[mike sevel]

The E90 valve cover has a vent valve diaphragm that cannot be replaced separately. It is an integral part of the valve cover which cost $350+ DIY to $1,000+ full dealer installed. Two aftermarket companies are selling a replacement diaphragm cap on Ebay for$20-$30. The installation requires that the valve cover cap be removed. which is a formidable task since the cap is sonic welded to its base.
One fellow on the net used a Dremel to cut the cap off its base. Result looked rough but he attached the replacement cap with RTV sealant. He claims it improved the former drivability
issues.
I had a suggestion that might result in a cleaner removal of the cap. Campers know of a string saw that is used to cut branches for kindling. Price is $2-$4 dollars. The string saw could make a cleaner cut allowing the replacement cap to fit tight as the pressure is not high in that area. RTV sealant can be added for peace of mind.
Has anyone tried this option?
Pls advise.
Mikey

[ChuckThomas]

You need to use epoxy or solder and abs plastic to seal the crankcase vent valve cover back to the valve cover; not rtv.

[mecheng77]

You are referring to the PCV valve, what makes you think you need to replace it. Did you do the oil cap test?

[mike sevel]

While I was having some O2 sensor issues, I stopped in at a local INDY who services German cars. With the engine running, he removed the oil filler cap with difficulty and the engine was loud. He said I need a new valve cover.
Mikey

[Welcome to NBA Jam]

Watch this video. This is a better way to take the cap off instead of dremeling around it.

[6ixSpd]

I rebuilt mine using the new diaphragm kit. I bought it from that Russian website I can't remember the site right now.

Definitely worth a shot. You have nothing to loose.