Wet vs Dry Vacuum Pump

I am curious of opinions out there. I currently have a wet Vacuum pump on my
Glasair I-RG. I am considering adding an M-20 vacuum pump oil separator just
for the vacuum pump since I also have a Christen inverted oil system separator
which takes care of the Crankcase breather. I am also considering changing to a
dry vacuum pump. I am tired of loosing a quart every 4-5 hours and oil mess on
the belly. What should I do? I do plan to use the plane for some hard IFR, I
will be working on getting my instrument rating this winter. Will the M-20
catch 90% or what percentage. Anyone out there using this M-20 model 600WP unit
for vacuum? at $360.00 I don't want to be disappointed.

If you already have a wet pump (robust vanes, 2000 hr life?), I can't
imagine why you want to switch to a dry pump with average MTBF of 400
hours. I don't know how good the M20 is - Airwolf is another separator
that appears to have a little more robust design, but probably either
will work.

If you already have a wet pump (robust vanes, 2000 hr life?), I can't
imagine why you want to switch to a dry pump with average MTBF of 400
hours. I don't know how good the M20 is - Airwolf is another separator
that appears to have a little more robust design, but probably either
will work.

"Fastglasair" wrote in message
...

I am curious of opinions out there. I currently have a wet Vacuum pump on
my
....
the belly. What should I do? I do plan to use the plane for some hard IFR,
I

Keep the wet pump. If you fly real IFR you need to replace dry pumps every
500 hours. There's a lot of us out here with dry pumps who'd rather have
wet.

-cwk.

On Thu, 16 Dec 2004 04:41:59 GMT, "Colin W Kingsbury"
wrote:

"Fastglasair" wrote in message
...

I am curious of opinions out there. I currently have a wet Vacuum pump on
my
...
the belly. What should I do? I do plan to use the plane for some hard IFR,
I

Keep the wet pump. If you fly real IFR you need to replace dry pumps every
500 hours. There's a lot of us out here with dry pumps who'd rather have
wet.

-cwk.

Got that right, I'd rather have a wet pump. Lets see - longer life,
fewer $ for replacements, more reliable... What's not to like? Some
oil on your belly?

Oh, but don't think that a dry pump will keep your belly clean. It
gets oily etiher way. Stick with the longer-life, more-reliable wet
pump and put in a seperator to catch more oil.

Good luck.



Chuck
N7398W



P.S. -- Lotsa planes loose a quart every 4 to 5 hours, even WITH a dry
pump!!! You should see what some of the training planes at a local
school eat up. What's the old joke about "Fill the oil and check the
gas"

The commentators so far are referring to the excellent advantages of
the wet
pump for IFR.

Far as I know, none of the separators work very well with negative Gs.
I have
a wet pump and the Walker (airwolf now) and if I do a 0 G parabaloa, I
get oil all over the belly.

If you are doing both acro and ifr, the dry pump might be better.
Bill Hale Loveland CO

One thing about oil seperators. They collect water. Water freezes. Then
they don't let the crankcase breathe at all. This is for some
installations, some are in a warm spot. Depends. Keep an eye on it.

From what I understand, not only does the wet pump last MUCH longer,
but when it dies, it dies gradually rather than going belly up while you
are in a cloud, on an NDB approach, one very dark night. I fly hard IFR
and would never give up my wet pump.

Helen