Mercruiser outdrive fail?

[cHic et Nunc]

Hello forum,

We have a 2008 SeaRay 195 4.3L MPI with Alpha One outdrive.

Putting it back in the water after winter storage the engine runs fine but in drive it hesitates and does not come up to speed.
After a while the boat drives fine, driving around 2000 rpm we feel a big clunk, as if we hit a piece of wood..
Boat slows down, impossible to get it back up to speed with engaged drive.
We can luckily limp back to port at very low speed, speedometer stays at 20 MPH even at this speed.
No damage to the propellor.

Does anyone have an idea what could be the cause?

Thanks for your advice,

Peter

 

[spannerman]

Are there any noises from the drive when the engine isrunning in neutral and you turn the steering to full lock, if so this could be the transom bearing or universal joint. Try running it on muffs on land and listening to the drive as you select gears. Either way you need to have the drive off to inspect the U/J and drain the oil from the drive to see if it is contaminated with metal particles indicating gear failure. Rotating the U/J shaft and operating the gear linkage on the drive should show if there is any roughness from internal damage.

 

[cHic et Nunc]

Are there any noises from the drive when the engine is running in neutral and you turn the steering to full lock, if so this could be the transom bearing or universal joint. Try running it on muffs on land and listening to the drive as you select gears. Either way you need to have the drive off to inspect the U/J and drain the oil from the drive to see if it is contaminated with metal particles indicating gear failure. Rotating the U/J shaft and operating the gear linkage on the drive should show if there is any roughness from internal damage.

Thanks for the advice, I will test this early next week and also take the drive off to inspect...

 

[QBhoy]

If you hadn’t mentioned the big clunk...I’d be assuming one of a couple of the usual issues at this time of year. As in, water in or bad fuel...the infamous mpi terrible distributor cap failure or worst case...one of a couple of issues that can be caused by frost damage over winter.
Personally I’d firstly take the prop off and inspect the sacrificial hub hasn’t sheared in the prop. Then I’d take the plugs out for a look. Also take the fuel filter off and pour the contents into a glass to see if water gathers at the bottom of it. One of these should tell the story for sure.

 

[Restoration man]

My old mercruiser had a stainless prop with some square plastic thing between the prop and the shaft that I assumed was designed to let go if you hit anything to save the gearbox if that’s faulty it might make banging sound?? And could also slip so would prevent boat from reaching proper speed , just a thought

 

[cHic et Nunc]

Took prop off to look at the sacrificial hub and it is undamaged.. did find woodbits blocking the pitot hole so must have hit a log .. still have toi run it with mufs on, waiting for the snow season to end