Timing Chain question
 

So, up front, I'm not trying to troll, or be directed to another thread dealing with this issue.

My question is this. How many people still have the original timing chain in their car, and if so, what is the curent mileage on it. Looking for data to compile a maintenance spreadsheet/failure analysis on engine components.

Many thanks,

I'm @ 165K on the original. I know not that much... I've heard they can go about 300K.

Dkr.

Elongation is the indicator of chain wear/life, not odometer reading. Make sure you check for an offset key if you don't know the car's service history from new.

Sixto
98 E320s sedan and wagon

205K

still on original chain.

I did the 2mm lift method for measuring stretch and it showed 2degrees. which is pretty much no elongation.

that was my first time checking it with a dial indicator, so I may have done it wrong.

but they seem like stout chains, and should last quite a while with proper oil changes and maintenance.

I've read that the guides and tensioner probably wear out quicker.

225 miles on what I think is the original chain. All of this applies to a 617.952

However, if you look in the threads about timing chain stetch or the 2mm method what you find is that people with similar milage have quite different timing chain stretch.

I believe one of the things that determins timing chain wear is if the Oil is changed when it should be and the type of Oil used.

If I have picked the correct threads to post what I found out about Timing Chain Failure is that it is usually caused by Vacuum Pump Failure and it is the pieces of the Vaccum Pump getting into the timing chain mechanism that causes it to snap.

Vacuum Pump breakage appears to be called by either the bearing cage falling apart and or timer bushing wear to the extent that there is excessive end play.

MY Question on Timing Chain Failure
Who has or knows someone that has experienced a timing chain breakage/failure? - PeachParts Mercedes ShopForum

My question What in particular causes vacuum pump failure?
http://www.peachparts.com/shopforum/diesel-discussion/204187-what-particular-causes-vacuum-pump-failure.html

Vacuum Pump Failure with pic of worn Intermediate (timer) shaft bushing
http://www.peachparts.com/shopforum/diesel-discussion/355899-vacuum-pump-failure-picking-up-pieces.html

I have not seen anyone post evidence that the Timing Chain just fails because of too much stretch. Althoug I guess that is possible.
Also you have timing chain tensioner issues that can effect the timing chain.

Consense seems to be that you check it with the 2mm Method as in Post #4 and make a decision based on that to replace the Timing Chain or use an offset Woodruff Key to corrrect what is actually the camshaft timing to correct the camshaft timing due to the stretch.

Then there is the Timer end play.

I thought I would add that this changing the timing chain at X amount of miles seems to be related to gasoline Engines and in particular those Engines where the larger of the 2 taming chain gears came from the factory with plastic teeth. And those were roller chains. Usually single row roller chain.

Other Gasoline engines that have timing chains that don't have roller chains have those timing chains with small pins and the teeth on the chains are made with multiple sheet metal teeth.

Since the design is different the milage for them I don't think can be compared to roller chain or the double row roller chain on the mercedes.

I think what this means if you go to a shop and ask when a timing chain should be changed they are going to fall back on their experience with non-mercedes gasoline engines for the answer.

Is there a point that MPG falls because of chain elongation? There might be an economical threshold to replace the chain.

Sixto
98 E320s sedan and wagon

wouldn't you just add a woodruff key at that point?


not sure what criteria MB uses to replace the chain or add a key to correct timing.


I am no expert and this is just regurgitation from stuff I've read here.

Doh! And time the IP. I'm stuck in the 603 world :p

Sixto
98 E320s sedan and wagon

On w123s and w124 diesels I've typically changed them at around 250k miles. I also change out all the guides, slid rails and tensioner of the timing chain and oil pump chain tensioner. The one you will find the most wear on is the tensioner on the oil pump chain, in addition on the w123 you will see a wear mark on the oil pump tensioner spring. Something about the way it is positioned in there. The most mileage I've changed an original chain/tensioner on was 320k+ miles on a 98 E300 and it was still running good when I changed them as preventive measures.

I have yet to do a MB v6/V8 timing chain/tensioner. I seem to vaguely remember doing an 83's era SL but can't say for certain.

Close to 300k on my OM616 240D. I think it's the original chain. Still very tight but it's always in the back of my mind.

The timing chan elongation effects camshaft timing so eventually it would effect MPG; especially if you did not re-time the Fuel Injection Pump as the Timing Chain elongates.

Not the timing chain but there is a little snap righ that wears on the Oil Pump Chain Tensioner. When that goes it is pissoble for the tensioner to jam up the oil pump drive.

You can get at it by way of small oil pan removal.

The green arrow points to the snap ring.

Not uncommom for the om606 chains to last 320k plus. My 98 didnt get changed until 350k (i bought it with a rattling chain) and 390k on my 99 e300 with 450k atm. It was noted on my 99 that it was measured at 3 degrees at 390k and owner replaced it as prevanative measures.

I have 200k on my 99 and 200k almost on the 92 300d not changing them any time soon hopefully

IIRC the FSM never mentions correcting the timing chain elongation for the OM603. If it weren't raining right now I would try to check my stretch with the 2mm method myself.

If Mercedes never bothered to mention correcting it you're probably just better off replacing it I suppose.