Does any one know what would cause the teeth on the stationary gear and rotor to get chewed up? I bought a JDM engine a few year back and decided to rebuild it before installing it. upon opening it I found the front stationary and rotor gear had damaged/missing teeth. The teeth that were damaged were confined to one area on the gear/rotor, not right around the entire gear and rotor. Has anyone seen this and do they know the cause? This was a stock REW engine with out modifications. I find it unlikely that it could be caused from over-rev.

Please chime in with suggestions.
Thanks

 

over-revving yes, or lubrication issues. possible foreign debris but unlikely.

i have seen 2 with the same failures this past year but never before, nor could i pinpoint the cause. one blew redlining in neutral at a standstill, other blew years ago while driving for no apparent reason but i did find that the oil pickup tube in engine #2 had a warped flange and was pulling air and aerating the oil(stock except for 3mm seals). engine #1 had a modified eccentric shaft oiling holes but was otherwise stock. both had been previously rebuilt by another shop, which i do not know the specifics of.

 

Thanks for the reply Karack. I forgot to mention that the the oil from this engine was filthy and looks like it had not been changed for years. Also there was thick sludge in the oil pan.So you are on the money that it may be due to lubrication issues.

 

but in both of these cases it was the rear rotor that failed, not sure the relevance..

this was the first engine failure, no apparent cause but was free revving in neutral and may have over revved somehow.


this one had the oil pickup issue and was sucking air.

 

The bearings on both of those look positively trashed.

Cause or effect or parallel damage from the root cause?

 

from what I see in the pictures leads me to believe that oil starvation caused bearing failure in the rotor leading to unbalance and gear failure. the thought process is if the rotor starts running ecentric on the gear, it will bottom out on the teeth and cause fractures. with the side load on the teeth from each combustion cycle the teeth break, pieces fall on to the next one and failure occures. I have seen bearing failure in many engines, both minor and severe and the end result is always the same.........DEVISTATION. just my thoughts.

 

quite possible but i didn't bother trying to figure it out and possibly damaging newer parts just in order to see if there was clearance issues that caused the teeth to runoff of one another. that is quite possible and the rear of the engine does see the oil last in the factory setup. which leads me to wonder why your front rotor failed over the rear unless your front bearing spun or wore severely somehow.

both engines i simply replaced the back half of the motor/e-shaft and oil pumps and they so far haven't had any issues.