Recently I read the write-up from Best4x4 on swapping out the mediocre oil separator design for an inline PCV and decided to do it. Everything runs great except when the Disco has been sitting for a while— say overnight— and I start it up, sound from under the hood is loud and seems to be coming from the PCV I installed at the intake. It doesn't sound good at all. If I turn off the engine and restart it right away, it sounds normal every time without failure. My question is: Is that normal for this mod? I used the part from NAPA to get the job done.

 

I've installed a ton of them and none have ever made any noise. It sounds like the valve inside the PCV is sticking. Might be factory defective, what year D2 did you install it on? If it's an 03-04 you have to enlarge the hole at the valve cover side. If you have a D2 with secondary air those make all kinds of sounds at startup.

 

They do not make any noise, but you can check for a sticky PCV valve. Before you start pull the hose and use a small screwdriver to tap the "piston" inside the valve, is should move freely and come back to the same place.

If so it is fine, but to make leave the hose off and startup if you still get noise it is something else

 

Thanks all for the replies. So I've been hammered with work lately and only got to this a few nights ago. Something weird happened: I started hearing a knocking noise from the engine bay that was only audible at idle or low speeds. I pulled over, looked under the bonnet, and saw nothing at first. But to my surprise, one of the hoses from the SAI tube to valve had come undone— I must've not clamped it from the ignition coil job... So I plugged it back in, and reset the engine light that had just come on. After that, I heard no more knocking noise and funny enough I have not had the loud noise at startup either.

Must've been SAI-related, I guess because I haven't touched the inline PCV at all... Can this be the case?