Alternator on kills the oil pressure guage.

[petercstephenson]

Have just purchased SN 129 and we have an electrical problem. After testing/replacing all the piping of the engine:

With the alternator off, the oil pressure switch operates normally. Switch the alternator on and the oil pressure drops to nil which is most disconcerting. We have cleaned out the the oil line to the sender and primed it to be sure.

Also, I have a new battery but with the alternator on, switching on all the electrics (radio, fuel pump, AH, DG, beacon, nav lights etc.), causes the low voltage light to come on.

and I still have to install a Lx Zeus, Powerflarm and transponder!!

Please can you advise how to fix these problems.

PeterS

[petercstephenson]

Have just purchased SN 129 and we have an electrical problem. After testing/replacing all the piping of the engine:

With the alternator off, the oil pressure switch operates normally. Switch the alternator on and the oil pressure drops to nil which is most disconcerting. We have cleaned out the the oil line to the sender and primed it to be sure.

Also, I have a new battery but with the alternator on, switching on all the electrics (radio, fuel pump, AH, DG, beacon, nav lights etc.), causes the low voltage light to come on.

and I still have to install a Lx Zeus, Powerflarm and transponder!!

Please can you advise how to fix these problems.

PeterS

[Thermalseeker]

OP senders are notorious for suddenly going bad or suddenly acting flaky. Change out the sender before you start looking elsewhere. They're relatively cheap (<$30). My low voltage light comes on at 12.2 VDC, IMHO, too high. I haven't looked to see how they did the low voltage light circuit. There's nothing I've found in my manuals about it. Not sure if there is a way to adjust the threshold, but it would be nice to drop it down to about 11.8 VDC or so. Make sure all your connections are tight, especially the ground connections.

[Thermalseeker]

OP senders are notorious for suddenly going bad or suddenly acting flaky. Change out the sender before you start looking elsewhere. They're relatively cheap (<$30). My low voltage light comes on at 12.2 VDC, IMHO, too high. I haven't looked to see how they did the low voltage light circuit. There's nothing I've found in my manuals about it. Not sure if there is a way to adjust the threshold, but it would be nice to drop it down to about 11.8 VDC or so. Make sure all your connections are tight, especially the ground connections.

[eugenio]

Before any change, check all grounds, it seems like you have a bad ground and the sender or the gauge drains current from somewhere. It's the same like when you have your direction indicator light in your car that stops blinking when you brake.

The best is to check the lines from each sender to each gauge and check the sender has a good connection with the ground.

Check also the alternator connections are correct. If the problem come out just after the replacement of the piping, probably you inadvertedly disconnected some wires or damaged a ground connection.

Eugenio

[eugenio]

Before any change, check all grounds, it seems like you have a bad ground and the sender or the gauge drains current from somewhere. It's the same like when you have your direction indicator light in your car that stops blinking when you brake.

The best is to check the lines from each sender to each gauge and check the sender has a good connection with the ground.

Check also the alternator connections are correct. If the problem come out just after the replacement of the piping, probably you inadvertedly disconnected some wires or damaged a ground connection.

Eugenio

[Steve Sliwa]

I was provided an e-mail thread that is occurring in parallel and I will extract contents from the thread and insert below.

Here is the feedback from the factory technical rep:

Hi Peter,

After discussing your problems, this is what we suggest:

- Oil prssure - should be bad sensor grounding. It must be grounded to the same point where the indicator is grounded. Use a metal bracelet or strap at the sensor point and weld an 18AWG wire to it, and then weld or attach the other end real good to the negative pole of the battery.

- The same must be done with the negative wire of the oil pressure indicator, which is to be linked to the negative pole of the battery and attached to the sensor grounding pooint

This, Peter, because these damn oil sensors are very sensitive to ground loops which generate counter-currents, making the indication go to zero; to avoid that, all the wires must be tightly attached to the negative pole of the battery.

Please tell us the results of this long distance trouble shooting.

Best regards,

Claudio

He also added the following comment:

Sorry for missing low voltage with full load problem, Peter. Look again for corrosion or dirt in the connectors, including also the voltage regulator connection. If problem persists, you probably have to replace faulty voltage regulator.

Please inform.

Rgds Claudio

Peter Stephenson replied:

Hi Claudio,

Have checked all the grounding, doing the extra even though it really was not necessary as 0.01 ohm is good.

