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Vans EGT gauge not working...

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mburbidg(at)gmail.com
Guest

Posted: Fri Jun 06, 2014 7:16 pm Post subject: Vans EGT gauge not working...

My Vans EGT gauge does not work. Not flying yet, but have done engine start. And after a few minutes the EGT gauge is still pegged at 0. The CHT gauge does work. These gauges are hooked to a single cylinder. Its a brand new gauge and sender.



Here's what I've done so far:



1) Verified power and ground to the gauge.

2) Verified continuity in the sender wires between the gauge and the space connectors.

3) Verified that the sender wires are on the correct terminal on the gauge.



I'm not sure what to do next, but I would like to figure some way to determine if the problem is with the gauge, or the sender.



How would I do that?



Michael-

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Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Fri Jun 06, 2014 7:45 pm Post subject: Vans EGT gauge not working...

I don't know much about Van's EGT. However, the analog EGT gauges such 

as Alcor did not begin to register until temp got somewhere around 

800-900 degrees. You won't get there with taxi power, but might with 

some leaning get there at runup power. You don't say what engine it is 

one. For carbureted engines it really isn't important. For fuel injected 

engines you really need an analyzer for all cylinders.



On 6/6/2014 8:15 PM, Michael Burbidge wrote:

 	  Quote: 	
		   



 My Vans EGT gauge does not work. Not flying yet, but have done engine start. And after a few minutes the EGT gauge is still pegged at 0. The CHT gauge does work. These gauges are hooked to a single cylinder. Its a brand new gauge and sender.



 Here's what I've done so far:



 1) Verified power and ground to the gauge.

 2) Verified continuity in the sender wires between the gauge and the space connectors.

 3) Verified that the sender wires are on the correct terminal on the gauge.



 I'm not sure what to do next, but I would like to figure some way to determine if the problem is with the gauge, or the sender.



 How would I do that?



 Michael-

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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

mburbidg(at)gmail.com
Guest

Posted: Fri Jun 06, 2014 7:56 pm Post subject: Vans EGT gauge not working...

Carbureted engine. Taxi power only. So maybe it is working.

Thanks

Michael

Sent from my iPhone

 	  Quote: 	
		   On Jun 6, 2014, at 8:44 PM, Kelly McMullen <kellym(at)aviating.com> wrote:

 I don't know much about Van's EGT. However, the analog EGT gauges such as Alcor did not begin to register until temp got somewhere around 800-900 degrees. You won't get there with taxi power, but might with some leaning get there at runup power. You don't say what engine it is one. For carbureted engines it really isn't important. For fuel injected engines you really need an analyzer for all cylinders.

> On 6/6/2014 8:15 PM, Michael Burbidge wrote:

> 

> 

> My Vans EGT gauge does not work. Not flying yet, but have done engine start. And after a few minutes the EGT gauge is still pegged at 0. The CHT gauge does work. These gauges are hooked to a single cylinder. Its a brand new gauge and sender.

> 

> Here's what I've done so far:

> 

> 1) Verified power and ground to the gauge.

> 2) Verified continuity in the sender wires between the gauge and the space connectors.

> 3) Verified that the sender wires are on the correct terminal on the gauge.

> 

> I'm not sure what to do next, but I would like to figure some way to determine if the problem is with the gauge, or the sender.

> 

> How would I do that?

> 

> Michael-

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racerjerry

Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY

Posted: Sun Jun 08, 2014 3:50 am Post subject: Re: Vans EGT gauge not working...

 	  Quote: 	
		  1) Verified power and ground to the gauge. 

	




As far as I know, power to simple analog EGT/CHT indicating systems are for internal lighting only.



First of all, itâ€™s much easier to test the EGT system by removing the sender from the exhaust system and heating the tip with a propane torch to see if you get needle movement â€“ need another person in the cockpit to watch gauge.  Please use some precautions here so as to not burn your airplane nor anyone elses down.  A fire extinguisher AND a handy 5 gal bucket of water along with common sense can work wonders.



If that didnâ€™t work, the next thing to do is reverse the wires and recheck.  Yeah, I know, color code, yadda yadda â€“ Reverse the wires, reheat and see if needle moves



If that still donâ€™t work, disconnect wires from the gauge and check for continuity at the wires.  By measuring the wires, you are checking the sender and any extension leads and eliminating everything except the gauge.   



My Westach setup says sender resistance should be about 2.5 ohms for EGT, but meter lead resistance will add to this, so correct reading will be higher.  You are really looking for continuity at this point.  Now if all appears to be roughly correct, you could turn your digital meter to the millivolt scale, reheat the EGT probe and watch for a tiny millivolt output within seconds of applying flame.



The gauge itself can be checked for continuity with a DIGITAL ohmmeter (the gauge is so sensitive that an analog meter can burn the darned thing out). 

Let me repeat - Test gauge using ONLY a digital ohmmeter



Again, you are just looking for continuity, but Westach says somewhere between 8 & 15 ohms.



Resistance readings may differ as EGT systems may use either J or K type thermocouples (sender), but you are mainly looking for continuity.  These things generally either work well or not at all.



Any resistance in the system or any corrosion will generally result in no or very low indication

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_________________
Jerry King

RnJCurtis(at)charter.net
Guest

Posted: Sun Jun 08, 2014 7:05 am Post subject: Vans EGT gauge not working...

