1990 maxum 3.0l thumping/crunching noise from motor

[jimmyebay]

ok. 1990 maxum with 3.0l. have heard some odd noises on last boat trip this year. was winterizing. ran boat with trim down out of water with hose. could here the noise towards back of motor or front of outdrive. its a rotation thumping noise and then will also make a bad rotational sound(like a bad deep growl noise.) i did see a small pile of rubber at back of motor where out drive shaft goes into motor. pulled outdrive off and inspect gimble bearing. smooth and tight like new. ran boat quick with outdrive off. same noise. there a rubber joint on that flywheel?? those fail often?? engine alignment cause failure?? thanks

 

[NHGuy]

Re: 1990 maxum 3.0l thumping/crunching noise from motor

The coupler that the drive shaft engages is on the flywheel and uses rubber between the flywheel side and the driveshaft spline. So yes there is rubber.
I'd remove the belts and run the motor very briefly to see if the sound is still there. Also get an alignment bar and check the coupler with it. And yes, engine alignment can cause coupler failure. That's why you use the aligner bar, to avoid the failure on the next coupler. Couplers break when the drive shaft is in the coupler imperfectly aligned.