RobertR728

Hello
2014 c300 w204 3.5 v6
The diaphramm on the rear of the passenger side cylinder head is bad and causing the engine to squeal and chirp at idle when it's hot. Found that the oil fill cap has hella suction on it when idling. Remove cap and restart cart and squeal is gone but the suction at the fill cap is off the charts.

So I guess my question would be off anyone has changed this diaphram that is on the rear of the cylinder head on this 3.5 engine?
It seems difficult because it's location is so close to the fire wall.

Just wanted input from anyone that has dealt with this issue.

Thanks
Robert

TimC300

I replaced mine last year. It wasnt that hard, just take your time and go slow.

I bought and used a 5/16 offset wrench specifically for the bolts since sockets wont fit. Think i dropped a bolt once while doing it but luckily it feel right to the ground since I happen to have the under covers off under the car.

i replaced the cover and the oil drip pan. Oil drip pan is reverse thread.

I ended up having to go back like 3 times to snug the bolts up because it was leaking oil a little. Cant get a torque wrench in there.

RobertR728

Very nice. If it’s not crazy I’m going to takle it once the April rains stop. Thank you so much for the info Andy the pictures.

TimC300

On mine there is a ground strap running right over the cover than I had to move out of the way, there is one clip towards the MAF i think i removed then pushed the ground strap down.

I decided to replace mine for preventative maintenance but ended up looking fine. hardly any wear on the surface of the drip pan where it fits into the cover. Yours may be worn if your hearing it squeeking.

The breather hose (1 in the photo) just pulls off the cover. My hose had oil in it so to clean it I removed the MAF and elbow below it the hose is clamped to. It was worth it with the amount of oil i cleaned from in there.






I also decided to remove and clean the drivers side breather cover. In my case it turned out to be useless, it wasnt really dirty/oily and there are no parts that move or wear inside it. I was able to simply clean everything with dish soap and warm water and put it back, the gasket was fine.

RobertR728

Awesome info.
This is going on my hit list for this summer vacation. You don't wanna know how I have it rigged now so it won't squeal.

Thank you again for all the info and pictures

cvx5832

Go for it. Super easy indeed.