In a message dated 7/25/2006 8:31:38 PM Central Standard Time,
jhassall@blacksburg.net writes:
> Related question: does oil actually get to the gauge or is it just
> compressed air? When (if, at the rate I'm going) I fire my engine for the
> first time, how long should it take for the oil gauge to register? Would
> it make sense to prime the line first?
>
Don't bother. I primed my oil line once. It didn't last. Here's what
happens. Each time you stop the engine the oil galley drains and oil is
replaced
with air. The next time you start up the oil from the pump will force some of
this air into the gauge line. Over time, after many start/stop cycles more
air will find its way into the gauge line and being lighter than air, it will
work its way up toward the gauge and your prime will be for naught.
Some of the after market gauges use a nylon gauge line with a very small ID
which can be a good thing in limiting oil flow if the line should spring a
leak. I had one such gauge at one time and noticed that the gauge lag time was
noticeably reduced with a primed line. That is because oil is pretty much
non-compressible and oil did not have to flow though the line portion near the
engine to take up the volume lost by the compression of the air further up.
But
the factory gauges have pretty generous line ID's and gauge lag time, even when
full of air, is not significant.
But remember that pressure is pressure and it doesn't matter if there is oil
in the line or air, the reading will be the same. And if it springs a leak,
oil will come out sooner or later.
Cheers
Dave
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