Rotax 503UL engine pressure testing

Pressure and vacuum testing of the short block engine is one step of many quality control checks performed during my engine assembly process. No pressure or vacuum leakage is acceptable, if there is a leak, now is the time to find and correct it.

[@aerocam2]

I really appreciate you taking the time to capture, edit, narrate, and share your videos. I know it must be time consuming but it is so helpful to us flyers, not to mention how much safer it makes us when we’re flying our machines. A sincere thank you..!

[@RotacRepair]

Thank you so much for your kind comment. Yes the videos are time consuming however passing along knowledge to increase our aviation safety and enjoyment is worth every second. Happy flying!

[@aviation1036]

I’m Octavio from Calgary !!! I really like your videos and is always nice to talk to you on the phone ..

[@RotacRepair]

Always a pleasure to speak with you. Unfortunately I completely forget to call your Challenger friend back, could you please have him call me again.

[@clearprop]

Thanks, John. Still learning all the time. 🙂 👍

[@RotacRepair]

Your very welcome!

[@challenger2ultralightadventure]

Another excellent video. Cheers from Winnipeg.

[@RotacRepair]

Thank you for the kind comment! Happy flying

[@KirillNeduzhiy]

Thanks for the video, John! A very important procedure for these engines and their longevity to either find out if there is a leak in an operating engine or check if everything is alright after overhauling them. I have built a similar setup as yours some time ago, works great! Cheers from Germany!

[@RotacRepair]

Absolutely a good diagnostic tool as well, thanks for the positive comment

[@williamwhitley1174]

Thanks for another great video!

[@RotacRepair]

Glad you enjoyed it!

[@donsipes]

I'm confused. You used the vacuum port on one cylinder to test both cylinders. Isn't there a crankcase seal between the 2 cylinders? How does pressure get to the opposite cylinder?

[@RotacRepair]

An excellent question that needs a follow up video. I’ll have begun the supplemental video but haven’t completed all the clips yet.

[@MrHanowski]

Excellent! Is there a single crank position that's acceptable for testing? I don't understand why you have to move the pistons to different positions.

[@JohnBaker-og4zp]

Excellent question. Hopefully I’m able to clear this up for you. When the piston is at the very bottom position in the cylinder, the transfer ports are open directly into the crankcase and the upper cylinder area is exposed to the crankcase test pressure and volume. This allows for a direct passage of the pressure and flow volume from the crankcase to easily enter the cylinder area above the piston top. This method allows for any gasket above the piston top to be confidently tested for possible leakage. Please consider the opposite position with the piston at the top position. The only way for pressure to reach the head gasket would be the minuscule amount of pressure and flow passing by the piston rings. Eventually the area would pressurize above the piston, however the small volume of flow could potentially hide a seeping head gasket.

[@marksaxon6577]

John what sealer do you use / recommend when assembling the case halves.

[@RotacRepair]

The 503 crankcase sealer video will be posted shortly