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  #1  
Old 07-29-2009, 11:01 AM
fdmurphy44 fdmurphy44 is offline
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Default Gear Box Guru's??

As many have probably read, I am having a bit of an issue with our Fly C-Box. having disassembled it I noted that the 60 tooth gear is wobbling ever so slightly and once disassembled I found that the cone sleeve that mated the gear to the shaft is slightly worn as is its mating surface on the gear. It appears that the two did not engage fully ahd were only mated at the last 1/8 inch or so at the widest diameter of the mating surfaces.
Since this is all new to me and I could use some expert advice I thought I'd inquire and see if anyone was familiar with or knew someone who is. Any help would be greatly appreciated. The cost of a new gear set and split cone sleeve are EXTREME!!!! As is most everything else related to the motor.
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Old 07-29-2009, 02:08 PM
fdmurphy44 fdmurphy44 is offline
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Had a conversation with the fine folks at LEAF and it turns out that two of their mechanics (one being their gear box guru) are at Oshkosh. As luck would have we have one of our own and best 582 mechanics (and a damn good tug pilot) at Oshkosh. So, a quick call to Rick and WALLA..... He hunts them down at their LEAF booth and it turns out that Rotax changed the taper on the split sleeve and gear assemblies. Without knowing, the gear box had been modified for the correct ratio some time ago and the problem has now surfaced. We have a mismatched gear assembly/split sleeve (the gear set doesn't come with the sleeve) and so I have ordered the correct split sleeve and soon we should be back in business. At a very reasonable price I'd like to add..... If you can call anything to do with Rotax reasonably priced!!


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Originally Posted by fdmurphy44 View Post
As many have probably read, I am having a bit of an issue with our Fly C-Box. having disassembled it I noted that the 60 tooth gear is wobbling ever so slightly and once disassembled I found that the cone sleeve that mated the gear to the shaft is slightly worn as is its mating surface on the gear. It appears that the two did not engage fully ahd were only mated at the last 1/8 inch or so at the widest diameter of the mating surfaces.
Since this is all new to me and I could use some expert advice I thought I'd inquire and see if anyone was familiar with or knew someone who is. Any help would be greatly appreciated. The cost of a new gear set and split cone sleeve are EXTREME!!!! As is most everything else related to the motor.
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Old 07-29-2009, 02:49 PM
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Great work Frank (and Rick)
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Old 07-29-2009, 03:55 PM
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Frank,
Have you found out anything about the flaky temp readings???

What did you mean by the "weird" readings? Do they vary all over the place or are they high or low when the plug readings are looking good?

I'm concerned that the crank seals might be leaking which can cause very high EGTs and a fried engine.

Good job on the reduction drive!

Last edited by mjp103; 07-29-2009 at 03:57 PM.
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Old 07-29-2009, 07:03 PM
fdmurphy44 fdmurphy44 is offline
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Mike, been seeing the EGT's flip flop and ranging from the low 900's to the mid 1100's. Nothing is consistent and at times they both appear normal and in the 1050 range?? These temps are at full throttle during towing or me flying solo but still at full throttle and performance climb. Have checked the carb boots and replaced them due to some cracking. There appears not to be an issue with the seals as far as anything leaking out of them.
Matt Kollman is back in town and has agreed to go thru the wiring and connections on the EGT's. There is also a resistence/temperature relationship that can be checked with an ohm meter that has not been done yet. But while the engine is not running they are very close to the same value.
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Old 07-29-2009, 08:33 PM
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Frank, how do the plugs look?
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Old 07-30-2009, 07:36 AM
fdmurphy44 fdmurphy44 is offline
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They're about 3 inches long, with a threaded section about 1 inch long with an electro...... Comon..... You've seen plugs before!!!

Don't know Mike. I have not taken them out to look at them? The 25 hour mark is coming soon and thats usually when I take the first look at them. Gues I have become too used to and rely too much on the EIS. Always worked fine with the last engine. Thought it would be the same with this one. You know what is said about making assumptions!!
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Old 07-30-2009, 07:54 AM
mjp103
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Maybe it will just turn up to be a loose connection or slightly corroded probe wire connection or there's the possibility that it could be a problem with the EIS itself.

If someone has a spare analog EGT instrument, you could install that to see if the temps run consistent. I may have one, if I can find it, though I probably would not have a probe wire connection long enough to reach the front of the Fly.
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Old 07-30-2009, 10:32 AM
fdmurphy44 fdmurphy44 is offline
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Well, if you'd like to check to see what you have that could be helpful. Don't make it a high priority though, we will plug away at what we have eliminating probable possibilities. I'll keep you posted here.

Thanks
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Old 09-17-2009, 02:11 PM
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Default High EGT Problem

Frank,

Here is a reply from one of my Rotax guru friends specifically aimed at the egt problem.

As to the Rotax engine. The jetting should not need to be different from on carb to the other. If they require different jetting then there is a problem. Here are some steps to verify what the problem is.

1. The first thing I would do is swap the inputs to the gauge on the back of the gauge. If the high temp stays on the same side of the gauge after the swap them then then replace the gauge. If it moves to the other side then the gauge is good
2. Next swap the EGT probes by removing them and reinstalling them in each others port in the exhaust. If the temp moves with the probe then replace the probe. If it stays on the same side then you have an air leak in the engine on that cylinder somewhere.
3. Remove the plugs and check for damage to their gaskets and cracks in the CHT senders. If either are damaged it should be replaced.
4. You could also have a leaking spark plug Try changing them.

5. Check the carb boots for cracks or damage.

6. Next swap the carbs. If the problem moves with the carb then the carb needs cleaned thoroughly all jets and passages. Check the vent lines for blockage. Make sure the holes in the lines are open. Then check the float levels. This is done by turning the carb over in sighting the float arm. it should be level with the body.

7. check the torque on the cylinder heads and intakes.

8. The engine needs to be leak tested. this is done by removing the intakes and exhaust. The blocking them with plates and pressurizing the engine to 11 lbs with air watching the presure to see if it drops.


Regards,

Dan J.
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