High oil temp rotax 912 100hp

by ken holloway in 912 / 914 Technical Questions 12 years ago

Just purchased a 2009 Bushcaddy with 912ul 4 stroke 100hp engine. Using 10W40 oil and oil temp running 260F plus while engine under strain and operating around 250F normal... tried plane twice in 20-24C weather and now parked until I can find out why oil temp so high. CHT, oil press both fine... any suggestions on where to start?

Re: High oil temp rotax 912 100hp

by Roger Lee » 12 years ago

Roger Lee

131 5.38k 5.44k

Hi Ken,

A few things to consider,

Prop pitch too course. If it is a ground adjustable shoot for around 5600 - 5650 WOT at your average cruise altitude. Unloading the prop can get some significant temp reductions. That should give you a pretty fair balance of flight characteristics. Plug gaps this time of year .027.. Kinking or reduced radius in coolant and or oil hoses. Poor air flow through the cowl. Carb needle clips should be at the #3 position. Maybe someone had moved them and its running too lean. Do a carb sync. Check the radiator for the oil and coolant for debris, they may need to be flushed out through the fins if filled with dirt and oil. If you are using Evens coolant get rid of it and use a 50-50 mix. Evens carries a 20-30F temp penalty. These are a few of the common causes.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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