Learnin' Stirlin' - a peculiar looking Stirling Engine

[Dave Otto]

I just finished up the alcohol burners for a couple 1/2 size Lake Breeze fans I'm working on, pretty pleased with how they turned out for a first time go at it.

Dave

[Sanjay F]

Wow, Dave you should be pleased they look incredible; so many skilled people here, with skills I've never even heard of! 

[Dave Otto]

Thanks Sanjay! 

[Charles Lamont]

Another interesting restoration job that seems to be coming on nicely. May I suggest the performance could be improved by fitting some insulation material between the brass flange and the lower steel parts. Something like thick gasket material. This should reduce the amount of heat getting to the water jacket. 

[Sanjay F]

Sounds like a good idea, I have some thick gasket material, let me take a look

[Sanjay F]

Made a bit more progress today, smoothed off the JB Weld repair on the displacer piston, repaired the top connection to the radiator, started reassembly of the bottom half of the engine sealing as I go. My goodness that blue stuff gets everywhere!

I made a thick gasket as suggested. I had one piece of the thick stuff left which was just enough to fit, my gasket punches were having trouble getting through it I think they may be worn

[Sanjay F]

Here is the 1st run of engine......woo hoo................. and all was good until I noticed the wetness around the displacer rod again and the engine getting slower and slower! 

https://www.youtube.com/shorts/cn3mU1BAiW0

I figured there must be a leak between the water jacket and the displacement cylinder so I dismantled everything and did what I should have done before assembly which was to fill the jacket full of water and watch for leaks ..........I thought I might see a drip here and there, but watch the video below .............it's a torrent!

<a href="https://www.youtube.com/watch?v=F8rkDdD55Ik" target="_blank">http://www.youtube.com/watch?v=F8rkDdD55Ik</a>

On further inspection, I have found the cause of the leak 'there's an 'ole yer pipe, guv!' 

Take a look at the picture below where I've circled it, you'll be able to see it. So I mistakenly blamed myself for the water filled displacer whereas it was this hole all along; the only way I can see of repairing it is letting the entire thing dry out in the 'warm' weather and then getting a bit of JB Weld in there and then gently smoothing it out?

Given the engine runs even when water-logged I'm holding out hope that this engine will be runner ......... at some point! 

[Dave Otto]

Congrats on getting it to run!
If that is the bushing that the displacer rod runs through, you might be able to bore it out and loctite a new bronze bushing in place. don't remove the entire bushing, just maybe half of the diameter.

Dave

[Sanjay F]

Firstly I'm glad I found the problem, I'm not good with mysteries!

I think I'll see how the JB Weld goes and it that doesn't pan out I'll take it from there and look at boring it out. I think I'd have to drill it out and ream it as there's no way I can see to get it mounted in a chuck for the lathe as the jacket has been soldered on good and proper!

[Sanjay F]

The JB Weld didn't work, the wall of the bush is too thin for it to take and when I sand it just drops out 

I will partially drill out the bush and see if I can loctite a new piece of round in there but I have a feeling I'll take out the entirety of the bush wall and leave just the 2 end wider sections onto which I can loctite the new bush?

I have sketched what I think the bush cross section looks like, I could well be wrong and the section with the hole in it could be just a single thin section of the bush? 

[Jasonb]

Or it could just be parallel and years of water sitting in the jacket have rusted it away which is why you now have an ever increasing hole.

[Sanjay F]

Yeah true - guess, there's only one way to find out ................... 

[Sanjay F]

I managed to get the cylinder mounted in the 4-jaw and I'm gingerly drilling 1 letter size bigger each time. The original bore was 5/16" (0.313") and I have just put a 0.348" drill through.

I have approx. 1/16" wall thickness left so don't know how much I should leave/carry on drilling (next size up is 0.366"), but you can clearly see the internal hole has got larger so it must've been parallel and just rusted away

The bush is made of mild steel and so should a new one be made of the same material?

[Dave Otto]

Is you plan to leave some of the original bushing and install a thin sleeve?
I would make it from bearing bronze.

Dave

[Sanjay F]

Do I make the sleeve first and then install it or do I plug the hole with the bronze and then drill and ream it to diameter? Not sure how to do the first way as I would have thought the sleeve would be too thin in the chuck and collapse in on itself?

Either way I'm just not sure how much of the original bush to leave, I only have approx. a 1/16" wall diameter