912 overheat suggestions
in 912 / 914 Technical Questions
8 years ago
I have a Rotax 912 engine, with adjustable prop. The engine is about 4 years since new, about 1500hrs.
I was climbing out(prop full rpm, engine dropped back a little from full power) with my CFI on a check ride and about 1500ft agl(1600ft msl) with outside temp around 80f the CHT began to rise near 260f, the oil temp was following it by about 20f or so. I have a 253F coolant temp sensor and it did not go off. We level out and temps were not dropping. We did a 180 back to the airport cutting throttle back increasing airspeed to 110kts or so did not cool it appreciably. Cutting to idle, gliding back upon landing the temps had lowered. Went back to the hangar to check coolant level, etc. Everything looked good. Did a couple of laps in the pattern(up to 800agl) and similar symptoms persisted. At this point it had Evans waterless coolant, the coolant was flush and 50/50 replaced it as per mechanics recommendation.
Another day, temperature inversion 75f or so on the ground 90f at 1500agl. Climbing out at around 1800ft agl CHT to about 255, Coolant light goes on and oil temps around 240f or so. Leveled off and turned around again, cooled down on power-off approach. Did a couple of laps around the pattern, at around 700agl, it would heat up. I have been climbing out 75kts when I would like to be around 65kts. Straight and level flight at 90kts did not lower the temps
One person got out of the plane to lower weight, and tests repeated with similar issues. Performance is fine and can climb pretty much at book before beginning to overheat. I am sure temps would continue to rise if power wasn't cut and would rise much faster if climbed at Vx.
Fresh gas, Sport plus oil, sensors checked out, new plugs 30hrs ago, Radiators looks clean/fins straight, all cylinder heads approx same temperature when cowling removed. Engine runs and idles as other 912 I have flown.
Mechanic is not a Rotax expert and is out of ideas and there are no Rotax specialists at the field.
Thanks
I was climbing out(prop full rpm, engine dropped back a little from full power) with my CFI on a check ride and about 1500ft agl(1600ft msl) with outside temp around 80f the CHT began to rise near 260f, the oil temp was following it by about 20f or so. I have a 253F coolant temp sensor and it did not go off. We level out and temps were not dropping. We did a 180 back to the airport cutting throttle back increasing airspeed to 110kts or so did not cool it appreciably. Cutting to idle, gliding back upon landing the temps had lowered. Went back to the hangar to check coolant level, etc. Everything looked good. Did a couple of laps in the pattern(up to 800agl) and similar symptoms persisted. At this point it had Evans waterless coolant, the coolant was flush and 50/50 replaced it as per mechanics recommendation.
Another day, temperature inversion 75f or so on the ground 90f at 1500agl. Climbing out at around 1800ft agl CHT to about 255, Coolant light goes on and oil temps around 240f or so. Leveled off and turned around again, cooled down on power-off approach. Did a couple of laps around the pattern, at around 700agl, it would heat up. I have been climbing out 75kts when I would like to be around 65kts. Straight and level flight at 90kts did not lower the temps
One person got out of the plane to lower weight, and tests repeated with similar issues. Performance is fine and can climb pretty much at book before beginning to overheat. I am sure temps would continue to rise if power wasn't cut and would rise much faster if climbed at Vx.
Fresh gas, Sport plus oil, sensors checked out, new plugs 30hrs ago, Radiators looks clean/fins straight, all cylinder heads approx same temperature when cowling removed. Engine runs and idles as other 912 I have flown.
Mechanic is not a Rotax expert and is out of ideas and there are no Rotax specialists at the field.
Thanks
