low oil temp readings

by Roger Swanson in General Tech Discussion 7 years ago

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Re: low oil temp readings

by Roger Lee » 7 years ago

Roger Lee

125 5.12k 4.53k

Okay Rob and Michael time to chime in. :)

Hi Bill,

You're correct about heat loss from the tank and the entire exposed engine, but the temp is measured at the oil pump and even if his is cooler than many of ours in a cowled engine it is still cooler through the engine because it started off cooler..

As an example if ours is 210F as it starts through the engine it will be hotter by the time it exits. If his is only 145F going in then it will be cooler at exit and in the tank.

Rotax doesn't measure or set their temp specs from the bottom of the engine or I think they would have put the probe there and not at the oil pump. When we warm up we use the oil pump temp probe location for the 120F operating minimum temp.

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

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Re: low oil temp readings

by Roger Swanson » 7 years ago

Roger Swanson

1 3 0

Never thought about the cooling effect of the oil tank. Would it make sense to wrap the exterior of the oil tank with some kind of insulation material? If so, what would be best and how would it best be applied securely?

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Re: low oil temp readings

by Roger Swanson » 7 years ago

Roger Swanson

1 3 0

Here is a video of a product called "Armacell" being attached to a tank. Would this be a solution?

http://corporate.armacell.com/en/press-room/videos/armaflex-sheet-small-tanks/

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Re: low oil temp readings

by Bill Hertzel » 7 years ago

Bill Hertzel

13 1.95k 7.96k

Rotax doesn't measure or set their temp specs from the bottom of the engine or I think they would have put the probe there and not at the oil pump. When we warm up we use the oil pump temp probe location for the 120F operating minimum temp.

Apparently, Rotax re-thought the position of the Sensors when they designed the 912iS engine.
The Oil Temp and Pressure Sensors are now at the rear of the engine under the starter.
About as far away from the Oil Pump Intake as you can get.

Measuring the temperature of the oil at the intake of the pump makes as much sense as measuring engine water temperature as it leaves the radiator.
You want to know how hot the engine is running, not how cool the oil or water radiators are.

The 912iS and ULS engines both specify the same 120F Oil Temps before powering up despite the extreme differing sensor locations.
This at least poses some questions.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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Re: low oil temp readings

by Roger Lee » 7 years ago

Roger Lee

125 5.12k 4.53k

Hi Bill,

Merry Christmas.

I do agree on the placement of the oil temp sender, but that's what everyone has to work with and what Rotax used for its temp ratings.

The 912iS has it's oil temp probe in a different place because the entire back end is in an oil bath where the 912UL series isn't. Temps, especially high temps in the stator area would be far more important. I think sitting on the ground at warm up for a 120F temp has to be close enough for operational use. There just isn't enough air flow to cause a difference like in flight.

I haven't done this, but would be interesting. Take oil temp readings in the tank at the exact time they are taken at the oil pump probe in flight. Then also compare these readings from a cowled engine with an open air engine like the aircam in the oil tank.

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

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