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  • Re: 582 high engine temp

    by » 12 years ago


    I can now answer question one at least... the thermostat is in fact behind the small water connection on the other side. Thanks google images

  • Re: 582 high engine temp

    by » 12 years ago


    Mike,

    Your pump is turning in the right direction. It pulls the coolant from the hose into the center of the impeller and forces it outward and into into the block through the two holes on each side of the impeller. The small hole in the impeller is to allow cavitation bubbles to escape.

    The thermostat is normally located right where you found it. If you have to replace the thermostat, be sure you get the one for the model 90 greyhead. The model 99 bluehead thermostat is designed entirely differently.

    Depending on how your cooling system is mounted, it is sometimes difficult to drain all the fluid out. Especially in the crossover hose under the twin radiators. Not likely to be any air in there though. One thing you might check is the steam vent with the small hose attached which goes from the cylinder head to the radiator. ( I can't remember if the greyhead has one or not) If this is blocked, it can allow air and steam to be trapped in the top of the head right where you need coolant the most.

    Bill.

    Thank you said by: Michael Regan

  • Re: 582 high engine temp

    by » 12 years ago


    Well thats a relief... thanks Bill. Now I can discount the pump altogether at least.

    Today I pulled out the thermostat and put it into 65 degree hot water and it opened just nicely, so I can also discount the thermostat. Next flushed the engine with plain water, and refilled it with plain water as well. No mater how slow I poured the water, and no matter how high or low I put the tail (to get level), I could not get more than 2-1/2 liters of water into the engine. I then ran it at 4000 rpm for 5 minutes to try and clear any air locks so I could get the 4 liters the specs say, and she reached 170-5 degrees, but the main thing to note is the air lock did not clear and the water level stayed the same.

    Back to the drawing board. Waited for the engine to cool down, then disconnected the radiator hose and hooked up the garden hose and flushed the whole engine both ways and noticed no discolor in the water at all. It all looks good, so put it all back together but before I put the thermostat back I drilled a couple of 1/8" holes in it to hopefully help the coolant seep through better so I might refill the full 4 liters this time. Its too dark now to do anymore now so will finish tomorrow and test fly and see what happens.

    I didn't see and steam vent from the head, but did see what might be the steam vent coming off the top of the water pump and going back to the radiator cap. See the pic below and some others as well just to give you an idea of my setup.

    Mike
    Cooling.JPG (You do not have access to download this file.)
    Overflow.JPG (You do not have access to download this file.)
    RadiatorCap.JPG (You do not have access to download this file.)
    Thermostat.JPG (You do not have access to download this file.)
    TwinRadiator.JPG (You do not have access to download this file.)
    WaterPump.JPG (You do not have access to download this file.)

  • Re: 582 high engine temp

    by » 12 years ago


    Mike,

    Didn't realize the engine was inverted. For an inverted engine, the water pump is the proper location for the steam vent. It sounds like you have checked everything. Could it be that your temp gauge or probe is reading wrong? Easiest way to check is to remove the probe from the block, leave it hooked to the sending wire and attach a temporary grounding wire to the probe. Now dip the wet end of the probe into a cup of very hot water with a thermometer and see if the gauge and thermometer match.

    You might get lucky and find you don't even have an overheating problem.

    Bill.

    Thank you said by: Michael Regan

  • Re: 582 high engine temp

    by » 12 years ago


    You mean all Avid mk4's dont have them inverted? Hahaha...shows how much I know. In that case, why would any sane builder invert the darn thing?

    Bill, will try that idea of yours when I get back from todays test flight when I get her all back together again. Thanks for the hot tip mate :)

    mike

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