Sigma trek dry pump question

[Loogie]

My M20J has a Sigmatek dry pump, I have been seeing the low vacuum caution light flashing at me intermittently during flights. Does the pump itself have an adjustment? Or is this an indication of impending pump failure? The filter after the pump is a Rapco filter and I can't find when it was replace or if it ever was. Could that be causing the problem? Also at idle 1100 or below the low vacuum lights is flashing continuously and unless I bump it to 1300 or so, it flashes. Any suggestions other than just replacing the pump and the filter? This plane does not have a vacuum gauge, just a caution light (steady for high and flashing for low)What protocol do A&Ps follow for a similar problem? Thanks for any info in advance!

[N201MKTurbo]

If the filter gets dirty it makes the vacuum go higher.

 

There is no adjustment on the pump. The adjustment is on the vacuum regulator. The regulator is on the inside of the firewall where the vacuum line goes through.

 

If your vacuum is low, it could be the pump, but not likely, they usually work perfectly until they quit.

 

Check to make sure there are no leaks and that the exhaust line isn't blocked.

 

Although re-adjusting the regulator can get the vacuum back in spec, that is just putting a band-aid on the problem.

 

If all you have is the lights I would get a vacuum gauge to see what the real level is.

 

When you say the filter after the pump, do you mean the main instrument filter, or has someone installed a filter between the firewall and the pump? If so that filter could cause low vacuum.

[Marauder]

My M20J has a Sigmatek dry pump, I have been seeing the low vacuum caution light flashing at me intermittently during flights. Does the pump itself have an adjustment? Or is this an indication of impending pump failure? The filter after the pump is a Rapco filter and I can't find when it was replace or if it ever was. Could that be causing the problem? Also at idle 1100 or below the low vacuum lights is flashing continuously and unless I bump it to 1300 or so, it flashes. Any suggestions other than just replacing the pump and the filter? This plane does not have a vacuum gauge, just a caution light (steady for high and flashing for low)What protocol do A&Ps follow for a similar problem? Thanks for any info in advance!

I have a SigmaTek pump as well. I have both the light (which I think is the remnant from the Precise Flight standby vacuum system) and the gauge. I am pretty sure my light is on at low RPMs. Not sure how low, but somewhere around 1000 RPMs. I also note a low vacuum reading on the gauge (just below the green band)

I do not however see the light flicker in flight or the gauge outside of the green band. I change my pump out around 500 hours. Not because of the pending failure concern anymore (I have Aspens) but from the inconvenience of losing the required vacuum driven AI required to back up the Aspens.

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[cliffy]

I have Sigma Tec also with 980 hrs on it.I'm waiting for it to fail any time now :-)

My low pressure light is on also at low rpm but I have no flashing light at any time.

Get a gauge on it and see what it is doing.

[Loogie]

If the filter gets dirty it makes the vacuum go higher.

 

There is no adjustment on the pump. The adjustment is on the vacuum regulator. The regulator is on the inside of the firewall where the vacuum line goes through.

 

If your vacuum is low, it could be the pump, but not likely, they usually work perfectly until they quit.

 

Check to make sure there are no leaks and that the exhaust line isn't blocked.

 

Although re-adjusting the regulator can get the vacuum back in spec, that is just putting a band-aid on the problem.

 

If all you have is the lights I would get a vacuum gauge to see what the real level is.

 

When you say the filter after the pump, do you mean the main instrument filter, or has someone installed a filter between the firewall and the pump? If so that filter could cause low vacuum.

By filter I mean the Rapco filter on the picture. It says to replace when the pump is replaced or 500 hrs, not sure how long mr Rapco has been on the airplane.

Will address those suggestions with the mechanic.

[philiplane]

That is a really old vacuum pump. Best to replace it with the newer style with cooling fins and install a new filter at the same time. Filters should be changed every 500 hours or no more than 5 years. Many are placarded for two year intervals

[Loogie]

Thanks Philiplane will do just that!

[Loogie]

Replaced vacuum pump and is now running great! I have a bunch of trips scheduled including Yellowstone and am confident with the new pump! I also changed the oil and filter:) while cowl was off!

Thanks for the advice guys!