[rebel-builders] oil pressure sensor failure

steve whitenect · Post by **steve whitenect** » Sun Feb 19, 2012 4:38 pm

Hi Garry
I have found the UMA gauges inaccurate. My oil temp for instance reads 20* cooler than actual and my oil pressure is also low.

Steve W> Date: Sat, 10 May 2008 08:14:51 -0600> From: wright.garry30@gmail.com> To: rebel-builders@dcsol.com> Subject: [rebel-builders] oil pressure sensor failure> > I have the Westech Mfg. unit(snsor model 387-15 -its TSO'd) in my rebel > - apparently either the sensor or the guage has failed. All the wiring > is intact and the engine does develop pressure - gratefully. The sensor > is $200+ in the US so substantially more here. ACS offers UMA guages and > sensor for less than that.> > 1. Does anyone have a surplus unit they want to sell?> > 2. Any comments on the UMA choice?> > Garry> 068R> > > > -----------------------------------------------------------------> List archives located at: https://mail.dcsol.com/login> username "rebel" password "builder"> Unsubscribe: rebel-builders-unsubscribe@dcsol.com> List administrator: mike.davis@dcsol.com> -----------------------------------------------------------------> > >
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Ken · Post by **Ken** » Sun Feb 19, 2012 4:38 pm

It might be possible to tweak the readings somewhat with an external
resistor. In series to raise the resistance of the sensor or in parallel
to lower it. Nice thing about the Grand Rapids EIS is that you can
quickly tweak the software settings to calibrate most sensors. And they
did indeed need tweaking when I calibrated them.
Ken

steve whitenect wrote:

Hi Garry
I have found the UMA gauges inaccurate. My oil temp for instance reads 20* cooler than actual and my oil pressure is also low.

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Ken · Post by **Ken** » Sun Feb 19, 2012 4:38 pm

Any chance an automotive sensor such as from VDO would match? I think
mine is 180 ohms. I've never found the large bellows type sensors that
move a variable resistor to last a long time Garry. I've seen sensors go
erratic but none have leaked on me yet. The specs should be available to
test your units. ie the resistance of the sensor with no pressure (and
also at full pressure). Measure the sensor resistance to check it. Or
confirm the gauge operation by substituting a resistor for the sensor.

You might be able to find a system that uses a solid state sensor. Quite
possibly cheaper than the Westach as the sensors are around $100. or so.

Ken

Garry wrote:

I have the Westech Mfg. unit(snsor model 387-15 -its TSO'd) in my rebel
- apparently either the sensor or the guage has failed. All the wiring
is intact and the engine does develop pressure - gratefully. The sensor
is $200+ in the US so substantially more here. ACS offers UMA guages and
sensor for less than that.

1. Does anyone have a surplus unit they want to sell?

2. Any comments on the UMA choice?

Garry
068R

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Wayne G. O'Shea · Post by **Wayne G. O'Shea** » Sun Feb 19, 2012 4:38 pm

Garry.. to check if it's the gauge.. take the wire off the sender and ground
it out... the gauge should go full scale if you do that (with the master
turned on). If it does.. it's the sender.

As Ken suggests... good chance the sender from VDO will work fine as well.
Used on the rotax 912 for oil pressure.

----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Saturday, May 10, 2008 1:06 PM
Subject: Re: [rebel-builders] oil pressure sensor failure

Any chance an automotive sensor such as from VDO would match? I think
mine is 180 ohms. I've never found the large bellows type sensors that
move a variable resistor to last a long time Garry. I've seen sensors go
erratic but none have leaked on me yet. The specs should be available to
test your units. ie the resistance of the sensor with no pressure (and
also at full pressure). Measure the sensor resistance to check it. Or
confirm the gauge operation by substituting a resistor for the sensor.

You might be able to find a system that uses a solid state sensor. Quite
possibly cheaper than the Westach as the sensors are around $100. or so.

Ken

Garry wrote:
I have the Westech Mfg. unit(snsor model 387-15 -its TSO'd) in my rebel
- apparently either the sensor or the guage has failed. All the wiring
is intact and the engine does develop pressure - gratefully. The sensor
is $200+ in the US so substantially more here. ACS offers UMA guages and
sensor for less than that.

1. Does anyone have a surplus unit they want to sell?

2. Any comments on the UMA choice?

Garry
068R

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Garry · Post by **Garry** » Sun Feb 19, 2012 4:38 pm

Thanks Steve, Ken and Wayne.

This sender is a 4 wire arrangement of some sort and I don't actually
know how it is wired inside. Being 4 wire suggests rather strongly that
it contains a 4 wire bridge arrangement and one of the legs probably
creates an imbalance when pressure is applied. Resistances in the bridge
with no pressure are 800, 500, 320 and 200 ohms which suggests the
sensor is probably okay.

I then measure the meter which is a six pin configuration and get no
real continuity. It looks like there is a capacitor across several
terminals because the circuit takes an initial pulse of current from an
ohmmeter but has no dc continuity.

Its probably the meter. I will check with westach on Monday I guess.

Garry

Wayne G. O'Shea wrote:

Garry.. to check if it's the gauge.. take the wire off the sender and ground
it out... the gauge should go full scale if you do that (with the master
turned on). If it does.. it's the sender.

As Ken suggests... good chance the sender from VDO will work fine as well.
Used on the rotax 912 for oil pressure.

