Re: Turbos around town

[hugo@knoware.nl (Hugo van der Vlist)]

Joff wrote:

>I only ever had an Audi turbo for a few weeks, but I was unlucky enough
>to own a volvo turbo estate car for three years - 100,000 miles worth. It
>was kept outside, not exactly serviced on time, never given a cool down
>idle and certainly not a warm up period.
>
>It went like shit off a stick all of the time. Absolutely reliable.
>Performance was not as good cold, but that didn't stop me booting it off
>the end of my drive in the morning. Used for commuting and bumming around
>town, not good for a car apparently, but I never had any bother with the
>turbo. An Audi, I'd expect, would be even better.

Well, I wouldn't be too sure about that...
I own an 85 ur-quattro and I live in The Netherlands. I'm a member of the
Audi Coupé Club in the Netherlands, 87 members, of which 27 own a turbo
quattro coupé, or 5000TQC as I guess they're called in the USA.
Most of these TQC owners have had to replace their exhaust manifold or
turbo at least once, which is a known problem on these cars. It seems that
you can expand the time between failures *considerably* if you refrain from
revving the engine over 2500 rpm until it has reached its working
temperature. Also, below 2500 rpm you shouldn't get the turbo to work
(boost) until it is warm.

Why?

The exhaust manifold is a very large piece of iron that needs time to adapt
to the high temperatures. If you don't allow for that, the inside will
expand more than the outside which will make it break. You can drive on
with a broken manifold but you will lose power. It will also start making
noises.
The turbo is a very fine piece of machinery that revs at very high speeds.
It will only do this properly at working temperature. Until that moment
excessive wear will be the result of asking extra boost from the turbo.

Now, when you are parking your car it is the same story. You must let the
engine (manifold) cool down, already during the last miles you drive, but
you must also let the engine idle for a minute or two before turning it
off.

Why?

The manifold will (after some time) crack if you turn the engine off
without cool down, and the turbo will run hot because there's no more
(fresh, cool) oil going through to it. The turbo will burn the oil it has,
which means a layer of burnt oil on the axle and bearings of the turbo. In
the end this will affect performance, and will increase wear.

So, it may seem that all is well now, but this may change in the near future