Vacuum Pump Failure

Banjo33

Banjo33

Line Up and Wait
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Banjo33
Both of my vacuum pumps were replaced with overhauled units ~ 5 yrs/200 hrs ago. One failed on my way to drop off for annual at the end of July, the other failed on way home from a trip today. After searching around, it sounds like I should have gotten 500+ hrs out of them. Does this seem about right (on the low end) for the longevity of overhauled dry air pumps? I don’t turn my props backwards and filters are getting changed every Annual. If this is abnormally low, is there something that could be causing premature wear/failure? This is on a PA-30 (IO-320’s).

*not removing the vacuum system as I need it for my autopilot
*not interested in upgrading to a wet pump
 
Anyone washing the engine down with solvents?
Love your anticipatory, beat-down-the-silly-answer in advance maneuver!
 
No, no engine washes. At least not in the last 3 yrs.

Yeah, I figured those questions/comments would come up, so I preempted them!

*no, I won’t trade it for a Bo. (Forgot one, lol)
 
I had a pump fail after 100 hours.
Went to a specialist for the plane. He said this is often caused by either to much suctioning or clogged/dirty lines.
Not sure which issue I had, but I put two hundred hours on it before selling and the new owner has at least 200 more hours since then. No issues so far....

Sent from my SM-J737T using Tapatalk
 
Sounds like the overhauled units are good for about 200 hrs.
 
Silvaire said:
Sounds like the overhauled units are good for about 200 hrs.
Click to expand...
The ones I put on the Aerostar are overhauled and have 400 hours and still going strong per the current owner. (I called to ask, really cool older gentleman)

Sent from my SM-J737T using Tapatalk
 
A lot of times when they fail some carbon gets sucked back into the line due to the residual vacumn in the line when the pump fails. Replace the suction line when installing the new pump as any debri in the line will shorten the life of the new pump.
 
Banjo33 said:
Both of my vacuum pumps were replaced with overhauled units ~ 5 yrs/200 hrs ago. One failed on my way to drop off for annual at the end of July, the other failed on way home from a trip today. After searching around, it sounds like I should have gotten 500+ hrs out of them. Does this seem about right (on the low end) for the longevity of overhauled dry air pumps? I don’t turn my props backwards and filters are getting changed every Annual. If this is abnormally low, is there something that could be causing premature wear/failure? This is on a PA-30 (IO-320’s).

*not removing the vacuum system as I need it for my autopilot
*not interested in upgrading to a wet pump
Click to expand...

The overhauled pumps are your answer. A new unit I typically see over 1000 hours.
 
I've had the polyurethane shear coupling fail and there was nothing wrong with the pump. New shear coupling was $14 IIRC.
 
If the bore of the pump has chatter marks in it, no matter how minor, the new vanes and rotor won't last long. The overhaul kit instructions warn about that. Chatter marking is common enough.

A new pump, with the vane wear inspection provision, can be more economical than an overhauled non-inspectable pump. It can be replaced before it fails, saving inconvenience and vacuum system contamination, and it will last longer, saving shop costs.
 
I’ve R&R’d several over the years with ASSCo parts.
Maybe they will last longer, but I always do it at 500hrs.
 
Salty said:
Maybe you need an AOA
Click to expand...

Heck yes I do! Although my personal limits currently have me operating out of fields that I can afford to be 5-10 mph fast in the flare.

But first I’ve got to figure out why I only got 200 hrs out of two pumps. Guess I’m going to just spring for one of those Tempest Tornado’s (new) and hope it was just shoddy overhauls on the two bad ones.
 
The vacuum pump in my C150 is the one that was in there when I bought it, which was 250 hours ago. I don't believe it was newish when I bought the plane either.
 
Are you hosing down your engine with cold water to make hot starting easier?
 
The Tempest pumps are the way to go, guys. I have installed numerous Tempest and Rapco pumps; both have the vane wear indicating provision so that you can periodically check the wear. Tempest recommends the initial inspection at 600 hours and every 100 hours thereafter, and it works. This way, you're not replacing or overhauling the pump every 500 hours or $ome $illy thing like that, and you're not risking flying it until it breaks in an effort to save money.

Rapco has an oil seal to keep oil and solvents out of the pump. Tempest uses a completely enclosed drive that doesn't let fluids in at all, and has a special flange gasket that lets any oil seepage from the engine's pump drive out the bottom but prevents solvent spray from getting in. I prefer the Tempest. Their inspection port is also a better and more robust design, IMHO.

By replacing pumps when the indication says to, I have never had any pump I installed fail.
 
Banjo, your result is not surprising. I too had a vac pump fail in under the warranty hour limit but past the year limit.
The reason is in the cheap Chinese plastic used for the vanes or coupler. Plastic gets brittle over time.
It explains why the warranty on vac pumps is usually in the range of 1000hrs/1yr. That says "our pumps will run for at least a thousand hours but the materials won't last but a year".

Dan, thank you for the insight, that helps. I had to replace my pump last year and bought a Tempest so I am hoping that it won't quit anytime soon. :)
 
A new Tempest Tornado is in the mail. Hopefully this one will give me a little more life than the last two!
 
Another thing: When the pump's installation instructions say that you are to use NO sealant on the fittings, they mean exactly that. Any sealant that gets into the pump is going to wreck it. And don't clamp the pump body in a vise, either. The mounting flange part can be, if you're careful, but clamping the barrel is just asking for trouble.

Manufacturers go to great lengths to write up and publish instructions and manuals for mechanics. Those who don't read that stuff somehow think they're wasting time to do so, yet I have learned a great deal from reading manuals and instructions. They not only make you think, they save the customer and everyone else a lot of money and headaches.
 
We got 1,100 hours out of a new Tempest dry pump, and while it was getting a bit weak, it still worked when we proactively replaced it recently.
 
It was dead.
 

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Had a vacuum pump failure this morning, in the pattern.

I lived. ;) :)
 
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