Reasonably Priced Coolant System Cap

I know we would all like to think it is a specially made cap but there is just not the market or justification to go that route.

I have never replaced a cap on any of my vehicles, and you want to replace one on the plane.  

That "More Dependible" Theory isn't holding up very well.

All the connectors, sensors, and controlls are sourced from the Automotive world.

There is no reason that the pressure cap isn't also.

I have tried to fit tha cap to every car I could get my friends to allow me to.  No Luck.

If you can schmooze an Auto Parts Store Owner to let you look in the Boxes on his shelf, I am sure a cap made for a 1990's German Vehicle would be the match.

The problem is finding the match.

For the life of me, I do not understand why there are 137 different sizes!!!

It would seem like about 6 would cover evything from a Beetle to a Kenworth.

 Agreed Bill. 

I did have an engine that was not holding the correct amount of pressure in the cooling system and ended up allowing coolant to blowback under pressure into the overflow bottle and not only soaking the engine compartment but of course, splattering the windscreen.  By the time it was all said and done every time the aircraft was flown coolant had to be added.  Replacing the cap solved the problem.  

Another mechanic/friend suggested wandering through a salvage yard checking different foreign cars and if I found one that matched I would know what cap to buy at the local auto parts store.  

Cannot help much...but it loos like a motorcycle radiator cap to me perhaps BMW ??. Sometimes with similar questions I have used a magnifying glass and found a serial number or casting code and googled it to find the answer. Rotax also uses a lot of snowmobile parts in their engines...

Thanks Glenn,

Good idea.  I hadn't thought about some of the other vehicles that Rotax engines are used in.  

Glenn!!!

You hit the nail on the head or maybe the cap.  I started searching deeper and in different forums and low and behold a BMW 17112345074 radiator cap fits.  The parts can be found for about half the price and funny enough I got the information from an aviation-related forum, teamkitfox.com.