Rotax 582 Radiator Cap WOES

[JustPlaneMike]

The 1993 KitFox II with a Rotax 582 model 90 gray head I recently purchased and now working on the conditional inspection . The Radaitor Cap was the 6-8 PSi one that needed to be changed to the 13 psi one. Searching all forums I was lead to a cheap alternative which was a Motorbike Radiator Cap A Triumph part number T2108005 I found one and ordered it For around $25. Great. well when I got it it was to small. was the information wrong? So much time was wasted looking for it I decided to go ahead and and order the Rotax part number 922-072 from Leading Edge Airfoil. Well guess what it to was to small and the Triumph was an exact match.
Leading Edge suggested calling KitFox cause he thought they shipped out the caps with the kits and that it was proably a standared automotive Cap. I was able to supply the Listed part number from the build manual E-62- Kitfox did not have a match for the Cap- He did search and found some histroy that Denny AeroCraft, purchased the radiator caps from a local parts store.They did not use the cooling system from Rotax. no parts number available. Wonder how much other automotive parts were used? I going to return part to Leading edge unless someone want to buy it, I also have the Triumph clone cap for sale.
So before I go to the auto parts store and They ask what vehicke is it for? so they can lookit up on the computer cause they don't know how to find parts otherwise.
Does any one have an autopart number for the automotive cap I need ?
Ill try to add photos
Ist photo is the Triumph Cap any my old Cap 2nd photo Triumph part number 3 filler neck on plane 4 My cap and the Rotax Cap,
Thanks for any feedback and hope this helps some of us with the older kits

[109JB]

When I had to replace the cap on my 582 powered kitfox, I just took the old one to an auto parts store and told them I wanted a 13 psi cap. Guy walked in the back and came out with a 13 psi cap. Now this was a sort of old time auto parts store with an older guy who actually looked like he knew how to work on a car, not Autozone or O'Reillys where the workers are high school kids who think working on a car means putting bullet hole stickers on it, or installing the largest speaker known to man.

[mike92104]

The hex design looks like a Moroso cap. Maybe this one will work for you:

https://www.summitracing.com/parts/mor-63313?seid=srese1&gclid=Cj0KCQiA3smABhCjARIsAKtrg6KhexD5eyt4GiL4Nohz m3bs2Y5rAULJzodzfLahEYP-GuUmNqtwSt0aAjYCEALw_wcB

[Dave S]

JustPlaneMike,

Your photo of the original cap and and filler neck looks like what was the "standard" fitment for just about every car and tractor manufacturer of days gone by.

Trying to go make-year-model is hopeless in my opinion.

Should be plenty of caps out there if you can find a real auto parts store; and, I agree that Summit should have a cap which fits and is the right pressure rating - summit has about a huge variety of caps. I needed one for another application which required a "zero-cap" just a cap and no pressure spring - Summit had one.

[4Hummer]

Part number would sure be handy. I have the same Rad Cap on my Model IV with a Rotax 912 80HP. still haven't been able to find a match at the right PSI

[JustPlaneMike]

Now someone is saying in another form
The lower radiator pressure was for the early 582's with the non ceramic seal for the water/ rotary seal. Later (blue top) or modified greys are ok with higher pressure.""
I've got a gray head but I don't know if it's been modified or not so now I don't know if I should stay with the lower pressure or go with the higher pressure radiator cap

[109JB]

You want the 13 psi cap. The notion that a lower pressure cap is better for older engines because of the rotary valve seals is hogwash in my book. If it is leaking past those seals, whether they are ceramic or not, then you have to fix it, not cover it up with a lower psi cap than is called for. The current service manual says 13 psi to prevent water pump cavitation and it doesn't differentiate between gray or blue head.