Have spoken to an electronics fella who thinks it could be a reverse polarity where the increased voltage reverses the current in the oil pressure circuit.

Are you able to supply a new voltage regulator?

PeterS

Here is the feedback from XimangoUSA

Peter,

We have had good luck troubleshooting grounding problems by removing all aircraft wiring connections to the offending gauge or component, reconnecting it using only clip leads ( with alligator clips), assuring that the device works properly with the clip leads making the connections, then reconnecting the aircraft wiring one wire at a time until something goes wrong. It is almost always a loose wire or a bad ground connection in some obscure place.

The Voltage Regulator is a Rotax part and should be available locally. They do not fail often, but it has been known to happen several times in the USA fleet.

Kind Regards,

Chuck Cheeseman

XimangoUSA

[Steve Sliwa]

I was provided an e-mail thread that is occurring in parallel and I will extract contents from the thread and insert below.

Here is the feedback from the factory technical rep:

Hi Peter,

After discussing your problems, this is what we suggest:

- Oil prssure - should be bad sensor grounding. It must be grounded to the same point where the indicator is grounded. Use a metal bracelet or strap at the sensor point and weld an 18AWG wire to it, and then weld or attach the other end real good to the negative pole of the battery.

- The same must be done with the negative wire of the oil pressure indicator, which is to be linked to the negative pole of the battery and attached to the sensor grounding pooint

This, Peter, because these damn oil sensors are very sensitive to ground loops which generate counter-currents, making the indication go to zero; to avoid that, all the wires must be tightly attached to the negative pole of the battery.

Please tell us the results of this long distance trouble shooting.

Best regards,

Claudio

He also added the following comment:

Sorry for missing low voltage with full load problem, Peter. Look again for corrosion or dirt in the connectors, including also the voltage regulator connection. If problem persists, you probably have to replace faulty voltage regulator.

Please inform.

Rgds Claudio

Peter Stephenson replied:

Hi Claudio,

Have checked all the grounding, doing the extra even though it really was not necessary as 0.01 ohm is good.

Have spoken to an electronics fella who thinks it could be a reverse polarity where the increased voltage reverses the current in the oil pressure circuit.

Are you able to supply a new voltage regulator?

PeterS

Here is the feedback from XimangoUSA

Peter,

We have had good luck troubleshooting grounding problems by removing all aircraft wiring connections to the offending gauge or component, reconnecting it using only clip leads ( with alligator clips), assuring that the device works properly with the clip leads making the connections, then reconnecting the aircraft wiring one wire at a time until something goes wrong. It is almost always a loose wire or a bad ground connection in some obscure place.

The Voltage Regulator is a Rotax part and should be available locally. They do not fail often, but it has been known to happen several times in the USA fleet.

Kind Regards,

Chuck Cheeseman

XimangoUSA

[Thermalseeker]

FWIW, when Claudio refers to "welding" above he means soldering. VR's do fail from time to time, usually heat related. Not unheard of, but not that common. Lockwood, CPS and/or LEAF should have them in stock, but hang onto your wallet. They ain't cheap. My experience has been VR's either work or they don't. It's more likely there is a bad ground, bad sender or a combination of the two. It's also possible that the sender wire has fatigued at a crimp fitting on either end. Improperly stripped wires and vibration will do this, even with Tefzel wire. If possible, have someone sit in the cockpit and monitor the low voltage light and ammeter. Have someone else wiggle the sender wire and the alternator feeds. Also check that the connections at the battery relay and the battery are tight and undamaged. If you don't want to do this with the engine running you can check the continuity with an Ohm meter. Be sure the master is off.

[Thermalseeker]

FWIW, when Claudio refers to "welding" above he means soldering. VR's do fail from time to time, usually heat related. Not unheard of, but not that common. Lockwood, CPS and/or LEAF should have them in stock, but hang onto your wallet. They ain't cheap. My experience has been VR's either work or they don't. It's more likely there is a bad ground, bad sender or a combination of the two. It's also possible that the sender wire has fatigued at a crimp fitting on either end. Improperly stripped wires and vibration will do this, even with Tefzel wire. If possible, have someone sit in the cockpit and monitor the low voltage light and ammeter. Have someone else wiggle the sender wire and the alternator feeds. Also check that the connections at the battery relay and the battery are tight and undamaged. If you don't want to do this with the engine running you can check the continuity with an Ohm meter. Be sure the master is off.