1999 V70 XC AWD Turbo 2.4 - Blowoff valve diaphragm defective Topic is solved

[wizechatmgr]

So my vac hose diagram on the hood is pretty much useless.

The check is where I can build vac - the 'X's are where I cannot. I'm assuming that the top connection should be the blowoff valve which I cannot build vac on - and the one beneath that is the wastegate - that I can build vac on. The bottom one I cannot build vac on. I'm trying to make sure these are routed correctly so when I go through the pain of replacing them I do it right.

I'm guessing I should test the TCV while I have the vac. pump handy. Can someone assist in identifying the correct connections?

Where would I buy a new blow-off valve diaphragm? I saw some aftermarket japanese on ebay but I know with volvo's most parts are crap that aren't OEM.

Symptoms - sluggish at most RPMs but not unbearably so at high RPM. Rarely if ever hear any turbo whine - usually only when cold and only within the first 3 miles.

[wizechatmgr]

Looking like this is similar - but unsure if it is the correct fit. Still need to wash the turbo down - it has a layer of nasty on it.

http://www.xsboostturbochargers.com/pro ... dge-srt-4/

[bmdubya1198]

I believe the connection at the back (below the electrical connector) is where there is vacuum/boost. That is the hose coming from the turbo compressor housing. The top connection is a signal line to the wastegate, and don't hold me to it, because I'm not entirely sure, but that should only be boost going through there to signal the wastegate to open. The hose on the left side is just a fresh air hose. I don't think any vacuum is made there (again, don't know this for sure. I can check later on).
Which are you talking about being bad, the compressor bypass valve (blowoff valve) or the TCV?
You can find the CBV internals on performance parts sites like ARD Tuning (ardideas.com) if there is a problem with it. They probably have the stock spring if you look around.
From the sounds of your symptoms, you might have a problem with your wastegate (or just the TCV) and not your CBV. If the CBV was stuck closed, you would have the boost hang on after you let off the throttle, which you would definitely notice. I guess you could have your symptoms if the valve is stuck opened, but you would have too look into testing it.

[wizechatmgr]

Sounding like whomever hooked it back up previously likely didn't do so correctly. I only removed one hose and replaced it... I believe the CBV may be bad as I cannot pull any vac on it. I only remove one vac line at a time... Learned my lesson many years ago.

I did these with the car not running in order to check the diaphragms. It is ENTIRELY possible that whomever owned it before didn't hook the hoses up correctly. They likely were done years ago and are the reason I now own it

Going to go out later and give that turbo a good washing after it cools down. Bringing out the S100 and wheel cleaner since it is so bad. Degreaser didn't do anything for it.

[wizechatmgr]

So just thinking this over further. So the CBV runs off the intake manifold (I think it is on the line on the right side)

Suspecting TCV now. Sounding like I should get pressure on it. What is the failure mode for TCV? Does it just stop opening/closing? Is it usually an electrical issue or a mechanical issue?

Found a quick diagram at http://www.vivaperformance.com/pierburg ... -s80-xc90/

[rspi]

[bmdubya1198]

Not entirely sure exactly how they fail, but it's happened. I would double check those hoses and make sure they're connected where they're supposed to be connected.
The CBV should run off of manifold pressure, correct.

[wizechatmgr]

Thanks for all the help all.

~141k miles

Mine doesn't have the idle air control valve but everything mostly matches up. Finally got my turbo somewhat clean on the outside by the intake. Used some S100 I usually use on the bike and it worked wonders. Gunk foamy engine cleaner didn't even come close.

Checked the coil on the TCV for basic continuity and it appears to be good. Looking like that lower boost vac/pressure line off the turbo probably needs to be replaced based upon the condition of the others. All of mine look to be original and crumble if touched. Stage 0 may be a slow process but I feel it is well worth it and will be worth it long term. Cleaned the TCV out with carb cleaner. Didn't appear to be too bad but I feel a slight difference using the seat of the pants test. Will source another one just because of the age.

[bmdubya1198]

Butt dyno is by far the most accurate test .
Order some silicone vacuum hose on eBay. I think there is a thread over on Volvospeed documenting all of the vacuum hoses and their inner diameters so you know what to order. That's how I did it with my TCV hoses, some evap hoses, and other vac hoses, and I'm very happy I did. All of my hoses were nasty.

[wizechatmgr]

RE: replacement vac. hoses -- Yeah, already started that project as you can see above with my dirty red silicone tubing
Been doing about one hose a weekend. Thus far I think I've removed about a total of 3 -5 feet. Not bad considering most of the time it has been bitter cold out, and the other half of the time I've been too lazy.

That plastic PCV hose (it crunched like plastic) that goes around the engine from under the intake manifold around the right side is on the to-do list. I believe I crushed it a few weeks back. Heard a loud snap - then found out that night on the forums it was solid/rigid on the inside. Oops -- time to try that 5/8" heater hose everyone recommends.

The car sat prior to my ownership the entire summer on the lot. No one wanted it - poor car. I drove past it many a time on the motorcycle thinking of it and the fact it wasn't moving. When it came to buy it I just knew it had to be. Had a VW before and figured it couldn't possibly be any worse.