Is timing chain failure catastrophic?
 

If my timing chain breaks on my 85 300d, is there typically major collateral damage done? Or is it replace the chain, adjust the timing issues and drive on?:rolleyes:

catastrophic
 

its catastropic, but my 83 300sd
has a double timing chain so it never breaks... rarely.

After reading probably 1000 posts on timing chains, my general feeling is that the chain on the 617 is so overdesigned that it cannot fail unless there are additional "issues".

Such issues can be items such as a tensioner that fails, or a tensioning rail that wears completely through and the chain fails to maintain tension. This allows the chain to operate outside of its normal path and that's when a potential catastrophe will occur.

So, unless you plan to replace these components with the chain, personally, I don't see the need to replace only the chain. The FSM seems to concur with this and allows the use of offset keys to maintain camshaft timing as the chain elongates due to age.

The SD has 184K on the clock and the chain has 2.5° stretch.

Any thoughts on the timing chain in a 603 engine?

Different deal completely. IIRC you get two?? degrees of stretch and then it must be replaced. I need to confirm the limit.

Only 2 degrees ??? :eek:

:eek: ..... same sort of collateral damage a failed to deploy parachute contributes too.

I'm mistaken. The FSM allows 4 degrees at the crankshaft and then the chain must be replaced. There is no adjustment with offset keys.

i
 

i had a timing chain failure on a 2002 intrepid and
yes its fatal and requires engine replacement..

pistons get out of sinc with valves resulting in bent valves
and messed up pistons....

ihad the
 

vac pump come apart in my 82 300td. broke chain, broke cam, broke cam towers, min repair cost prob about 2000 if hired done.

i went ahead and did the motor while at it. about 4000 now, prob. and up.

tom w

I assume that the chain going out at speed is always going to do major damage. On the otherhand have lost timing belts on interference diesel engines either at startup cranking or when the engine was just turned off. On both occasions there was no colateral damage. Think at very low revolutions perhaps the hydralic lifters compensated enough to prevent the normal damage. Just a guess though but the engines rolled totally over many times before I knew a problem existed and went looking. Assume the newer mercedes engines with hydralic lifters might fare the same way other than the chain is more likely to part company at speed.

Broken chain
 

This happened to me back in the UK on a 1976 300D;

Cam towers
Camshaft bent by .025" (had is pressed streight)
Damage to two cam lobes and followers (dressed surface)
EVERY sprocket destroyed
Injection pump shaft bent
Guides and rails
Timing chain

cost lots of £££ about 800 back in 1985

I did a top end job at the same time because of slight leakage of coolant on the outside of the block. The biggest headache was getting the bottom sprocket off the collar for the oil seal was stuck fast, I had to make a 3 foot cold chisel to split it.

Good thing was the beast started as soon as I got diesel (that nice 50+ cetane european stuff) to the injectors.


Steve

I believe the 603 requires replacement at 4 degrees...
 

A 617 chain and most double row chains for that matter can't be beat, the 603 chain may not be quite as durable, but the jury is still out on that until enough high mileage owners chime in.

My 603 chain has 215K miles and just under 0.5 degree stretch If the same wear pattern is maintained, I should get close to 2 million miles before replacement is indicated. I doubt that the rest, nor I will hold up though.

Change that oil hot and often! (not to steal a quote from notable others) :)

Not really. In a timing chain failure the engine can be rebuilt. In a failed chute deployment, you can't rebuild the parachutist.:eek:

A little more "splat" involved in the parachute incident, wouldn't you think????
:D :D :D :D :D :D :D


Dave

How 'bout the chain on a 602? How durable/rugged?

Currently I'm leaning against preventive replacement...willing to roll the dice.