 	  Quote: 	
		  

 As far as I know, power to simple analog EGT/CHT indicating systems are 

 for internal lighting only.



 First of all, itâ?Ts much easier to test the EGT system by removing the 

 sender from the exhaust system and heating the tip with a propane torch to 

 see if you get needle movement â?" need another person in the cockpit to 

 watch gauge.  Please use some precautions here so as to not burn your 

 airplane nor anyone elses down.  A fire extinguisher AND a handy 5 gal 

 bucket of water along with common sense can work wonders.



 If that didnâ?Tt work, the next thing to do is reverse the wires and 

 recheck.  Yeah, I know, color code, yadda yadda â?" Reverse the wires, 

 reheat and see if needle moves



 If that still donâ?Tt work, disconnect wires from the gauge and check for 

 continuity at the wires.  By measuring the wires, you are checking the 

 sender and any extension leads and eliminating everything except the 

 gauge.



 My Westach setup says sender resistance should be about 2.5 ohms for EGT, 

 but meter lead resistance will add to this, so correct reading will be 

 higher.  You are really looking for continuity at this point.  Now if all 

 appears to be roughly correct, you could turn your digital meter to the 

 millivolt scale, reheat the EGT probe and watch for a tiny millivolt 

 output within seconds of applying flame.



 The gauge itself can be checked for continuity with a DIGITAL ohmmeter 

 (the gauge is so sensitive that an analog meter can burn the darned thing 

 out).

 Let me repeat - Test gauge using ONLY a digital ohmmeter



 Again, you are just looking for continuity, but Westach says somewhere 

 between 8 & 15 ohms.



 Resistance readings may differ as EGT systems may use either J or K type 

 thermocouples (sender), but you are mainly looking for continuity.  These 

 things generally either work well or not at all.



 Any resistance in the system or any corrosion will generally result in no 

 or very low indication


	




        Just one other thought on this.  If you added an extension

        wire to the probe MAKE SURE that you used the proper wire.

        If it is a "J" type, Red and White wires, be certain that you use

        the red and white thermocouple extension wires.  Use of other

        wires can give you gross errors.



        Roger

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jun 08, 2014 8:53 am Post subject: Vans EGT gauge not working...

At 06:50 AM 6/8/2014, you wrote:

 --> AeroElectric-List message posted by: "racerjerry" <gki(at)suffolk.lib.ny.us>

 > 1) Verified power and ground to the gauge. 

 > 

 As far as I know, power to simple analog EGT/CHT indicating systems are for internal lighting only.

     Van's line of analog instruments are built on

     a common frame of circuitry used to position

     pointers over approx 250 degrees of arc on

     the dial.

 [img]cid:.0[/img]

     An exemplar instrument (ammeter) was examined

     in our shop some years back . . .

  http://tinyurl.com/mpx8hze

     This particular device was found to be rather sensitive to

     strong fields of radio frequency energy in

     the cockpit . . .

 First of all, itâ€™s much easier to test the EGT system by removing the sender from the exhaust system and heating the tip with a propane torch to see if you get needle movement â€“ need another person in the cockpit to watch gauge.  Please use some precautions here so as to not burn your airplane nor anyone elses down.  A fire extinguisher AND a handy 5 gal bucket of water along with common sense can work wonders.

 If that didnâ€™t work, the next thing to do is reverse the wires and recheck.  Yeah, I know, color code, yadda yadda â€“ Reverse the wires, reheat and see if needle moves

 If that still donâ€™t work, disconnect wires from the gauge and check for continuity at the wires.  By measuring the wires, you are checking the sender and any extension leads and eliminating everything except the gauge.   

 My Westach setup says sender resistance should be about 2.5 ohms for EGT, but meter lead resistance will add to this, so correct reading will be higher.  You are really looking for continuity at this point.  Now if all appears to be roughly correct, you could turn your digital meter to the millivolt scale, reheat the EGT probe and watch for a tiny millivolt output within seconds of applying flame.

 The gauge itself can be checked for continuity with a DIGITAL ohmmeter (the gauge is so sensitive that an analog meter can burn the darned thing out). 

 Let me repeat - Test gauge using ONLY a digital ohmmeter

     Not true . . . the non-electronic instruments designed

     to read millivolt levels DIRECTLY from a heated thermocouple

     have VERY low winding resistance as matter of necessity . . .

     as panel instruments they are generally designed for

     full scale indication with only tens of millivolts

     applied to the terminals at TENS of milliamps. "Self powered"

     instruments of yesteryear were often calibrated assuming

     thermocouple lead wires long enough to reach to the extreme

     engine locations on a large airplane. Lead wires for closer

     engines could be shortened and the lost-resistance

     compensated for by inserting a "thermocouple spool

     resistor" in one lead.

     The resistor was shipped with some too-large value (about 10 ohms

     as I recall). The installing technician could remove the

     cover and peel off turns of wire on the spools underneath

     the cover until the desired calibration was achieved.

 Again, you are just looking for continuity, but Westach says somewhere between 8 & 15 ohms.

     The input terminal to a Van's EGT will be considerably

     higher resistance. Signal conditioners inside the instrument

     are designed for insensitivity to total loop resistance

     of the thermocouple signal . . . this is goes to the

     goal of allowing thermocouples to be extended by any

     practical length without concern for instrument

     calibration as described above.

   Bob . . .

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