1997 Volvo 850 T-5: Can you help me identify this part?

[DigiHound]

Hey all,

I posted a couple weeks ago about problems with my 1997 Volvo 850 T-5. Long story short, I'd been told that there was a vacuum leak at the turbo. Several people here recommended I check the vacuum hoses, but the problem wasn't in the hoses themselves.

The shop I took it to over the weekend identified the source of the problem with a smoke test. The leak is coming from the following location (posted as an attachment below)

Specifically, the leak is at the triangular plate. I have heard before that it might be possible to replace the plate with a cover, because my car is an automatic rather than a manual, and that this would stop the leak. I'm not very car savvy, however, and would appreciate advice now that I've isolated which part actually has a problem.

[abscate]

You need a new Compressor Boost Valve ( CBV) diaphragm under that plate. You can't just remove the part that is leaking - the valve is needed to suppress boost when you close the throttle . Im not sure what would happen if you took it off, but I suspect a boosted engine not under load will not be a pretty sight nor will it run very long.

Thread on my 1999, which I think is very similar, below

https://www.matthewsvolvosite.com/forums ... ve#p371782

[Acknar]

That is the compressor bypass valve, or CPV, yes there is the option for a blocking plate, but you will need to install an external valve.
Here is the information page from IPD.
http://www.ipdusa.com/products/10007/12 ... -off-plate

[DigiHound]

Well, is installing an external valve cheaper than installing a new turbo? Because I guess that's what I'm looking at here.

[RussB]

I replaced mine, bought the Mitsubishi part from ebay

https://www.matthewsvolvosite.com/forums ... =1&t=64873

[rspi]

Actually that is a vacuum (really boost leak) at the turbo. Why would you need a turbo replacement to fix a leaking diaphragm?

[Sommerfeldt]

If memory serves, I told you what that part was. Also, still wondering why you think your transmission (automtic/manual) would play a part in this - I think I told you to forget about that.

RussB's thread tells you everything you need to know about changing the diaphragm - why would you switch out a good turbo when this little part of it is leaking? It would be like doing an engine swap because your radiator's bad.

- S

[abscate]

Well, is installing an external valve cheaper than installing a new turbo? Because I guess that's what I'm looking at here.

100 bucks, couple hours for the CBV from IPD.

Turbo 1000 bucks, 8 hours or more if/when exhaust bolts snap off.

Not a difficult one to choose...

[DigiHound]

Keep in mind, I'm not a car person. I'm qualified to change tires, check fluids, and I could work my way through an oil change -- but this is all new to me, and I've never even tried this work before. If I have seemed uncertain, it's because I've had multiple shops making multiple predictions about what might or might not be wrong.

I'm going to have to pay someone else to fix this -- I've been hoping that if I knew what the problem was and how to fix it (at least in theory) when I took it to the shop, I could avoid getting taken to the cleaners by an unscrupulous mechanic (I don't know anyone who does this kind of work and so have to take a crapshoot with Yelp reviews and whatnot).

[Sommerfeldt]

There's no need to pay someone to fix the CBV. Get a new Mitsubishi part, like the one in RussB's thread, and then you dive into it yourself. With these cars, you can do almost everything yourself, as long as you're proficient enough to change tires, oils and fluids yourself. They're delightfully straight forward for the most part. The CBV is in a tight spot, but since you know how to change your fluids, take off the coolant hose, and it should be possible to get in there.

See this thread for some pictures of the job: https://www.matthewsvolvosite.com/forums ... =1&t=38338

- S