912s running too cool in Foxbat

[jamespearce]

I have become the owner of an Aeroprakt A22L Foxbat built in 2010. The airframe and engine have just 60 hours. Despite the oil cooler circuit having a thermostatic control fitted, the oil (and water) temperatures go no higher than 70 degrees C at 4400 rpm in the cruise on a slightly cooler than ISA day. I know this is far from optimum for good engine protection and wonder which method(s) to employ to increase the engine and oil temperatures. ps. This is the Foxbat version with (probably unhelpful) gills in the engine cowling. Thanks, James.

[Nick Allen]

Are the thermostats working? (Eliminate the obvious ) And are the gauges/senders OK? (If perchance the temps were actually OK, but the readings wrong, then you might regret trying the raise the temperatures...)

[jamespearce]

Thanks Nick, good advice but as far as the senders are concerned both CHTemp outputs and the oil temperature are consistent with each other and the odds on all three failing are probably quite long. The cabin heating is via a gate in a 60mm flexible pipe attached to a duct fitted behind the radiator and I get very little heat coming into the cabin which suggests the radiator is not getting hot. A stuck open thermostat could be responsible for allowing too high a coolant flow through the radiator I suppose and needs checking as you say.

[Joseph Cullen]

I have a 912ULS running in my ARV Super2. The oil cooler and water radiator are in a scoop half way down the fuselage and the nacelle itself is well ventilated so it's all as well cooled as it could be. Oil and water temperatures, without an oil line thermostat, are around 100 C. I doubt very much whether excess air around the vents could be bringing your temperatures down as far as 70. I would suggest trying a separate measurement of either or both air and water temperatures immediately after you have landed; just be careful of the pressure as you open the header tank! If the engine is otherwise performing as it should, the most likely explanation is the gauging.