----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Saturday, May 10, 2008 1:06 PM
Subject: Re: [rebel-builders] oil pressure sensor failure

Any chance an automotive sensor such as from VDO would match? I think
mine is 180 ohms. I've never found the large bellows type sensors that
move a variable resistor to last a long time Garry. I've seen sensors go
erratic but none have leaked on me yet. The specs should be available to
test your units. ie the resistance of the sensor with no pressure (and
also at full pressure). Measure the sensor resistance to check it. Or
confirm the gauge operation by substituting a resistor for the sensor.

You might be able to find a system that uses a solid state sensor. Quite
possibly cheaper than the Westach as the sensors are around $100. or so.

Ken

Garry wrote:
I have the Westech Mfg. unit(snsor model 387-15 -its TSO'd) in my rebel
- apparently either the sensor or the guage has failed. All the wiring
is intact and the engine does develop pressure - gratefully. The sensor
is $200+ in the US so substantially more here. ACS offers UMA guages and
sensor for less than that.

1. Does anyone have a surplus unit they want to sell?

2. Any comments on the UMA choice?

Garry
068R

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Wayne G. O'Shea · Post by **Wayne G. O'Shea** » Sun Feb 19, 2012 4:38 pm

Oh yah.. that's right ! Forgot about that funky plug on that one. I didn't
pick it ! LOL

Other option and a cheaper one might be to ditch the westach all together
and replace with something else as a set.

Wayne

----- Original Message -----
From: "Garry" <wright.garry30@gmail.com>
To: <rebel-builders@dcsol.com>
Sent: Saturday, May 10, 2008 7:24 PM
Subject: Re: [rebel-builders] oil pressure sensor failure

Thanks Steve, Ken and Wayne.

This sender is a 4 wire arrangement of some sort and I don't actually
know how it is wired inside. Being 4 wire suggests rather strongly that
it contains a 4 wire bridge arrangement and one of the legs probably
creates an imbalance when pressure is applied. Resistances in the bridge
with no pressure are 800, 500, 320 and 200 ohms which suggests the
sensor is probably okay.

I then measure the meter which is a six pin configuration and get no
real continuity. It looks like there is a capacitor across several
terminals because the circuit takes an initial pulse of current from an
ohmmeter but has no dc continuity.

Its probably the meter. I will check with westach on Monday I guess.

Garry

Wayne G. O'Shea wrote:
Garry.. to check if it's the gauge.. take the wire off the sender and
ground
it out... the gauge should go full scale if you do that (with the master
turned on). If it does.. it's the sender.

As Ken suggests... good chance the sender from VDO will work fine as
well.
Used on the rotax 912 for oil pressure.

----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Saturday, May 10, 2008 1:06 PM
Subject: Re: [rebel-builders] oil pressure sensor failure

Any chance an automotive sensor such as from VDO would match? I think
mine is 180 ohms. I've never found the large bellows type sensors that
move a variable resistor to last a long time Garry. I've seen sensors go
erratic but none have leaked on me yet. The specs should be available to
test your units. ie the resistance of the sensor with no pressure (and
also at full pressure). Measure the sensor resistance to check it. Or
confirm the gauge operation by substituting a resistor for the sensor.

You might be able to find a system that uses a solid state sensor. Quite
possibly cheaper than the Westach as the sensors are around $100. or so.

Ken

Garry wrote: -----------------------------------------------------------------
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Garry · Post by **Garry** » Sun Feb 19, 2012 4:38 pm

If it is the meter, that is only $77US - probably $150 by the time I get
it here with shipping and brokerage and all that trade barrier crap but
still cheaper than a pair.

Garry

Wayne G. O'Shea wrote:

Oh yah.. that's right ! Forgot about that funky plug on that one. I didn't
pick it ! LOL

Other option and a cheaper one might be to ditch the westach all together
and replace with something else as a set.

Wayne

----- Original Message -----
From: "Garry" <wright.garry30@gmail.com>
To: <rebel-builders@dcsol.com>
Sent: Saturday, May 10, 2008 7:24 PM
Subject: Re: [rebel-builders] oil pressure sensor failure

Thanks Steve, Ken and Wayne.

This sender is a 4 wire arrangement of some sort and I don't actually
know how it is wired inside. Being 4 wire suggests rather strongly that
it contains a 4 wire bridge arrangement and one of the legs probably
creates an imbalance when pressure is applied. Resistances in the bridge
with no pressure are 800, 500, 320 and 200 ohms which suggests the
sensor is probably okay.

I then measure the meter which is a six pin configuration and get no
real continuity. It looks like there is a capacitor across several
terminals because the circuit takes an initial pulse of current from an
ohmmeter but has no dc continuity.

Its probably the meter. I will check with westach on Monday I guess.

Garry

Wayne G. O'Shea wrote:
Garry.. to check if it's the gauge.. take the wire off the sender and
ground
it out... the gauge should go full scale if you do that (with the master
turned on). If it does.. it's the sender.

As Ken suggests... good chance the sender from VDO will work fine as
well.
Used on the rotax 912 for oil pressure.

----- Original Message -----
From: "Ken" <klehman@albedo.net>
To: <rebel-builders@dcsol.com>
Sent: Saturday, May 10, 2008 1:06 PM
Subject: Re: [rebel-builders] oil pressure sensor failure

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Garry · Post by **Garry** » Sun Feb 19, 2012 4:38 pm

Wayne,

Turns out the guage/sensor combo, although of the same part number as
current production is of different and obsolete manufacture. It is four
wire and the current unit is 3 wire, thus because the meter is ratched,
the sensor is ndg for anything.

What would you have chosen for the application?

Garry

Wayne G. O'Shea wrote:

Oh yah.. that's right ! Forgot about that funky plug on that one. I didn't
pick it ! LOL

Other option and a cheaper one might be to ditch the westach all together
and replace with something else as a set.

Wayne

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