High Right EGT and Cylinder Head Temps

[Hockeystud87]

Hello I have a weird scenario with my plane. I seem to have gauges that all read high temps on the right side of my engine. I have the old cylinders that give cylinder head temps not coolant temperatures. EGT's are reading the back two cylinders. I have synced the carbs and my prop is pitched about as close as I think I can get it.


Gauge Readings
Rotax 912 UL 1992 (stock)
5100 RPM cruise
5200 RPM (climb out 65mph)
90mph ish cruise
Back Right Cylinder 206 F
Front Left Cylinder 178 F
Back Right EGT 1550 F
Back Left EGT 1460 F
Oil in 200 F
Oil out 235 F
All #'s are at 5100 rpm Cruise

So I understand the front cylinder and back cylinder head temps being different. I assume that is due to the air temp difference from front and back. The EGT is a little different. What I did discover is that the EGT probes are in slightly different spots.

EGT location on the back left seems to be .25"-.5" further away from the exhaust port of the cylinder. Plus it's on a slight bend where the other side seems to be on a flat and in direct line of the exhaust. I have included pictures of the two sides. The one on the bend is the LEFT side lower temp reading EGT. The total distance from the cylinder head, not the flange, is 2in. This seems close over all.

Are my engine temps reading different just due to the right side probe being slightly closer and in direct line of the exhaust? My grandfather noted this same issue many years ago so it's been a persistent situation.


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[PaulSS]

I would certainly put the probes in the same location or else you're not necessarily comparing apples and apples.

Another thing to try is swap your right side spark plugs with the left and see if that changes anything. If you're not burning the fuel properly because of a dodgy plug then you'll end up with higher EGTs from that cylinder.

Timing good?

[rv9ralph]

Proper placement of EGT probes according to the Rotax Installation Manual available online at Rotax-Owner.com, is: "Readings of EGT taken approx. 100 mm (3.93 in) from exhaust flange connections."

CHT is usually cylinders 2 and 3, which is left forward (2), right rear (3).

Hope this helps.

Ralph