[Mercedes Mechanix]

Subject: 1994, Mercedes S420 119.9712.

Problem: Nosey ticking, rattle and becomes much worse with acceleration. The idle is smooth and consistent. Engine has not coded and further inspection has revealed lubricant has baked with both cylinder head, valve train/ cam lubricant areas. This was qualified during further explanation by the owner/driver with the history profile provided.

1. Have positioned the crank at 45 degrees before Top Dead Center (45 deg BTDC).

2. Pulled both head covers (valve assy. covers)

3. Removed TIMING CHAIN TENSIONER

4. To remove all four cams and inspect lifters. WIP on Passenger side presently.

4a. After removal of passenger intake and exhaust cams and noted hydraulic lifters (16 presently) collapsed (+2mm) from norm.. ordered and received 32 OEM Mercedes hydraulic lifters. Images of removed lifters below, new OEM lifters also included for comparison... side by side helps with viewing difference.... cams were not under much valve spring pressure at all! Reinstallation will show a dramatic difference in pressure and engine performance! A huge difference!

4b. The cams must be removed with EXTREME CAUTION! These are extremely expensive and fracture and crack easily. I always start with the center Cam Bearing Tower and alternate from left to right moving toward each end of the cam. This may take a few extra moments to relieve the valve spring tension on the cam evenly, but this is extremely important to ensure undue stress is NOT placed on any of the bearing journal machined edging! The installation is also tedious and involves the same alternation fastener installation process! Again, this to ensure undue stress
is not placed on your expensive cam. Take your time!

We will follow-up with further images as time allows!

Oh yes, Timing Chain looks very good, we scoped via the upper cover and viewed all guides as in serviceable condition. Also did an inspection of the cylinder walls via spark-plug orifice and no scoring is noted, other than expected for 167k miles. The T-chain (chain only) was replaced 15k ago, was R/R by the owner.... qwner referred to this as normal maintenance per her decision.... we give Major kudo's and great work... to this owner after she personally inspected the original T-chain. There were a couple of worn links evident. She pulled the passenger Head Cover and checked while manually rotating the crank clock-wise. Great follow up by this concerned Owner, well, we only assisted with some verbal advice! We do wonder if she is a member of Benz-World yet? She has alldatadiy.com and uses it!

She asked for this assist.. only due to other obligations at this time.

Dietrich

The original lifters (16)removed as of this date, have been checked and have collapsed by just over 2mm. All are totally gummed up with crystal hydro-carbon.... WIP on the remainder 16 lifters on the drivers side...

FYI, per this Owner, this engine had been inspected by a local Dealership's Service Department and no problem was found.

The Owner stated that she was advised by the Dealer Service Writer...
"allow their Service department to give the engine a thorough "Engine Flush" with their "special product" and that annoying ticking will be corrected!