CHT gauge problems

[pierre smith]

Mornin' guys,
My Van's CHT gauge or probe appears to have gone TU. The needle swings all the way to the end of the redline then back to zero and so on. Is there a way to test either the gauge or the probe? Ditto the EGT.

Thanks in advance,

[Mike S]

First, check for loose connections, or a wire shorting to ground.

Full needle swings usually result from either an open, or shorted circuit.

Mike

[gasman]

Originally Posted by pierre smith

Mornin' guys,
My Van's CHT gauge or probe appears to have gone TU.
Ditto the EGT. Thanks in advance,

Two gauges not working? I would guess they have a common ground. And that ground is bad. Each gauge needs it's own ground. And a GOOD ground.

Do not jump from gauge to gauge with the ground. There is resistance in each connection. The gauge reads resistance. Resistance from the sender and does not want to see resistance from bad connections, but will show them as bad readings.

[Bob Axsom]

For general function testing of these temperature sensing devices I use a heat gun. I recently installed a 4-probe EGT from EI (not one of my wisest investments really - the instrument is fine but the need is questionable and reading and remembering numbers with a lag instead of immediate and continuous "thermocouple in the fire" driven analog needle for leaning is a step backward in man-machine interface function) with terminations reversed on their cable. I turned a heat gun on the suspect exhaust pipe for a few seconds and the cooler temperature display on the instrument instantly verified the reversed wiring problem. The instantaneous full swing changes in your case do indicate an electrical continuity problem to me as well.

Bob Axsom