Incorrect EGT Reading?

[crabman]

Finished installing new Isspro EGT & Boost gauges today. I immediately noticed that the EGT gauge was reading 225-250* but the engine has not been started for 3 days. I thought the EGT would read the outside temperature which was about 60*. Also the jumper wire was off the gauge when I took it out of the box. (instructions stated to remove j/w. )

What gives?

Is it the probe or the gauge?

If I disconnet the wires at the probe, what resistence should I read with Ohm meter? Suggestions?

Thanks in advance!!



Crabman

 

[lmills]

Most electrical gauges do similar things when you take a away the 12 volt suply source(turn the key off). When they do not since voltage they drop, but then read OK when you resupply the volotage needed.



I asuming the truck was off when it was giving you these readings?

 

[crabman]

Imills,

There is no external electrical voltage applied to the thermocouple. It makes(?) the voltage (millivolts) by having dissimilar metals connected.



Update:

This morning the gauge was reading 150-175* and the outside temp. was around 60*.

Called Isspro and explained the situation and the best answer was return the thermocouple(probe) and they would check it out. I thought that the thermocouple should read the ambient temperature on a cold engine or close to it.

 

[Thomas]

TDR issue 34 (Nov/Dec/Jan 2001-2002) has an excellent article on EGT gauges.

 

[paccool]

Mine reads whatever the temp is. Was around 60 degrees the other night when working on the truck. Was pretty close to actual.

Mine are US Gear, don't know who made them for US. Is the same as a ISSPRO as far as style and the thermocouple setup.



Stan

 

[illflem]

My Banks pyro (made by Isspro) always read ambient temp till one day cold day I noticed it reading around 200°. Banks said return the gauge, the probes rarely fail, I did, all fixed. Pretty good free service on a five year old gauge.

 

[lmills]

Originally posted by crabman

Imills,

There is no external electrical voltage applied to the thermocouple. It makes(?) the voltage (millivolts) by having dissimilar metals connected.



:

Are you telling me that you didn't have to hook up a 12 volt source to the back of the gauge?

 

[crabman]

Imills,

That is correct. Only 12v is for the lighting.

Check out the article in Thomas's reply.



Thomas,

Thanks for the info!! Great article. Everything you need to know about thermocouples and gauges.



Illfem,

I will contact my seller today and see if I can get a new gauge, nothing to loose. All they can say is NO.



Thanks to all who have answered.

Crabman