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November-2017
MauricioB's

"Cox Tee Dee .010"



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Seized overnight?!?

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Seized overnight?!?

Post  batjac on Fri Jun 03, 2016 4:17 pm

Last night I mounted three engines on my test stand so I could get to test running and tweaking them this afternoon.  The TeeDee .049 and the Medallion .049 ran fine.  But, the TeeDee .051 that I wanted to tweak is inexplicably seized.  I pulled the cylinder to make sure it was okay, but for some reason the crank is seized.  I don’t understand why.  It was flipping over easily last night before I went to bed.  I used the same light sewing machine oil on it that I always use on my engines, so I can’t see how that could be the problem.  I’ll have to tear it apart tonight or tomorrow and see what’s happened in there.

The Perplexed Mark
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Re: Seized overnight?!?

Post  pkrankow on Fri Jun 03, 2016 4:27 pm

FOD

something is in the intake is my first guess

Phil
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Re: Seized overnight?!?

Post  Ken Cook on Fri Jun 03, 2016 4:53 pm

If the carb body collet came loose it can jam against the back of the prop drive not allowing it to turn over. I've had this happen when the engine was running.
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Re: Seized overnight?!?

Post  TDbandit on Fri Jun 03, 2016 5:29 pm

Ken Cook wrote:            If the carb body collet came loose it can jam against the back of the prop drive not allowing it to turn over. I've had this happen when the engine was running.
Ken has a great point, I had that happen to me recently in fact sounded just like a seize. Another thing is if it was seized before and had varnish in the case sewing machine oil may loosen it up but it can re-harden and grab the crank again over night. try heating up the case and see if it will loosen, if it does reoil and bolt er up and run it. the heat and constant oil/fuel will help rid the case of most of the goo.
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Re: Seized overnight?!?

Post  batjac on Fri Jun 03, 2016 11:17 pm

Well, I took the thing apart. The collet was nice and tight, so that wasn't it. When I took it apart, the crank was free of any marks on the shaft, and there was no FOD in the case. When I wiped everything down and oiled it up, the crank slid in easily and turned smoothly. Until I seated it against the thrust bearing surface of the case. It seems that somehow the bearing surface appears to have become galled. I cannot understand how that happened. But, it did. So, I took some polishing compound and hand lapped the crank face to the bearing surface.

After cleaning it all up, oiling, and re-assembling the parts, it turns over freely again. Hopefully, tomorrow it will still turn over. We'll see.

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Re: Seized overnight?!?

Post  batjac on Sat Jun 04, 2016 10:07 pm

Well, it runs. But I'm only getting about 20K RPM on a 5x3 rubber ducky. I was expecting a couple thousand more. And it's sucking the fuel REAL fast. I'm only getting about 3 1/2 minutes on an ounce of fuel. I haven't any more time to play with it until next weekend, but I'll try a different needle valve and different heads.

What are Y'all using for shims under the Galbreath plugs? 5 shims to start?

Besides the rubber ducky, I tried a Cox 6x3 and got 14K. Still less than I hoped for. I searched my prop drawer and found some old Windsor plastic props. I had several 6x3.5 and 6x4 props. I tried a 6x3.5 and got 15K. Maybe I'll run with that for now, and see how the Master Airscrew and Tornado props Rusty is sending me do. Now I kinda wish I'd bought some wood props that I saw a few months ago at a swap meet to try also. Only one guy had any 6x3 wood props, but he wanted about 4 dollars each. More than I want to pay for props I'll most likely just break on landing in the grass.



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Re: Seized overnight?!?

Post  RknRusty on Sun Jun 05, 2016 9:03 am

Don't be disappointed, in my experience, all Cox soft props are slower than the other brands. It'll turn up with an MA. Besides 20k on the bench means probably 22 in the air. That's about what I expect from mine and my .051 has been average-clocked on a pitch pipe(on a Tube video) at 22.5 with an MA 5.5x3. In the past year, I have found Fritz/Glowplugboy 35% to be the hands down fastest, Cox Super Power(?%) next, and Sig 35 the unquestionable slowest with the TD .049 on my Li'l Satan.

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