Valve Cover Gasket Replacement - My C55 is a 2005 and has 52,000 miles. The gaskets on both sides were causing leaks that trailed down the back of the block and terminated near the transmission mount. The breather covers were also seeping oil and making a mess of the valve covers.





I used the following spares for this job;
• Valve cover gaskets - 1130160221, 1130160321
• Mercedes brand RTV sealer – 0039899820/10
• Breather hoses – 1120180182, 1120180282, 1120180382, 1120180482 (1 ea.)
• Hose connectors – 1179901578 (4 ea.)
• Replacement valve cover screw (lost) - 0019908322
• Replacement coil pack screw (lost) - 0019907212
• Replacement breather cover screws (one time use) – 0000004436 (5ea.)
• Replacement coil pack harness connectors – 2035453028 (8 ea.)
• Loc-Tite (for coil pack and throttle body fasteners)
• Brake cleaner / carburetor cleaner (interchangeably)

The underhood heat and age really took a tool on the breather hoses and mine cracked on removal. The coil pack wiring connectors also broke very easily. The trickiest part of this job was removing the breather covers from the valve covers. You will need something softer than magnesium but hard enough to crack the seal. Eventually I used a wooden ruler which I had filed to a bevel edge. The ruler was not much use after that. I also used a plastic pry tool intended for interior trim removal. Now came the tedious part which was removing all the old gasket sealer from both sides of the breather cover interface. I used wooden sticks, a screwdriver and a rotary tool (“Dremel”) with a nylon brush wheel. I also used brake cleaner to clean all the breather orifices and valve cover surfaces. I re-assembled the breather covers to the valve covers using Mercedes sealant and waited a few minutes before mating the parts. I used brand new stainless fasteners torqued to 4Nm. I then installed the valve covers and tightened all fasteners in a radiating pattern to 8Nm.






At this time, I replaced all coil pack harness connectors, using a technique of breaking the old one gently until the individual wires and female spade terminals could be removed. I removed and relocated each wire (from old to new connectors), one at a time, to avoid any errors.




Crankshaft Position Sensor - I replaced this after removing the MAF sensor and throttle body. All breather hoses had been removed too. I lay on top of the motor and accomplished this, sight unseen. I left the harness connected to the sensor, removed the fastener and then pulled the sensor up gently (once loosened) by the harness. I installed the new sensor and used a small screwdriver as a probe to align the hole in the sensor flange with the threaded hole in the engine block. Using both hands (glove size – XL), I avoided dropping the mounting screw and managed to get it started and tightened. This took about 60 minutes, some expletives, and minor loss of blood.

I used the following spares for this job;
• Crankshaft Position Sensor (Bosch from Amazon – 0261210170)


Throttle Body and MAF Sensor Cleaning - the throttle body had a visible but not dramatic amount of build up on the throttle plate, and I cleaned it and the MAF sensor (you will need a security Torx bit #30 to remove the fasteners) with brake cleaner and electronic sensor cleaner respectively. I reassembled these items with a new O ring from Mercedes and a new MAF bracket. The car started and has run fine since with a minor improvement in idle quality.

I used the following spares for this job;
• MAF Bracket – 1121410440
• Throttle Body O Ring - 3059970345

Sorry about the lack of pics - I will try harder next time.

 

Great write-ups! Thanks for posting

 

Glad to have a chance to contribute, ghiaguy! I would not have tackled this job if not for posts by you and others. Motor mounts, transmission mount, and flex discs next...

 

Didnt you post you had 50K miles? are your mounts and flex discs that bad already??

 

My mounts went bad at around 50k, PO drove her hard...

Good to have you on board, DFac!

 

Capn, I have mild vibration from the motor so I would like to just get this job out of the way. With the flex discs, it's 10 year-old rubber so while I have the car in the air...

 

omg just the write up i needed!!
I have to get to my throttle body cause i know there is build up there and my car has been stalling more frequently.
Do you know the torx number to remove the tb fully off the car?

Thank you, greatly appreciated