1999 V70T5M reflections on servicing turbo CBV

[abscate]

wotking on the Compressor Bypass Valve (CBV) ( thanks for correcting, Lee!)

This is the valve that sits just in front and below the waste gate valve on the T5 ME7 car. The function of this valve is to excess boost to the intake manifold just in front of the turn.

Just wanted to share my experiences replacing the diaphragm on this with turbo installed.

On the 1999, it's a b*******

I'm in the middle of PCV service and replacing the last hoses on my 1999 before it goes to college.

Working behind the motor is tough and it's tough to get your hands down into the area. Many operations require two hands ...more to come.

Approaching the beast...turbo pipe, cooling hoses removed


Here is the winter of your disconnect....

Bolt number one, 10mm wrenches off easy..you are 1/3 done and sitting pretty.

Bolt number 2, at the bottom, you go underneath since your hand won't fit from top. Note the shiny part of the turbo coolant return pipe. You guessed it...the bolt will not clear the pipe with it installed, so plan on replacing that hose for this job. From below, left hand to start the threads, it is tough moving cover to align but it must be done. Tension bolt number one so that the cover moves but stays in place.

Bolt number 3, tucked behind the heat shield, is the spawn of the Devils seed. You can't get fingers nor tool in from the side, so you approach it from the top with right hand, jockey the cover with left to get the bolt aligned. I actually fed into the hole with a Kelly clamp I stole from surgery.

When you feel the threads catch, rejoice, turn it down, the go up top with your open end 10mm and turn it in , in 1/12 rotation increments, inverting your wrench each time.

Hopefully you won't do what I did, and get the cover on, then look under the car and see your BCV spring and diaphragm fell out and yuk have to remove and replace again. Elapsed time, 3 hours.

[Ozark Lee]

I actually think that is the Compressor Bypass Valve (CBV). It is essentially a Blowoff Valve (BOV) that is a closed loop and returns air to the turbo intake rather than just dumping it.

I've had several turbos on and off and it might just be easier to loosen the turbo from the exhaust manifold to get to the bottom bolt. That said I've not yet tried to change one while the turbo is installed. I have a bad one on the platinum and I need to though.

...Lee

[abscate]

CBV it is.

Can someone with VIDA on a 1999 post the diagram of this system to complete the reference?

It's a little different then the 1998-earlier I think.

[j-dawg]

When I was doing my turbo coolant hose, I had to go from above, and the most comfortable way I found to do it was to climb up onto the engine.

Can't remember exactly how I did it - I have some vague memories of putting my knees on the engine block, and I may have lain on my side at some point - but this kept my hands free to hold and manipulate things while my back wasn't bending over the car.

I am a small person so this might not work for everyone. You have to be careful not to put weight on the fan shroud or on the intake manifold far from the block.

Also, I highly recommend a headlamp for pretty much any job you're not doing outdoors in the sunlight. You'll look like a dork, but aren't we scraping up our hands and emptying our wallets for old Volvos? Bit late to worry about that.

[abscate]

Look like a dork? I'm way past that. MIT students laugh at me when I walk on campus with my contra-rotating dual propeller beanie cap on...

I think climbing on top with headlamp is the way to go but my porker butt would test my new suspension...

[erikv11]

When I was doing my turbo coolant hose, I had to go from above, and the most comfortable way I found to do it was to climb up onto the engine. ...

Affirmative. It is awkward, but this is how I service the CBV diaphragm in-car.

[abscate]

Can you get to the lower bolt from up top? On the 99, I don't think that works. Maybe the water pipe is a little different?

If you remove the water pipe I think this job might be easier but that looked nasty.

[erikv11]

Oh you are right, I don't know the 99s, that pipe is different. That car must have the in-pan oil cooler, too?

[abscate]

Correct. The last two hoses I have to replace on this car are the pan oil cooler hoses.

[j-dawg]

Correct. The last two hoses I have to replace on this car are the pan oil cooler hoses.

How bout the ones under the intake manifold?

Those ones snuck up on me. Didn't replace 'em when I did the PCV. I'm gonna regret it.