I have a 1998 four stroke 40 hp motor(carb/3 cylinder) that sheared the flywheel key and allowed the cam gear to spin as well. I wasn't on the boat when this happened. The engine oil looked good, and the gearcase oil looked good. I cleaned up the crank and flywheel surfaces, replaced the timing belt and timing gear, torqued the flywheel down to spec, and timed the engine. It ran perfectly on a hose, both at idle and higher RPMs. I launched the boat and idled out of the harbor. As I was throttling up in gear the engine seized. It would immediately spin again, but had sheared the flywheel key, so the timing was off and wouldn't start. I put it back together again and again it will idle. I have pulled the gearcase off to see if anything could be binding. I have no excessive play anywhere in the gearcase, crankshaft, or camshaft. I have no signs of burned oil, no signs of silvery oil or chunks of metal.
Can anyone help me identify the cause of this? I had thought possibly crank bearings, or a gear tooth in the lower unit causing the abrupt stop, but can't find any evidence to support either idea. I can run it with the gearcase removed, but I can't put a load on the engine to replicate the problem. Any help would be appreciated, I've been chasing this around for a while now.
Thanks
Can anyone help me identify the cause of this? I had thought possibly crank bearings, or a gear tooth in the lower unit causing the abrupt stop, but can't find any evidence to support either idea. I can run it with the gearcase removed, but I can't put a load on the engine to replicate the problem. Any help would be appreciated, I've been chasing this around for a while now.
Thanks
