Rotary Engine Failure Discussion Discussion Of causes, diagnosis and prevention of engine failures

Bearing failure!

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Old 04-11-2008, 11:25 AM
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hello!



I'm stuck on this one, haqve anyone seen this before? the rest of my bearings looks OK, but the front stationary bearing is really f***!



this is a newbuild engine, with 1new rotor any 1 new housing. the rest is the same as i have been running og for 30 000km.



i found some metallic particles in my oil after 200km, and tore the engine apart, and found this. NO damage to the rotors or housings.



have flushed the oilpassages, and found nothing.. would be great to find the reason...



any ideas??



Thanks,stig
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Old 04-11-2008, 01:44 PM
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my buddies had a couple FD motors do that. i think in both cases the engine was rebuilt, and the bearing was reused when it really shouldnt have been
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Old 04-11-2008, 02:54 PM
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Ive had that happen twice on brand new bearings. First time the thermopellet failed in the cold position, thereby dumping oil pressure that should have been going to the front stat gear. Second was I removed the OMP drive gear and failed to plug the oil feed for it, with the same result. Both bearing failures happened at high rpm after the engine was broken in.
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Old 04-12-2008, 06:13 AM
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thanks for replies!



i used the thermopellet on this engine, but when i'm rebuilding it over the weekend I'æll just put in a replacement.



so, when you forgot the oilfeed for the OMP, where did you forgot to block? i removed the OMP last year, but did'nt remove the gear inside the front cover before this build, can i have messed things up there?
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Old 04-12-2008, 10:39 AM
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Theres a small hole in the iron and front cover in the front cover flange near the CAS. Thats the oil feed for the OMP. If I have the engine apart, I tap the iron and put a set screw in. If the engine is already together, I do it to the front cover.
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Old 04-14-2008, 07:32 AM
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Originally Posted by mazdaspeed7' post='898488' date='Apr 12 2008, 05:39 PM
Theres a small hole in the iron and front cover in the front cover flange near the CAS. Thats the oil feed for the OMP. If I have the engine apart, I tap the iron and put a set screw in. If the engine is already together, I do it to the front cover.
okei, i guess u are thinking of this hole?



i have taped it, and blocked it with a setscrew.



is really that little hole enough to reduse the pressure to the bearing so it fails?



thanks for the info, had not found that by my self!!
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Old 04-22-2008, 08:37 AM
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Thats the one, and yes, its enough to kill a bearing under the right circumstances. But given that its already blocked off, Id be looking elsewhere for the problem.



Have you modified the oil cooler any? Theres a thermostat in the oil cooler that bypasses the core below 140 degrees oil temp. If theres a problem with that, the oil can stay too cold and the thermopellet wont function properly, leading to a loss of oil pressure at the front main bearing.
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Old 04-22-2008, 03:39 PM
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thanks for the response!



it was not blocked off, i did it before i took the pickture!



sooo i hope i found the problem then.



I'll put the engine back together as soon i get of this planform! then we'll se!



rotors are already finished with new sideseals, and with the same NRS cheramic apex seals!
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