30 hours on a Baja Force 265, 454, stripped the splines out of the coupler. Was new 30 hours ago, I didn't grease it during that time, alignment was good when installed. Mercruiser says use their special grease, ONLY !!. I guess they weren't kidding. So,,,,,,,out she comes.

What are you running for front motor mounts?

Replace the driveshaft this time while you're at it!

Doubt the non Merc coupler grease was your problem here.

Something else is wrong. Couplers should last a heck of a lot longer than 30 hours. Grease doesn't have anything to do with that. Something is out of alignment. Did you install the coupler or did a Merc service. If it was service then I would take it back and have them redo it -= no charge.

I had a coupler go out last year but found out the prior owner _ we think- thought he was tightening the motor mounts and screwed up the alignment.

I was told that every 100 hours to check the motor alignment and grease the splines every 50

3pointstar

one of the biggest coupler killers is a bad transom. With the drive level hop up and down on the cav plate and have someone watch the surface of the transom just above the transom assembly.

Was aligned with Merc. tool, front mounts are the cast merc. 2 bolt feet, with the jack screw . Will try the jumping thing to check possible transom flex .Drive shaft spline looks pretty good, a little worn. Reading older threads, some members felt lack of grease was a major cause of failure, along with mis-alignment. I bought a new one to prevent this scenario.
Can't check alignment now, as teeth are gone, but I was very careful installing.

daleroger -- I hope you don't think I was ragging on you - if so - I apologize. I'm not a mechanic but I can't see how grease could play that much role in a coupler wearing out. If the splines are aligned along the length of the shaft-- all the grease should do is lubricate the movement in and out of the drive shaft. I has to be alignment or as another member posted flex in the transom - it can't be the grease - that flys in the face of logic

good luck

3pointstar

I would have to agree with that. there should be no sort of movement in the coupler and shaft that would require lubrication other the assembly or disassembly, also in that short of a time there would have to be another cause. try sounding the transom with a light tack hammer you'll know when you hear pitch changes or hallow sount as you tap across it.

force 265 ain't a young boat. dave is probly right. he is wrong when discussing hulls about as much as brett is when talking props or bob madera when discussing cams. if so, best bet is change coupler and drive it like it's a bayliner for the rest of the season...full throttle no mas.