Transmission failure - boat don't go!

[smbaker]

Today on the lake something failed in the driveline. I didn't hear any kind of a clunk or other noise, but the engine immediately raced in RPM and I shut it down. Afterwards, when I shift into gear, the boat don't go anymore. It's also not pumping cooling water anymore; Fortunately I managed to limp it back on a trolling motor (a 4 hour trip, but better than spending the night on the lake).

I checked the shifter cables and they look fine so far as I can tell. Shifting into gear and manually spinning the prop from the outside, I am able to feel some resistance, but it's certainly not connected to the motor.

I have a service manual somewhere that I'll dig out, but I was wondering if anyone had an idea of the most likely cause? It's a 1993 Bayliner, 4.3 liter, Mercruiser motor and stern drive.

Thanks,
Scott

 

[mr 88]

Re: Transmission failure - boat don't go!

Try posting in the Mercruiser forum.I would guess that the coupler is blown out.The drive shaft from the outdrive ,which is hardened steel slides into a aluminum splined coupler which has a rubber ring in it.That rubber absorbs some of the stress when shifting gears.If your bellows is bad, water intrusion into the U-joints will follow.When your joints go bad it takes out your gimbal bearing[the part your drive shaft rides on through the transom]. Once that is taken out the coupler takes the misalignment and after a while the splines get chewed up.I base this on you saying it is not pumping water,if it was pumping water I would first check for a spun prop,but that is not the case.
I had one go bad on a inline 6 and was able to change it without pulling the motor.Not sure how yours is set up but be prepared for the worst unless you are mechanically inclined.You can be walked through the procedure in the Mercruisre forum. NAPA used to sell them,the may still if not available on here.

 

[Faztbullet]

Re: Transmission failure - boat don't go!

It could be the coupler or the upper gears have went out due to lack of oil.......

 

[smbaker]

Re: Transmission failure - boat don't go!

Try posting in the Mercruiser forum.I would guess that the coupler is blown out.The drive shaft from the outdrive ,which is hardened steel slides into a aluminum splined coupler which has a rubber ring in it.That rubber absorbs some of the stress when shifting gears.If your bellows is bad, water intrusion into the U-joints will follow.When your joints go bad it takes out your gimbal bearing[the part your drive shaft rides on through the transom]. Once that is taken out the coupler takes the misalignment and after a while the splines get chewed up.I base this on you saying it is not pumping water,if it was pumping water I would first check for a spun prop,but that is not the case.

Hmmm.... This does sound plausible. There wasn't any noise when it stopped working (no clunks or snaps) so it would have to be something fairly soft that went.

I'll try posting on the Mercruiser forum (I thought I had! but must have clicked Mercury Outboard by mistake).

Unfortunately, I couldn't find anywhere in my Clymer manual that describes this coupler. Lots of detail on the Alpha One stern drive, and some motor rebuilding detail, but no decent diagram of what's coming out the aft end of the motor.

Scott

 

[cr2k]

Re: Transmission failure - boat don't go!

Engine coupler, or vertical drive shaft snapped.

 

[Volphin]

Re: Transmission failure - boat don't go!

I agree with the engine coupler. Most likely culprit.

V

 

[brhodes]

Re: Transmission failure - boat don't go!

I've seen a suggestion previously to scribe a line from the shaft onto the coupler, run it (may have to be in the water, just on the trailer), then see if the scribed mark is still lined up, if not, coupler is bad. just an idea, good luck

 

[Bondo]

Re: Transmission failure - boat don't go!

Today on the lake something failed in the driveline. I didn't hear any kind of a clunk or other noise, but the engine immediately raced in RPM and I shut it down. Afterwards, when I shift into gear, the boat don't go anymore. It's also not pumping cooling water anymore; Fortunately I managed to limp it back on a trolling motor (a 4 hour trip, but better than spending the night on the lake).

I checked the shifter cables and they look fine so far as I can tell. Shifting into gear and manually spinning the prop from the outside, I am able to feel some resistance, but it's certainly not connected to the motor.

I have a service manual somewhere that I'll dig out, but I was wondering if anyone had an idea of the most likely cause? It's a 1993 Bayliner, 4.3 liter, Mercruiser motor and stern drive.

Thanks,
Scott

Ayuh,... Pull the outdrive, 'n see what moves, 'n what don't....

6 nut's 'n a couple of clips, 'n it's off,...