EGT problems

[Ou Man]

I recently installed EGT’s on my 503. Everything seemed OK until my last flight when the EGT readings on the back cylinder(nearest to the prop) started playing around. As we all know, the EGT does not react immediately and “warms up” gently. After full throttle on takeoff the readings were normal. I also had normal readings on straight and level. However, as soon as I came back on the throttle the back EGT reacted very fast and dropped down to temps equivalent to idle. The moment I applied throttle, it shot up again…….very similar to what you would expect from a revcounter.
Because the EGT is not and direct electrical instrument, this really puzzles me.
Any suggestions???

[Tobie]

I few years ago one of my EGT's started doing an opposite but similar scenario during a flight. At the time I did not know much about EGT's other than knowing what they usually indicate when flying. On this flight I noticed a different reading than normally on one cylinder and it would change drastic from acceleration to cruise to closed throttle. I recall it giving a lower reading (richer) when full throttle and climbing or hotter (leaner) when cruising or closing the throttle. Engine otherwise performing perfect.

Turned around to airfield for inspection and could'nt find the fault at first until I noticed a tiny small patch of oil on one cylinder head. Took the covers off and whala, one of the cylinder head bolts broke off. It was still nicele seated where it belonged but broken off. Replaced stud and gaskets and all fine since, thanks to egt's, even to a novice at the time.

[Ou Man]

Contacted Aviation Engines. They had a suspicion that the gauge was packing up. Swopped the wires to a spare single EGT gauge and whalla…..no more funny readings. Thanx to Aviation engines.
Will have to replace the duel gauge. Anyone got one lying around?
Dankie Tobie vir jou insette. Waardeer dit baie.

[nickjaxe]

EGTs normally react very quickly.

Nick.