2003 3.0i M54 DISA Valve Oil Residue and Seal Question

[özgür evren]

Hi, I recently got a Z4 2003 3.0i with M54 engine and yesterday I have removed the DISA valve for a check if it is loose and needs replacement. DISA valve seems OK but I could not be sure the condition of it. Photos are attached.

There is quite amount of oil residue on the valve flap and the air intake itself.

Looking at the photos, your experience and opinions are much appreciated:

1-) Should I change the o-ring seal around the base of the DISA valve flap?

2-) Is this sticking oil residue normal? If not normal, where should I look?

Thank you

 

[Smartbear]

Hi, that’s normally a sign of a failing ccv system.
Rob

 

[patriot66]

I agree with Smartbear. My DISA had a light oil residue before I replaced the CCV system. Your car is a 2003, the same as mine; and a lot of the plastic and rubber in the engine bay will be perished or brittle. Whilst replacing the CCV you can also take the opportunity to change the inlet manifold gasket, oil filter housing gasket, cam cover gasket etc. In your top photo you can see the infamous convoluted rubber tube (with the hose clip) that perishes and causes air leaks. It doesn't look too good either !

 

[NickDE]

Does the flap itself spin/wobble freely on the shaft ? This is the usual failure mode of the DISA valve. If so you need a rebuild kit. You can also check the vacuum seal is working - turn the flap by hand, then put a finger over the small hole at the bottom of the unit. The flap should then only return to half open, and then pop back fully into position when you take your finger off the hole. Google DISA Valve Rebuild and you will find videos that explain this better than I can.
You should ideally change the orange O ring. A replacement comes in the rebuild kits. The old one is moulded in and you have to scrape it out. I would at least put some kind of sealant on the old one before putting it back.