In article <wcqdnYjFfIaf_-TanZ2dnUVZ_uqvnZ2d@giganews.com>,
"David T. Ashley" <dta@e3ft.com> wrote:

> Honda Shadow VT600.
>
> 36 degrees out.
>
> Went the 2 miles up to the coin-operated car wash to wash the salt off.
> Waited for the bike to cool, then sprayed and brushed it down good.
>
> Started it. Walked away for 30 seconds, came back and noticed that the oil
> pressure indicator was on (did not notice if it ever went out). Stopped the
> engine immediately.
>
> Started the engine again, and noticed that the oil pressure indicator went
> out immediately. Stopped the engine to verify that the indicator came back
> on (it did).
>
> Started the bike and rode home. I got the salt off pretty well!
>
> What would cause the oil pressure indicator to come on (besides oil
> pressure)? Could spraying down the bike cause this?
>
> Will check the oil on the next warm day (car wash was a bad place to do it).
> I'm 99% sure it is OK, as I've never noticed a leak and it was filled
> correctly at the last oil change.
>
> Thanks.

Since your motorcycle engine was only idling, it is possible that it
didn't suffer any ill effects. Consider how an oil pressure sensor
works: There's a diaphragm that flexes. Behind it is a spring and an
electrical contact. As the engine warms up, the spring changes its
characteristics slightly, so it may be more or less sensitive to low oil
pressure when it's cold than when it's warm. Moreover, the difference
between oil pressure light on and off is close to the engine's very slow
idle speed, and it's not a certification instrument. All it can tell you
is that if it lights up at speed, the engine has suffered damage.

The way the electrical contact works is that whatever's connected to the
sensor gets grounded when the oil pressure drops ... or when the contact
is shorted to ground by salt water. But I doubt that there would ever be
enough salt water for long enough to keep the pressure light lit for
that long, so I don't think that's the cause.

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
Ten Steps to Fascism: http://www.guardian.co.uk/usa/story/0,,2064157,00.html