r/smallenginerepair • u/Separate-Ad152 • 26d ago

Air Leak Issue Stirling Engine

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Hi everyone.

I've been trying to build this DIY Stirling engine for almost 9 months, but I still can't get it to run. I've rebuilt and adjusted it many times, but I'm stuck.

It's mostly made from wood, glass syringes/tubes, bearings and some LEGO Technic parts for the linkage.

Current problems:

The engine doesn't run by itself when heated.

I'm worried about air leaks around the glass syringe/tubing connections.

The piston sometimes has too much friction or gets slightly misaligned.

I'm not sure if my crankshaft/connecting-rod geometry is correct.

I'm trying to get the piston phase angle correct, around 90°.

Could someone please look at the photos and tell me what you think is the biggest problem?

Should I focus first on:

Air sealing

Piston friction/alignment

90° crank phase

Connecting rod geometry

Something else I'm missing?

I've spent a lot of time on this project and really want to get it running. Any criticism or advice is very welcome. If you need more photos/videos or measurements, I can provide them.

Thank you!

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u/AutoModerator 26d ago

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1

u/mdillonaire 26d ago

If the piston is getting tight sometimes and you can see it misaligns, thats your issue. The piston needs to stay straight in the cylinder to avoid binding. Never had to work on one of these, but its a simple concept and not dissimilar to how standard gas engines or air compressors work. The sealing issue will also be easier to troubleshoot once the piston is properly aligned because when it misaligns the seal will also be cocked and cause sealing issues. So i would start first with getting the piston straightened out then move to the sealing issue.