[patrolpilot]

Originally Posted by Ernie Martin

For PatrolPilot: did the Aircraft Spruce type K probe work with the original factory gauge? The original is a type E (which I believe has one lead grounded) and I was under the impression that a type K won’t work with the original gauge.

Ernie, yes, it is working. I've been at Center Line Aero (PKV) the last several days, let me talk to Lou about these probes if you don't mind as he might shed some light on them as he keeps a variety of probes in stock.

Honestly, I would think that the difference between the two lead lengths would necessitate a difference between the two.

Originally Posted by edasmus

I spoke with both Alcor and Universal on the phone and they were both very helpful. From what I understood, there is a resistance difference between the old Alcor 86156 and the new Universal probe. They both agree the Universal probe will cause needle movement on our old Cessna EGT gauges that I believe you and I have the same units in our 1973 C337G models. My old Cessna EGT gauge has adjustable pointers so I can align them after leaning which makes any changes during cruise obvious.

Originally Posted by The C336 Skymaster Story

To aid in identifying a failed engine" Charlie Tanner's power plant group designed a microswitch assembly that sensed fore and aft engine motion in the rubber engine mounts. With a rearward motion (from the drag of the windmilling propeller) a red warning light would illuminate in the related propeller knob. Although the aforementioned microswitch unit multiplied the actual engine movement by a factor of six, there were still false warnings that would prompt an unwarranted engine shut-down. Thus the system was removed in favor of pilot reference to engine and EGT gauge indications of power failure.

You kind of hit the nail on the head. The only thing this gauge is supposed to do, the why behind its installation, is indicate that the engine is hot or cold. We are flying, the only, that I can think of, twin-engine piston airplane where the AFM or POH requires EGT to be used to identify an engine failure.

• The three identifiers
• RPMFuel Flow
• EGT

Give the location of the single probe, after all the exhausts stacks join, I think it is a real mistake to use this instrument to define anything related to peak EGT operations. I know Cessna covered its use for leaning with a paragraph, but the single probe has a lot of promise for compromising a cylinder.

The adjustable knob on my left EGT managed to stop having any effect. I suspect that the gearing inside is plastic, so it just shows full scale hot or cold. The Insight G4T is Primary EGT replacement, and I'm kind of considering pulling the gauge completely. I notice that passengers tend to look at it with that front side full "hot."

I started flying the P337G in 1975 out of Harlingen for Air Central, a 135 Operator, with a majority of our flights into Mexico. My training and advice were to use Fuel Flow for engine management and keep the EGT pointers "near" together for aesthetics.