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Old 06-24-2021, 05:03 PM
Josh M is offline
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Originally Posted by Planebuilder View Post
That is a bearing that more than likely got hot at some point for sure or one that had a lot of run time on it. Iím assuming that bearing was replaced in the first go round. Only way to know for sure is to remove the hub and see whatís going on behind it. Also if you still think you may be running hot take a look at both pistons thru the exhaust ports. If ran hot for any length of time the piston skirts should be discolored . If theyíre clean and relatively bright I would tend to believe you just have a bearing or seal problem . Out of balance propellers can really wreak havoc on that front bearing as well. Again hope this helps in some way.

Scott
I'm 95% sure I'm not running hot. Little to no markings on sideskirts, and relatively clean. Tops of pistons also relatively clean, except for like 1 or 2 peas sized areas of carbon (this was on the cylinder that had the collapsed gap, left cylinder).
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Old 06-24-2021, 05:19 PM
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Lots of good advice here. Unless tearing it down and doing the work yourself is an option I have to agree with the previous poster. Pull the motor and send it in for repair. Bearings are pretty cheap and really not worth pushing them past their service life. Let us know how it turns out.

Scott
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Old 06-24-2021, 06:52 PM
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If not heat ,it could be just a bad bearing .
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Old 06-24-2021, 07:08 PM
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Originally Posted by closetguy View Post
If not heat ,it could be just a bad bearing .
The seals on many of the bearings used in RC engines are not the greatest from day one and they really don't hold much pressure even when new. DA or Chinese, they all go bad in time. Even if the rear bearing (second from the front in a twin) seals fail, that bearing will probably live a normal life as it will get adequate lubrication from the fuel / oil. The front bearing depends mostly on the grease put it at the factory but it will get a fair amount of lube after the rear bearing seals fail. At some point in time though, the engine will start running like crap and you will know it is time for service. I'm sure a hot (didn't say overheated) engine will accelerate the seal degradation process. I'm thinking this is the case with the engine being discussed here. I'm thinking this engine is being pushed to the limits but that's why we buy them and what we expect from them.
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Old 06-30-2021, 07:44 AM
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a faulty crankshaft damages the bearing seals (oil from the front bearing) - - - insufficient tightness - - - excess air leads to depletion of the fuel mixture - - - engine overheating
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Old 06-30-2021, 09:02 AM
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Louvers

Perhaps you should consider adding some louvers to the sides. I added these and my temps dropped from 325+ down to 250-275. Maybe run it a little richer. I have a temp sensor on mine. I have 2 DA 70ís both have louvers on the cowls and both run low temps. I run them hard all the time no issues. Good luck!
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