Low oil temperature post operation of about 02 hours

Brian,

  I think the replies from Garrett and Bill say it best.

1) There is no pressure in the return tank it is vented to atmosphere and any water vapor can easily exit.

2) As long as you do not have creamy soup under your oil cap it is getting hot enough.

3) Thermostats help with warm up  not peak temp...the ones I have seen are all around 70-85 deg opening

4) Tape seems silly but it works very well.

Bill Hertzel wrote:

On an aircraft with an Oil Cooler and No Thermostat, The oil passes through the oil cooler and the amount of cooling is determined by the Ambient Air temperature, The size of the cooler, and the amount of airflow.

More flow, larger cooler, and lower temp produce more cooling. (Lower Temps)

The easiest way to produce LESS Cooling (Higher Temps) is to reduce the virtual Cooler size by blocking the airflow to the cooler.

The Taping of half of the cooler is equal to replacing the cooler with one half the size, only a lot easier, quicker, and cheaper.

The more expensive options for less cooling are to reduce the airflow with mechanical air flaps or reduce the cooling oil flow with an oil bypass thermostat.

The bypass thermostat might bypass the cooler until 190°F is reached allowing the engine to heat up quickly, but after that, the temperature control reverts to the same conditions that exist if you had no thermostat.

The thermostat controls the heating of the Oil UP to 190° and Not the Cooling DOWN to 190°. 

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The oil in the Oil Tank is openly Vented to the atmosphere and then vacuum sucked back into the Oil pump.

There is no appreciable "Pressure" in the Oil System other than within the limited confines of the Oil galleries of the engine.

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You will not find any "Real Rotax Engineers" on this site.

This is an Owners/Users group composed of a bunch of very intelligent and experienced individuals, none of whom are employed or vetted by BRP/Rotax corporate.

We may not speak the official policy of the corporation but that doesn't mean we don't know what we are doing.

Having said that, and in all seriousness, you are well-advised to form your own opinion as to whether the information presented here is accurate or just a bunch of exhaust smoke!

 

 

 

 

Bill Hertzel wrote:

The bypass thermostat might bypass the cooler until 190°F is reached allowing the engine to heat up quickly, but after that, the temperature control reverts to the same conditions that exist if you had no thermostat.

Bill, the thermostasis oil temperature regulator will hold 190 deg F oil temp on a cold day during a long decent and or reduced power. It does not revert same conditions if you had no thermostat. Here is a quote from Thermostasis overview page on Aircraft Spruce website.

"Stage 2

As the oil reaches the desired operating temperature the internal bypass partially closes, automatically regulating and controlling flow through both the internal bypass AND the external oil cooler so that desired operating temperature is maintained."

I totally agree!

If the oil starts to cool below the thermostat temperature, it will once again revert to control the HEATING-UP of the Oil.

My point was that once above the Set Point the Thermostat does nothing to control the COOLING-DOWN of the oil and that "Cooling" is a function of the Cooler size and the airflow.

The phrase. "...but after that..." might better have been worded as "but above that temperature" so as not to have been misunderstood as "but after that time"  with the assumption that the temperature would continue to increase.

Thank you for pointing out the vagueness of my statement.

If the intent is to get the Oil above 100°C, a thermostat is not the answer.  This is where the Tape comes into play. 

Thermostat elements are readily available up to 90°C (195°F).

If you could even find one rated over 100°C, it certainly would Not be recommended for use.

After 5 years of messing with aluminum tape on my oil cooler (worked well) I came up with a simple but much more convenient way to block off part of the cooler without resorting to complex louvers/shutters etc. I can reach thru the air inlet to remove or add strips without removing the cowl. The aluminum is very thin, about 0.012" or so.

From the OM:

"Avoid operation below normal operation oil temperature (90 to 110 °C / 194 to 230 °F), as possible formation of condensation water in the lubrication system badly influences the oil quality. To evaporate possibly accumulated condensation water, at least once a day 100 °C (212 °F) oil temperature must be reached."

Really?  Every darn day you have to run your engine to 100 °C?  That what I would call "very optimistic" for most of us.  But aside from that, where is all this condensation water supposed to be coming from?  I thought the only place that the lubrication system was exposed to the atmosphere was at the oil tank.