hi/lo vacuum alarm adjustement?

[N400YS]

Hi Folks!

 

I encounter some worry with my hi/lo vacuum alarm on a 1995 M20J MSE.

Since the vacuum pump has been replaced, the alarm is showing on! The analogic indicator indicated 4 inch of Hg before replacement of the pump but now the vacuum is 4.5 inch.

When the engine is iddled, vacuum is 4 on the alarm is gone off.

 

Do you think there is a way to adjust the hi/lo vac alarm or I am condamned to adjust the vacuum regulator in order to stay at 4 inch??? (normally the vacuum range is with 5)

 

Thank you for your advises!

 

Olivier

[N201MKTurbo]

The easiest thing is to adjust the vacuum regulator. It isn't hard. I have found that if you adjust your vacuum to the low side of he range your gyros will last longer.

[N400YS]

3 hours ago, N201MKTurbo said:

The easiest thing is to adjust the vacuum regulator. It isn't hard. I have found that if you adjust your vacuum to the low side of he range your gyros will last longer.

You're definetely right!I will adjust the regulator at 4 inch....That will solve the problem and save my gyro's ;-)

 

Thank you very much!

[Guest]

The vacuum switch is not very hard to adjust.  The procedure is in the manual.

Clarence

[N400YS]

 

The vacuum switch is not very hard to adjust.  The procedure is in the manual.

Clarence

Hi

 

Here is the end of the story: The Hi Vac alarm was ON because the adjustement screw is missing.......

 

I fixed the problem by lowering the vacuum waiting for replacing the screw or the whole vacuum switch!

 

By the way, were can I find this part? Could someone give an idea of the cost of this part?

 

Thanks

[carusoam]

How do you know an adjustment screw is missing?  I can't see where one used to be.  Unless the hole in the photo is the spot you are referring to.

Try to be familiar with the list of Private Pilot maintenance work that is acceptable to be done by an owner.

making adjustments to the vacuum system and replacing parts of that system might not be on that list.

If you are sourcing the part for your mechanic to install, your photograph seems to have most of the details you are asking about, and access to the Internet is the other piece.

Typical method for getting a job like this done is as follows...

1) Identify the problem.

2) Explain to your mechanic what you have found.  That you want to source the part.

3) If you want to install the part you can, but the log entry may need your mechanic's signature.

4) The Mooney system to buy parts is simple.  Parts are sold through their network of MSCs.  Call them up, place an order.

Since the vacuum system drives the instruments that keep the clean side up and the dirty side down in IMC, it is unlikely that a PP is legal to make these adjustments.  This is an important system.  Not having the proper background to work on it can be troublesome.  Adjusting the vac system to keep a bad high limit switch satesfied does not sound like a proper solution to the problem.

Somebody posted the list of Maintenace things that a PP can do on his plane around here somewhere.  The search function should be able to unearth it. 

I am a PP, not a mechanic.  The system may be on the list.  I am not that familiar with it.

Best regards,

-a-

[Marauder]

  The vacuum switch is not very hard to adjust.  The procedure is in the manual.

Clarence

Hi

 

Here is the end of the story: The Hi Vac alarm was ON because the adjustement screw is missing.......

 

I fixed the problem by lowering the vacuum waiting for replacing the screw or the whole vacuum switch!

 

By the way, were can I find this part? Could someone give an idea of the cost of this part?

 

Thanks

http://www.sigmatek.com/pages/prod_description/PD_ACC_vacswt.html

Last I heard $400. I replaced mine with the Precise Flight low vacuum indication kit for a lot less.

Sent from my iPad using Tapatalk

[N400YS]

 

How do you know an adjustment screw is missing?  I can't see where one used to be.  Unless the hole in the photo is the spot you are referring to.

Yup, that is the place where I thought that the screw should  be :-) but I am obviously wrong!

 

Don't worry, I just check the problem in order my mechanic solves it.

 

thanks for your advises.

Edited January 9, 2016 by N400YS

[N400YS]

 

 

Last I heard $400. I replaced mine with the Precise Flight low vacuum indication kit for a lot less.

Sent from my iPad using Tapatalk

Thank you. I will talk my mechanic about this precise flight kit if he can't find cheaper for the sigmatek one!

 

 

[Marauder]

   

Last I heard $400. I replaced mine with the Precise Flight low vacuum indication kit for a lot less.

Sent from my iPad using Tapatalk

Thank you. I will talk my mechanic about this precise flight kit if he can't find cheaper for the sigmatek one!

 

 

This is the kit I used.

http://www.thevacsource.com/products.php?cat=2

Sent from my iPad using Tapatalk

[N601RX]

On mine the adjustment screw was the brass screw in the center. There was a second adjustment screw that can be accessed by removing the switch from the dg. It is up inside the inlet pipe.   

It can be disassembled and cleaned by manipulating the 3 indented tangs on the rear. It they are flattened a little the internals will slide out.  

[N400YS]

 

On mine the adjustment screw was the brass screw in the center. There was a second adjustment screw that can be accessed by removing the switch from the dg. It is up inside the inlet pipe.   

It can be disassembled and cleaned by manipulating the 3 indented tangs on the rear. It they are flattened a little the internals will slide out.  

Ok.

 

actually, it seems that I missunderstood the maintenance manual directives!

 

my mechanic will handle the adjustment.

 

thanks

[Mooneymite]

I replaced mine years ago.

I found out that the switch was available from various sources, but at vastly different prices.  I'm sorry, I have no idea of my eventual source.

After I had the replacement switch, I took the bad switch apart to see if it could be fixed.  The first thing that happened was that one of the aluminimum tangs broke off (it appeared that someone prior to me had opened the switch).  Inside was pretty simple, but if the diaphram is busted, you're done.

 

 

[N400YS]

 

I replaced mine years ago.

I found out that the switch was available from various sources, but at vastly different prices.  I'm sorry, I have no idea of my eventual source.

After I had the replacement switch, I took the bad switch apart to see if it could be fixed.  The first thing that happened was that one of the aluminimum tangs broke off (it appeared that someone prior to me had opened the switch).  Inside was pretty simple, but if the diaphram is busted, you're done.

 

 

I think that the diaphragm of mine is ok because the switch reacts for the low vac (flash when the engine is off) and le high vac lights only when the vac is up than 4.5 inch.

Do you remember the direction you have to turn the inside switch screw to increase the trigger vacuum sensibility of the switch in order to adjust up than the present 4.5inch to 5.5? Clockwise?

 

thanks

[Mooneymite]

 

Do you remember the direction you have to turn the inside switch screw to increase the trigger vacuum sensibility of the switch in order to adjust up than the present 4.5inch to 5.5? Clockwise?

No, sorry.

[N400YS]

 

No, sorry.

Never mind :-)

[N601RX]

With a portable vac source, gauge and meter it was pretty easy to adjust both the high and low points.  Without them it is going to take a lot of test runs and trial and error.

[N400YS]

 

With a portable vac source, gauge and meter it was pretty easy to adjust both the high and low points.  Without them it is going to take a lot of test runs and trial and error.

Right!