Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

efore switching off: when the engine stops the oil pumps stops immediately. The turbo,
however, may keep on spinning for a few more seconds if the engine was racing just before
being switched off - simply because of inertia. So again the turbo would spin fast with insufficient
oiling. This (and the 1st generation problems mentioned before) is the reason behind the
different 'turbo pre- and post- oiler' systems.
This is also why a synthetic oil is best for a turbo car (bearing (sorry) in mind the drawbacks of
synthetics) - apart from any other qualities they may have, synthetic oils maintain their
properties MUCH better in high temperatures - and while a normal engine normally wouldn't
have such high temperatures in it, the turbo does.
[Response: David Farrington] Basically your "Idling down" is merely sitting at idle for 30
seconds or a minute before shutting down the car. The turbocharger can literally get red hot
during spirited driving. Naturally we don't normally do that, but depending what our drive has
been like - 70 miles at 80 on the freeway is not the same as 5 miles at a steady 25 mph. This
idle time gives the turbocharger time to cool down a bit, both with some water cooling and more
importantly some oil cooling and circulation. One can purchase and install automatic oil timer
pump kits that circulate the oil automatically, but good habits are far cheaper.
First word on owning a turbo engine - change the oil & filter! I'm religious, every 3k miles and the
turbo seems fine at 190k miles although I'm starting to think of a pre-emptive turbo cartridge
replacement.
Gasoline Recommendations for Turbo Engines. See the link to the Fuel and Lubricants file.
[Other related comments:] . I could pick up some pinging on 87 octane when boost was up,
thus switched to 89 and things are much quieter. I'll even go to 92 octane when I know I'll be up
on the boost gage. [Editor] To avoid pinging and lower performance, use the specified 91 or 92
octane gasoline.
Turbo
Maintenance.
Turbo
Components.
[David
Armstrong] See
the photo for a
depiction of
turbo
components.
1 incoming air
Turbo Components