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Rotax 582 Radiator Cap Confution


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Hello guys,


I have a Rotax 582 with 3 radiators. two are side by side the engine and the the other is under the engine.


I need to replace the radiator cap and checking on the CPS catalog it shows


Part No. 922-075 Cap with Gasket 0.9 Bar


My question is: Since I am using 3 radiators, Do I need a radiator cap with more bar?


Were I order Rotax parts, they recomend me to use the 922-070 Cap with gasket 1.2 Bar


I am a little confuse about this and dont know what to order.051_crying.gif.fe5d15edcc60afab3cc76b2638e7acf3.gif


I fly here in Central America and here is very hot with almost 100% humidity.


Right know my water & engine temperature is OK. I am changing the cap as regular maitenance. I really dont know if installing the 1.2 bar will have some negative efect.


In fact, I dont know what bar is the one I have right now


Please advise me what to order.







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G'day Issac -


As it's working fine - I would replace the cap with one of the same pressure, don't throw the old one away because if the new one changes things, you can go back to what you had and investigate further.


If you're not sure about the current cap you may be able to have it tested to fnd out the actual pressure.





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Cap pressure.


T.B. You don't need more pressure because you have more radiators, and the LOWEST pressure cap will be the one that regulates the system.


The maximum temperature that you can operate at without losing fluid is affected by the pressure, as the boiling point of any fluid goes up with an increase of pressure.


......Conversely, when you are up on a high mountain or in an unpressurised aircraft you can't open a thermos of tea without it boiling all over you. It doesn't get any hotter, it just boils at a lower temp. Nev..



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  • 4 months later...

0.9 Bar is what Rotax recommend for the 582.


If you increase the cap blow off pressure then the oil (water) seal behind the water pump wears out prematurely.



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