1997 850R Change CBV membrane

[gswede]

Ordered me a new mitsu cbv membrane. Its been sitting on the shelf a couple of months - as I accumulated strenght to start the job.

Took me 1,5 hrs including some swearing.

Off with the OTE pipe and airfilter/turbo hose. Also took off exhaust shield for better access.
All in all not to bad a job.
Found holes in my old membrane 170k miles worth of use..

some pics

[rspi]

What exactly does that do? Send the boost pressure reading to your instrument?

[gswede]

It is the diaphrame for the recirculation valve. Open under vacuum and when you get off the throttle, to maintain turbo spinning you need to relieve the excess pressure in front of the throttle plate as it closes. Under boost, the spring is assisted with the positive boost pressure onto the back of diaphrame to keep it shut. Basically it is a bypass valve to let pressurized air back in front of the turbo, that way you dont stall the turbo everytime you come off the throttle or change gears

[rspi]

Thanks, how did you know that you needed to replace yours?

[northernlights]

Here's a couple hints!

https://www.matthewsvolvosite.com/forums ... 66#p319366

https://www.matthewsvolvosite.com/forums ... =1&t=62671