Vacuum Pumps

[Ron McBride]

I have been noticing that my vacuum gauge at idle, is only showing 1 or 2 inches, Horizon is not showing level.  The low vacuum light is on sometimes.

At 1500 rpm, the gauge shows about 5#'s of vacuum.

The existing pump has about 400+/- hrs. on it.   Is the pump screaming, replace me??

Thanks Ron

[Guest]

I'd say yes, that is what it's saying.  If you replace it now, it's cost you about $1.00 per hour.

Clarence

[Ned Gravel]

Clarence:

I have noticed similar readings.  Can you look?

[Guest]

7 hours ago, Ned Gravel said:

Clarence:

I have noticed similar readings.  Can you look?

Hi Ned,

Will do.

Clarence 

[tony]

Other things you might want to consider:

• When was the last time you changed your vacuum air filters?
• Is your Brittain system working correctly with no leaks?
• Have you added anything new that uses vacuum?
• when was the last time your vacuum pump was changed?

[Ron McBride]

Filters at every annual, last August.  Brittain system removed years ago, no new vacuum instruments, and last changed April of 07, about 450 hrs. ago for me. Had regulator turned up last August, seems to be getting worse.

Ron

[cctsurf]

34 minutes ago, Skmoore63 said:

Sounds like it needs to be replaced - but just curious if anyone replaces the vacuum pump at a certain number of hours or years in service?

 

Note that I'm not an IFR certified pilot, but I'd like to be.  I've thought about it a lot as I see people replacing vacuum instruments with electric ones or glass panels.  If I were heavily relying on my gyro instruments and flying to minimums on a regular basis, I would want to have my vacuum pump replaced on a regular basis.

I think there is evidence that this happens because every year in the fly market at Oshkosh there are a number of operational, but used vacuum pumps.

[1964-M20E]

you will hear the recommendation to replace them every 500 hours.  Sound like yours is talking to you.  If you are mechanically inclined and have mechanic that will work with you change it yourself and learn some new words.

 

 

Edited June 13, 2016 by 1964-M20E

[PaulB]

4 hours ago, 1964-M20E said:

you will hear the recommendation to replace them every 500 hours.  Sound like yours is talking to you.  If you are mechanically inclined and have mechanic that will work with you change it yourself and learn some new words.

 

 

Get the special wrench and you'll use fewer dirty words.

[Browncbr1]

I've understood that vacuum pumps have a rather high infant mortality rate so, I would replace at a certain time unless it is giving weak or erratic vacuum readings.  Just my $0.02

[jonhop]

Hmm, this post got me thinking... I can't find in my logs where my pump has been replaced since the last engine overhaul almost 1100 hours ago... I'm wondering if a failing vacuum pump can be the cause of my KAP-150 autopilot porpoise issue. My J's KAP-150 is solid on the ground and the A/P won't fail while connected to test equipment but the system intermittently--definitely uncomfortably--oscillates vertically in the air more often than naught. I'm waiting to hear back from my avionics technician on the subject but it's been a couple of weeks and no word since I posed the question. Anyone else experience autopilot issues due to a failing vacuum pump? It seems logical because the vacuum pump drives the AI, which drives an analog A/P...

[Oldguy]

12 hours ago, jonhop said:

Hmm, this post got me thinking... I can't find in my logs where my pump has been replaced since the last engine overhaul almost 1100 hours ago... I'm wondering if a failing vacuum pump can be the cause of my KAP-150 autopilot porpoise issue. My J's KAP-150 is solid on the ground and the A/P won't fail while connected to test equipment but the system intermittently--definitely uncomfortably--oscillates vertically in the air more often than naught. I'm waiting to hear back from my avionics technician on the subject but it's been a couple of weeks and no word since I posed the question. Anyone else experience autopilot issues due to a failing vacuum pump? It seems logical because the vacuum pump drives the AI, which drives an analog A/P...

Just a thought, but my KAP 150 had the same symptoms when I had water in the static line. Would go from level to 500 fpm down to 700 fpm up. Of  course it first showed itself over a thick layer of clouds over the Gulf of Mexico between Florida coasts. Draining the static lines cleared it up. Would be great if yours was a simple fix like that as well.

[Pictreed]

If you take out the vacuum system when going all electric, can you install a pump for just the step?  Or does the PC system have its own pump?  Just curious. 

Tim

[1964-M20E]

The PC system does not have it's own vacuum source as far as I know.   I do not see any reason you could not leave the vacuum pump for the step alone.

 

Left to my own devices if I were removing the vacuum system for flight instruments I would put an electric actuator on the step and use the vacuum pad for a backup alternator.  But then again we need to deal with the FAA and we could not easily make our aircraft more redundant and reliable without their blessing.