I just returned from the MB dealership here in San Antone. I picked-up some bolts special ordered from Germany to rebuild the mechanical governor that controls the amount of advance of the injection pump on my 300D (believe it or not, MB only replaces mechanical governors and not rebuild them, cost $504 to $580 to replace versus about $30 to rebuild, I used grade 8.8 bolts bought locally to temporarily assemble the mechanical governor and get my car on the road until the special bolts came in).

The asst. parts manager confirmed that his technicians/mechanics use master links that are crimped with a special tool and that they do not use clip type master links. To aid our discussion the asst. parts mngr. got a timing chain for my 300D and we inspected the master link - it is the crimp type to make an endless chain. I asked him why the MB engine manual I have shows the clip type master link - he did not know why, only that the crimp type master link is stronger than the clip type.

Also, the MB timing chain for the 300D is made by JWIS and these initials/service mark are stamped on the timing chain's side plates. The replacement chain for my 300D purchased from Performance Products is also made by JWIS and comes with a master link that has to be crimped with a special tool that I discussed in an earlier reply. The PP timing chain has a 24 month transferable warranty - the MB replacement chain a 12 month warranty. I have used JWIS chain in the past and they were all equal to the OE chain or better.

Neither the MB timing chain nor the PP timing chain come with a clip type master link - only the crimp type master link requiring a special tool to perform the crimp operation. PP rents the tool for $35 for a two week period plus S&H.

Larry your observation that the clip type master link is used for replacing the old chain by attaching the old chain to the new chain is probably correct (since the MB manual does not say). Like you, I cannot see MB using a clip type master link for continuous service and the clip type link is only used for assisting with the replacement of the old chain to ensure the chains do not become separated and turning a straight forward job into a much more time-consuming repair. I can see the clip type master link being a MB special tool to assist with replacing an old chain.

Michael, your pictures of the timing chain indicate a major failure probably in the oil reaching the chain. The oil lubrication path diagram for my 300D shows that this timing chain is lubricated from outflow from the first bearing journal (the closest bearing journal to the front of the engine) and when I replaced my front crankshaft seal I did not see an oil pipe or oil passage that would directly oil the timing chain. Meaning the timing chain on my engine is lubricated indirectly - which is a method that I have seen on numerous engines Your engine probably uses the same or similar way to lubricate the timing chain - indirect. Your comments about low oil pressure indicates a major failure of some kind (oil pump, failed main journal bearing, cam bearing, some crack or break or blockage in one of the oil passageways, failed oil filter with pieces clogging an oil line/passage, etc., etc.) and will have to be found when you disassemble the engine - as Larry wrote about. I would suggest being very observant as you disassemble your engine and look for the cause of the failure. Finding the real cause of the failure is very important because the cause must be found and corrected before rebuilding your engine - simply replacing broken parts with new ones and then running your engine may/probably lead to the same failure again.

Finding the cause may require more extensive disassembly of your engine than you may want to do or have planned for, but I think you and Larry will agree the cause must be found to avoid a repeat failure costing lots of $. As I recall, you wrote that this engine had been overhauled not too long ago (correct me if I am wrong) leading me to believe that the cause leading to the first overhaul was not found and fixed, or was not fixed completely/correctly.

Your picture of the timing chain shows a chain made with split rollers that fit onto the pin and the picture shows one pin missing a roller. Split rollers do come apart far more easily than non-split rollers. The lack of a split roller coupled with the torn side plate show a probable loss of oil pressure leading to a failure (perhaps stopping the crankshaft or cam from turning) causing damage to the timing chain- as you and Larry have written about. I am sure the chain had the roller when it was replaced (provided it was replaced) and the failure caused damage to the roller and that is why it is missing. One would hope that the people who did the overhaul did not re-use a timing chain that was missing a roller.

An inspection of the pan and the debris (if any) in it will tell a lot. As Larry said, you should remove the pan to see what's in it.

When you rebuild the engine I know you will lubricate the various moving parts that are usually done (pistons/rings/pins, cylinder walls, rods, bearings, cam, valve guides, etc., etc.) - I suggest that the new timing chain be lubricated with engine oil. Simply rotate the engine and pour some oil on the top of the chain, rotate it a bit more and pour more oil on it until the entire chain has been oiled. I have not read any recommendation to oil the timing chain like this before initial start-up, but I believe pre-oiling the chain will extend its life since it is indirectly lubricated. This is how I lubricated my 300D's timing chain before start-up as well as other timing chains on the numerous engines that I have rebuilt - none ever failed.

Michael, I will read with interest as you write about your engine and the cause of the failure.

Good luck!

Tom