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Oil temps high, are Oil Coolers required?

in 912 / 914 Technical Questions 6 years ago

  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    Keep the rpms above 5200 in level cruise. Low rpms and lugging the engine will generate more heat. Descending, at 4500 or lower rpms should decrease your temps.
    A small oil cooler will make a big difference from no oil cooler.
    Have some aluminum tape on hand , you will need it at some point.
      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    So update on my heating issue. Installed a small 7 fin Earl's cooler and the temps made a big difference in certain spots. Below are my numbers.

    45 psi oil pressure
    Cyldiner Head Temp 250 F (Max back) my sensors are not in the coolant but in the heads. Old 94 engine
    Cyclinderr head temp 200 F (Max front)
    Oil out the sump 220-240 F
    Oil into the pump 180-200 F
    Running it at 5100 on cruise
    Seeing about 90mph (did not give it a fair cruise test) Kitfox Model 4 Speedster

    My main big question is which oil temp do I care about? I have two sensors 1 going into the bottom sump of the engine and the other going into the front of the engine right next to the oil filter. When rotax states normal operating temperatures are 190-230 do I care about what goes into the front pump/engine or what is comming out the bottom sump?
      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    This has been debated numerous times.
    Logic would appear to favor worrying about the Hot Oil coming out of the engine, however...
    Rotax has historically measured and specified the Oil temperature going into the Oil Pump, essentially the Coolest Oil.
    So when they say keep it below 230, they mean the Oil at the Oil Pump.

    It doesn't have to make sense, it just what we do.

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

      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    Bill that's exactly what I was thinking. But it seems then if that's what I am being told my engine is running right on the money. Are there any normal operating temps for the Cylinder heads? All I find is the water temps from the manual and I don't get those temp #'s.
      
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  • Re: Oil temps high, are Oil Coolers required?

    by » 6 years ago

    From the Operators Manual.

    https://www.rotax-owner.com/en/support-topmenu/engine-manuals#912-series-engines

    Section 2.1 Operating Limits (912UL)
    Page 2.3 Conventional Coolant.

    Coolant Exit Temperature: Max. 120°C (248°F) ... Not Reported.
    Cylinder Head Temperature: Max. 150°C (300°F) ... You report @250°F, Good!
    Normal Cylinder Head Temps are not specified.

    Oil Temperature: Max. 140°C (248°F)
    Normal 90-110°C (190-230°F) ... You report 200°F, Good!

    It looks like you are running a little cool of average.
    Probably typical for an Autumn day in Oregon.
    You should be OK for next Summer.

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

      
    Report
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