diagnosing a no-boost situation

Post by **sanfelice** » 18 Dec 2016, 12:48

Before I bemoan the possibility that I blew the turbo on the 2000 V70R, what can I do to diagnose? \

There is no boost. I have a boost gauge installed and it does not get much past "0" which makes me think it's the whole enchilada, but what are the other possibilities before I consider a complete replacement?

Would a torn bypass diaphragm cause a no-boost situation or is that a different symptom?

Thanks.

Post by **Ozark Lee** » 18 Dec 2016, 14:23

If the tear in the CBV is big enough it will behave as you describe. I would pull the intake snorkel off and see if the turbo spins easily and smoothly. If so, pull a vacuum (it doesn't have to be a big deep vacuum, a few pounds is good enough) and see if it holds.

...Lee

Post by **sanfelice** » 19 Dec 2016, 10:52

Thanks, Lee, I will try that first.

Post by **abscate** » 19 Dec 2016, 13:09

Any codes pending or check engine light

The Turbo Control Valve (TCV) on these cars gets tired at about 100k and a new one ($75 or so) will put some spring back into your step.

Replacing the CBV on my 1999T5 was mechanic-hell. Very bad access unless you take a lot of stuff off that is exhaust and rusty.

Post by **scot850** » 19 Dec 2016, 13:35

To replace the CBV on a 2000 'R' requires the turbo to be pulled to get access to the cover bolts. One is hidden right behind one of the coolant metal hoses and there is not sufficient room to undo the bolt fully. I'd look at the TCV particularly if you are running more boost than standard. As abscate rightly says, the TCV has a finite lifetime, and when it fails it prevents the turbo boosting. Check the CBV by removing the vacuum pipe at the TCV and pulling a small vacuum on it and see if it holds. If it holds a vacuum, the TCV is the most likely culprit. The sandard part is only good to about 12-14 psi.

Neil.

Post by **sanfelice** » 19 Dec 2016, 13:48

Thanks, Neil and Abscate, I will try to do that. For some reason I thought I replaced the CBV but that must have been in another car.

It's about 25F here now, so not sure when I can do this. Driving the car with no boost is certainly... interesting.

Post by **matthew1** » 19 Dec 2016, 14:32

Cracked intercooler causes 0 boost situation. I have a few posts about that when it happened to me. I'm on mobile so searching I'll have you do.