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Re: UrQ low boost pressure
In message <email@example.com> Andrew Finney writes:
> So in the never ending UrQ saga I decided to bite the bullet
> and assess the condition of the turbo. For those who are
> following I now only get 8psi of max boost from my TAP'd '83
> UrQ. Well, after many knuckle scrapings all the hoses were
> removed and........ just a tiny bit of oil coating the hose from
> the turbo to the intercooler, no metal shavings, no grit. Actually
> most of the oil in the hoses was at the other end, near the
> intake manifold.
Oil is normal. Quite a lot, sometimes.
> I grabbed the turbo shaft and there was no
> play at all. The turbine spun perfectly smoothly, no grabs or
> rough spots. Conclusion: turbo is in great shape.
I know I _always_ scream: "Look inside the hose." The reason is not that
it's a very common failure mode - it's that it's very cheap to check and
the potential saving is $$$$. Sounds like you're OK, though.
> So can I test the wastegate by crimping off the pressure
> feed line and carefully accelerate?
Yes, but I would recommend attaching a separate (calibrated) boost gauge.
Don't rely on the dashboard instrument for a test like that.
> Anyone have any thoughts as to why I no longer have full boost?
Will I sleep?
> What about the frequency valve, do these go bad on UrQs?
And affect boost? Not on a WR.
> Checked the line to the VDO boost gauge, it
> holds vacuum so there aren't any leaks in the gauge line. It's
> OK to use the original gauge's feed line right? I had it teed into
> the FTCU line but I prefer this location, but showed 8psi max
> boost. Could the pressure be leaking from the differential lock
> knob, or is there a one way valve to prevent pressurization of
> the diff. vacuum lines? Any thoughts appreciated. Thanks.
Nah. Very hard to imagine a leak from there. And, if so, it only sniffs at it.
If your picture of boost is from the dashboard gauge, and you also feel like
doing a "crimped off" test, then attach a separate boost gauge by tee-ing in
to one of the two parallel inlet manifold take-offs and do the test. Meantime,
let us think.
Committee Member, UK Audi [ur-]quattro Owners Club