E300D 1995 air piston noise

[davidmash]

When the engine is cold there is a noise that sounds like an air pressure piston popping off or a spray can short burst. It is engine speed related. Also, when the engine temp gets to about 50C or so the noise goes away.

I have a suspicion of what it is. Under the the black plastic cover over the valve cover there is black disk looking thing that has hoses coming off of it to each of the intake runners. When I took the black plastic cover off I noticed that one of the hoses was disconnected from that black disc thing. Not sure if I knocked it off or if it came loose.

What is that black thing and the hoses? Is it under pressure (can it blow the hoses off?) or is it vacuum?

If its not this, any other ideas?


Thanks

[Maxbumpo]

That is the PCV valve, and all those tubes should be attached. It is under pressure, routing the engine blow-by into your intake manifold.

The plastic and rubber bits may be old and hardened, so you may need to just replace all those plumbing bits with new, but you can probably keep the valve itself.

[davidmash]

Originally Posted by Maxbumpo

That is the PCV valve, and all those tubes should be attached. It is under pressure, routing the engine blow-by into your intake manifold.

The plastic and rubber bits may be old and hardened, so you may need to just replace all those plumbing bits with new, but you can probably keep the valve itself.

So just to be clear. it is under pressure not vacuum right?