Uh oh

[petern]

Cruising at 3400 rpm today, suddenly lost propulsion......it felt and sounded like cavitation...I reduced throttle to 2000 rpm and limped home......speedometer also ceased operating.....when I increased throttle, same symptoms, back to 2000 rpm, no problem.......didn't have time to really check anything at marina, that's tomorrow's project....any ideas in advance of that more thorough checkup?

 

[Nehalennia]

Coupler?

 

[petern]

good question. will let you know after I figure out what and where the "coupler" is......

 

[LockedupXJ]

The coupler is basically a big rubber peice that bolts to the flexplate on the back of the motor and transfer the power to the driveshaft.

 

[Firerooster]

Start simple first....anything stuck on your drive that may cause cavitation? Mine did same last year.... Jumped in water and pulled a plastic bag off the front of the lower unit. Obviously turn off motor before jumping in....

 

[Spookeay]

Could it be a spun prop hub? Hummm!

 

[wileecoyote]

I was thinking the same thing Heather. I think I would borrow a prop from someone before I would check the coupler.
At 2K RPM are you still on plane? Does it cavitate before when you are throttling up to get on plane? I would think that would be where the prop hub and coupler would be under the most torque to spin.

 

[petern]

Thanks to all for you response......gives me plenty to keep me entertained today.......

 

[Dave S]

First off there is no prop hub on Bravo 3 props so that couldn't be the problem. A bad coupler could be the problem but that will typically give you the smell of burning rubber. Did you notice that? Did you get an alarm before the boat slowed down? If so was there any message on the Smartcraft LED panel?

Dpending on the answers to those questions we may have other advice for you. The bag over the lower unit could be a possibility but I am not sure why that would have caused a major slowdown. Did you notice your engine temperature operating above normal? If so then the bag might explain it and would certainly explain why the speedometer stopped working. Other things to check are low fluid in your outdrive bottle. That will throttle back the engine as well.

 

[chumbley]

Not the coupler or the prop - since it's working fine up to 2000 RPM's. In my experience, couplers go completely (and suddenly), and smell badly of burned rubber.

Sounds like engine control is limiting RPM's due to a problem it detects. Check temps, oil pressure, etc.

 

[petern]

Many thanks for all the posts......Good news (for me) I noticed some marks on the newly painted lower unit. Bottom line is that the "bag"/seaweed theory seems to have been accurate......apparently, after shifting into reverse, whatever had been caught around the lower unit came free......speedo now works, and we spent the day on the bay with no further complications......BTW, I had throttled back to 2000 manually when the "cavitation" occured......no false sense of security however, the next BOAT (Break Out Another Thousand) lurks in the next cove.........

 

[Firerooster]

Awesome glad it was simple and low cost! Have a great summer

 

[petern]

BTW, guarding against a false sense of security. Nothing is simple and low cost in this game!!