Fast Idle 8V92

[Scott Forman]

Dan,

The other comments about cooling, building air pressure, etc, are
correct, but the main reason is this:

The pistons on the 8v92 are cooled from the bottom by oil, a little
spurt sprays up on the bottom. When at low idle, the pressure gets
very low and will not spray enough oil up on the piston. If you idle
in this situation long enough, it will burn your piston. It's
certainly not going to happen in 10 minutes of idling, but you wouldn't
want to idle overnight.

On my coach, the high idle will not engage until the air has built to
about 30psi, I assume this is where the air throttle starts working.
At start up, I click it on as soon as I hit to 30psi mark and leave it
on until I am ready to get underway. At shutdown, I engage it again
until the temps have fallen to an apropriate level to turn off the
engine. I also engage it any time I am stopped for anything longer
than a stoplight.

Actually, I could leave the switch on all the time, the high idle will
only activate when the parking brake is set. But I am anal and prefer
to do it manually.

Scott Forman
86 PT38 8v92
Memphis

--- In WanderlodgeForum@yahoogroups.com, "maureyroad"
wrote:
>
> Would someone comment on when to use fast idle on 8V92 and when not
to
> use it and why? Thanks
> Dan
> 88WB38
> Jackson, MS
>