At 11:08 PM 5/20/98 -0500, you wrote:
>Can someone do a good job of explaining exactly how the leak-down
>instrument works?
I'll do my best, but you'll get what ya' pays fer...
>I've seen a diagram, I see that the air supply pressure bleeds
>through a small orifice on the way to the engine cylinder and that
>the pressure of the "supply" is compared to the pressure of the
>cylinder to arrive at the percent of leakdown but:
Yup, that's about it.
>won't the orifice size affect the amount of air available to "leak"?
Sorta - if there's little to no leak, a larger orifice will just
allow the system to stabilize faster. If there's a big leak, a
larger orifice will make it easier to hear where its coming from
<grin>. What you need to keep in mind is that you're measuring
pressures, not volumes of air.
>Is it just arbitrary?
Its not arbitrary, but it is relative; that is, the pressure in
the cylinder has some relation to the pressure in the supply
side which is determined by the relative sizes of the orifice
in the tester and the size of the leak.
>Someone clear me up on this, please!
I hope that helps,
John Lye
rjl6n@Virginia.edu
|