlie ☺

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

The incredibly long life of PARTS of our engines often causes us to assume the whole thing is doing just fine... that was great that you found that while you had the pan off...
Another example of the things TOUCHING the chain more often being the problem than the chain itself.... a double roller chain is really strong.

I have seen a om617 waggon with 600k miles on the original timing chain. Yes, most likely it was stretched but the car ran fine, untill it broke. If you do religious oil changes you should NOT have to change that t. chain, well unless it stretches over specs. This comes from an old M.B mechanic. The part that fails before the t.chain on a om617 is the vaccum pump. I don't know much abt latter models...

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DOMAIN NAMES FOR SALE:
www.diesel911.com
www.dieselbenz.com
www.dieseldoctor.biz
Please PM me with offers.

Yep, the sprockets will wear faster with a new chain, and should be replaced. You are right, unless the chain is stretched beyond specs don't worry abt it.

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DOMAIN NAMES FOR SALE:
www.diesel911.com
www.dieselbenz.com
www.dieseldoctor.biz
Please PM me with offers.

Why?

The pitch of the new chain should perfectly match the pitch of the sprockets. The high wear in the sprockets is due to heavy loading on the first few teeth due to a pitch mismatch with a worn chain.