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OK, some issues here I'm hoping you can help me solve

I have a brand new Rotax 582 on my T500 Thruster, the engine has just turned over 25 hours on the clock. It is driving a 68" 3 blade Brolga prop with 12 degree pitch blocks through a "B" reduction box at 2.58. Now this engine has always tended to overheat from run-in on. I have a hard time keeping the temps below 80 degrees indicated on a brand new VDO gauge connected to a brand new sensor in the engine head, all connected together with the wiring that came with the unit. So, unless the new gauge is faulty, I think the temp gauge is reading correct. I will, however, double check this next time I'm at the airfield by sitting the sensor in a pot of water and heat it up. I'll cross reference the temp gauge reading with a thermometer. I have only just pulled the prop[ apart to check the pitch, and I must say I was surprised to see such a fine pitch. I was expecting something near the high side of the range, around 16 degrees. I thought the overheating would be caused by too coarse a pitch setting and I could reduce the over temp reading by reducing the pitch - but not so. Another complication for you to digest; I have never been able to get full (6800) revs from the 582, either on the ground or when flying around. Most I've got is 6200RPM, so again I thought this would be due to a coarse pitch setting. Now I have to rethink. The EGT readings are identical at about 1100 on the gauge when at 6000RPM, so I reckon the carbies are right. I checked the barrel slides in the carbies and they are opening right up at full throttle.

So I have 2 issues - an overheating engine, and an engine that is not achieving full revs.

Where do I go from here learned forumites?

Pud
  • Re: 582 Blue head overheating problem

    by » 9 years ago


    Ian,

    Could be the pitch and the mixture. Too coarse a pitch and and it causes both low RPMs and sometimes,but not always, overheating. 1100f EGT sounds a little high for 6000 rpm. You might try reducing the pitch to achieve the full RPM and also raise the jet needle one notch to richen the midrange mix and cool things off. Raising the jet needle will not affect the WOT temps.

    12 degrees is really not too fine for a three blade prop that big. That is about the pitch I was using on my 64" Powerfin, so I'm guessing you could go finer with no problems with a 68" prop.

    Bill.

  • Re: 582 Blue head overheating problem

    by » 9 years ago


    Hi Ian,

    This sounds like a fuel delivery issue (my first guess) or a possible air leak.

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


  • Re: 582 Blue head overheating problem

    by » 9 years ago


    Thanks for the reply Bill,
    Looking at the Ultra Prop documentation for the Brolga props, it says for a 582 engine to use (for a 68" prop) between 12* and 16*. Given these parameters I was very surprised that the pitch blocks I have are at the lower end of the scale. I was thinking the egts were within the normal range according to Rotax documentation. I will be changing the spark plugs this weekend so will inspect them as well for an indication of fuel mixture. Roger has suggested a fuel delivery issue so I'll do a bit of investigating there as well, although with my investigations already I think this is a low probability item. I'll check anyway. Will also check the rubber carby flanges (only 25 hours old)to see if any air leaks there.

    Pud

  • Re: 582 Blue head overheating problem

    by » 9 years ago


    Ian,

    One thing you might also check would be the thermostat. It won't help the RPMs or EGTs, but it could be part of the cylinder head heat problem.

    Bill.

  • Re: 582 Blue head overheating problem

    by » 9 years ago


    How do you check a thermostat Bill? It was new (came with the brand new engine obviously) 25 hours ago.

    Pud

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