Rotax 582 Radiator Cap Confution

[Turbo_Boss]

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.
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.

THX,

Isaac

[Duck Rogers]

Rotax suggests a 0.9 bar cap. If your radiators are interconnected then I would think, whether 3 radiators or 1, you still only have one whole water system and therefore a 0.9 cap is what I would fit.
I can't see the rationale behind suggesting a 1.2 bar cap.
If you have 3 radiators that are interconnected, with each radiator having a cap, then I would fit 2 with 1.2 bar caps and one with 0.9 cap.

Right know my water & engine temperature is OK.

Then leave everything as is. Don't scratch where it's not itching

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

The number should be stamped on the cap. Sometimes as a "9" for 0.9, or "11" for 1.1 and so on....

I have 2 radiators on mine, with only one filler cap and it's a 0.9. No problems. Flying at altitude here with temps in the summer up to 30deg C (88F)

[Morph]

the 1.2 bar pressure cap is recommended for 912 engines. By increasing pressure allows the water to run hotter before boiling. The 582 needs to run cooler rather than hotter.

Additionally if you are under high pressure you increase the risk of water being pushed past the seals of the rotary valve causing failure.

As Duck said stay with what you have. The pressure in the system will be equal to the weakest point. If you have one .9 cap and the other 2 are 1.2 then the pressure will be rugulated to .9bar before the .9 cap starts releasing excess pressure. This cap must be the one with the overflow pipe. The other 2 will never work.