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Why drain antifreeze?

in General Tech Discussion 9 years ago
I have a 582 blue head. The Rotax manual says to drain the antifreeze if the engine sits from 4 weeks to 1 year "to prevent freezing". Since the purpose of having the antifreeze is to prevent freezing, I don't understand the reasoning.

I have 10 hours on new antifreeze and it seems a waste to drain that out for winter storage.

Anyone understand this?

Thanks,
Mike

  • Re: Why drain antifreeze?

    by » 9 years ago

    I would say that ROTAX is erring on the side of caution there.

    Your coolant doesn't lose it's "anti-freeze" properties over time (unless it's been regularly boiling off and you have been topping it up with straight water too much!) - but the anti-corrosion additives do steadily degrade with time.

    ROTAX cannot vouch for the 'quality' of your coolant before you put it into storage, so they recommend that you drain it. (No coolant, nothing to harm the innards).

    If you are certain that your 'new' coolant is still at the proper anti-freeze/coolant mixture for your local environment, and that it is indeed new enough that its anti-corrosion additives are intact (the various glycols can become extremely corrosive if untreated) - then you can make that judgement call. But "don't say they didn't warn ya!"... ;)
      
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  • Re: Why drain antifreeze?

    by » 9 years ago

    Hi Mike,

    Some of this depends on where the plane is kept and stored. If you change it out every two years you should be fine. They recommend things like this because everything is not created equal around the world. They are erroring on the safe side. Most 912 & 914 owners I know do every 2 years (okay) and I have seen some 5 years (I wouldn't recommend that type of thinking). We are only talking about 2/3 +/- gal.

    Same with spark plugs. These are too cheap to try and make them last until you turn 90 years old.

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

      
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  • Re: Why drain antifreeze?

    by » 9 years ago

    Hi Roger,

    Regarding your post above, reference to changing coolant in the 912 series of engines every 2 years and definitely before 5 years, I assume that you are referring to water+gycol cooling systems only.

    Could you please confirm my understanding that engine coolant systems using Evans NPG waterless coolant, that this change period does not apply? My understanding is that Evans does not needing changing until the TBO is reached. Is this correct?

    Regards
    Ian
      
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  • Re: Why drain antifreeze?

    by » 9 years ago

    I agree that water infused coolant should be changed out more frequently, but I still wouldn't leave Evans in till TBO. That's 1500-2000 hrs and for some 15-20 years. For 3/4 of a gallon in expense it's better to be more prudent in preventative care. Sometimes things sound good on paper, but don't work so well in real life situations.

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

      
    Report

  • Re: Why drain antifreeze?

    by » 9 years ago

    Thanks for the reply, gentlemen. I'm going to leave it in this winter and check it next spring. If all looks good I'll consider going to a 2 year replacement cycle.
      
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