Problems with Rapco dry vacuum pumps.

Just a warning for those who might consider purchasing Rapco dry vacuum
pumps. Make sure that your engine does not leak oil. If there is any
chance of an oil drip onto the Rapco vacuum pump it may eventually stop
working. The connecting shaft is vented to air. But if some oil drops
on the shaft it may get sucked into the pump and after the oil dries it
may seize the pump. I puchased a 216CW new pump from Spruce and after
20 hours of use it does not work. After returning it to Rapco they said
it was "oil contamination" and not eligible for warranty service, but
offered to replace it at a discount. They really ought to have a better
seal there to prevent the problem.

If you were really smart you would have ditched your pump and installed
the Aeon pump instead. More expensive than the normal dry pump but the
next best thing to a wet pump.



abripl wrote:
Just a warning for those who might consider purchasing Rapco dry vacuum
pumps. Make sure that your engine does not leak oil. If there is any
chance of an oil drip onto the Rapco vacuum pump it may eventually stop
working. The connecting shaft is vented to air. But if some oil drops
on the shaft it may get sucked into the pump and after the oil dries it
may seize the pump. I puchased a 216CW new pump from Spruce and after
20 hours of use it does not work. After returning it to Rapco they said
it was "oil contamination" and not eligible for warranty service, but
offered to replace it at a discount. They really ought to have a better
seal there to prevent the problem.

...you would have ... installed the Aeon pump instead
Actually I removed the vac pump and went to all electric - saved some
weight. But I do think that Rapco or any mfg should prevent something
like that with a seal.

Did you check the Aen pump for oil drip problems? Do they warranty
against oil entry?

Rapco can't put any serious seal on that pump that would last any
time because it's a dry pump, and seals need some lube. Rapco does have
a pump to fit the under-nose mountings like the O-200, where oil tends
to get into the pump, and that pump has a flinger and a drain port to
keep oil out.
Washing the engine with solvent can also wreck the pump. It
needs to be covered during spraydown.
We use Rapco pumps exclusively on five airplanes, and have no
trouble at all reaching 1000 hours.
Basically, your oil leak need fixing. Oil leaks represent an
attraction for dirt, which does no engine any good, and they're a fire
hazard. And some oil leaks are warnings to fix something before it
blows off completely and all the oil is lost overboard in flight.

Dan

Rapco can't put any serious "seal" on that pump...
... [They have a]... pump has a "flinger and a drain port" to keep oil out...
I don't care what its called - it should be on there. Is the
manufacturing cost of such feature so significant? I don't recall any
warnings that came with my new Rapco pump about simple oil drip hazards
or about a special pump model required. I only found out when warranty
service was denied.

...Basically, your oil leak need fixing.....
No kidding. But while you are trying to fix it or if you are unaware of
oil leaks you take a flight risk with the pump. Engines can START
leaking and ruin these "sensitive" pumps. A lot of homebuilders, like
me, have initial leaks until they are found and fixed - its not a lack
of trying.

This post is a warning to others about the risk they may take with such
pumps - unless they are 100% sure their engine does not leak and never
will leak. Even if they find/fix the leak quickly they will not know if
the pump is OK, since the pump tends to work for a while after oil gets
in there.

"abripl" wrote in message
oups.com...
Rapco can't put any serious "seal" on that pump...
... [They have a]... pump has a "flinger and a drain port" to keep oil
out...
I don't care what its called - it should be on there. Is the
manufacturing cost of such feature so significant? I don't recall any
warnings that came with my new Rapco pump about simple oil drip hazards
or about a special pump model required. I only found out when warranty
service was denied.

...Basically, your oil leak need fixing.....
No kidding. But while you are trying to fix it or if you are unaware of
oil leaks you take a flight risk with the pump. Engines can START
leaking and ruin these "sensitive" pumps. A lot of homebuilders, like
me, have initial leaks until they are found and fixed - its not a lack
of trying.

This post is a warning to others about the risk they may take with such
pumps - unless they are 100% sure their engine does not leak and never
will leak. Even if they find/fix the leak quickly they will not know if
the pump is OK, since the pump tends to work for a while after oil gets
in there.


Any good mechanic can find an oil leak its not that hard.

I agree with you. I am in the vacuum pump business, and I don't
understand why they can't make the pump a little more reliable. I can't
change the pump design myself, because it is certified the way it is.
It would be to costly to redesign it. If you need any vacuum pump
assistance, you can call me at 800-621-2531. Good luck to you. Ron

rons321 wrote:
I agree with you. I am in the vacuum pump business, and I don't
understand why they can't make the pump a little more reliable. I can't
change the pump design myself, because it is certified the way it is.
It would be to costly to redesign it. If you need any vacuum pump
assistance, you can call me at 800-621-2531. Good luck to you. Ron

I would bet that any seal material or design that might work,
if it exists, would be so expensive that the pump price would rise just
enough that it would lose its competitive place in the market. Or if
there WAS a suitable seal, someone would have incorporated it by now
and marketed their pump as a superior, new and improved, longer lasting
oil- and solvent-proof design. Rapco HAS made small changes to their
pumps, things that weren't part of the original certification, such as
cooling fins, the inclusion of a small amount of salt in the vanes to
absorb a small amount of moisture and increase the vane life (low
humidity increases vane wear), and the flinger/oil drain idea for the
Continental vertical mount. Such changes lead me to believe that the
ideal shaft seal isn't available or affordable.

Dan

What I have learned from these posts is that dry vacuum pumps are a lot
more problematic than just the oil leak - as per
http://www.casa.gov.au/airworth/aac/PART-1/1-098.HTM link. Its too bad
that there is not more warnings before purchase instead of "wonderful"
features. The one hard to find link is hardly a help for a homebuilder.
I have perused these newsgroups frequently during building process and
there is hardly anything mentioned about inherent dry vacuum pump
problems. EAA has homebuilder vacuum systems help article
http://members.eaa.org/home/homebuilders/building/instruments/A%20Gyro%20Instrument%20System_%20(Your%20Options) .html#TopOfPage
with no operational warnings mentioned as in first article. I suspect,
Dan, that you are not a builder but either a certified plane pilot or
A&P making a living from repairs.

I have eventually replaced the vacuum system with electric for about
the same price and saved weight and expect a lot less problems.

I suspect,
Dan, that you are not a builder but either a certified plane pilot or
A&P making a living from repairs.

Close, but not quite:
-Canadian Aircraft Maintenance Engineer (AME) M1
-Commercial Pilot, Instructor rating
-Homebuilder: building or restoration projects have included
Taylor Monoplane, AMF-S14, Jodel D-11. Auster VI restoration project.
-Since 1972 in homebuilts, flying since '73

I currently spend most of my time in the shop maintaining
aircraft, but make no extra money from doing more work. I work in a
College-based flight training program and teach a class on Aircraft
Systems; between the maintenance and the teaching I have plenty of
reason for research into aircraft problems. When I'm not doing that I'm
flying, either to figure out some problem, or with a student, which
isn't too often anymore, or in the Jodel.

What's your experience?

Dan