Never experienced this before, need your thoughts

[ExLimeyBasher]

Have just replaced the flywheel on my CEN NX46 now when i tighten the flywheel retaining nut the engine tightens up, so i shimmed behind the collet but still the same. All i can think of is that the inner bearing may have collapsed, but i really dont want to do a complete strip down as it took me forever to get this engine leak free (cen engines are notiorius for air leaks) so anyone have any ideas what might be causing this before i strip it down. Also the engine was running fine before the flywheel was changed.

[chrisjw]

To me, it does sound like the bearing.  It may have disintegrated when you tightened up the new flywheel, but that's only my take on it.  Hopefully, someone else can be more helpful.

[Anthoop]

I have to ask the obvious questions first (sorry).....the flywheel is definitely not touching the engine casing/carb.?

 

Other than that I imagine it must be something to do with the bearings...going to need a strip and investigate...once stripped if nothing is apparent then fit the flywheel with the backplate off and piston/liner out.

 

Have you had the bearings out....are they new/old?

[Ian w]

Try putting the old flywheel back and see if it still does if it don`t then there is somthing wrong with the new flywheel.

[ExLimeyBasher]

I thought the flywheel may have been fouling on the crank case so i shimmed behind the brass collet to move it out a bit but still binding. with the fly wheel off and the glow plug out it spins freely with no discernable noise or grinding from the bearings and the front bearing is not leaking. the engine is about a year old but only has about 6 tanks through it since breakin. i will try putting the old fly wheel back on and see what happens. Stay tuned!!

[ExLimeyBasher]

Ok still tight with the old flywheel on, so will invest in a jumbo tube of sealer and do a complete strip down. What is the best way to remove old sealer that is stuck to the various parts?

[Anthoop]

Old sealant (depending on type) usually just peals/picks off.

[ExLimeyBasher]

Stripped her down completly, the rear bearing seemed nice and smooth and tight but on closer insp found the cage where the balls sit had a crack in it, replaced the bearing and all is good now, just hope i can get it sealed 100%.