Prop not spinning

[Dominic123]

Hey guys, currently have twin stern drive mercruiser 350 mag mpi.
Was cruising at 1600rpm and suddenly felt a loud thump while trying to accelerate. Prop on the right engine is not spinning and won’t engage into forward or reverse gear. Any thoughts would be helpful. Thanks in advance

 

[ThomW]

Need a little bit more info. You felt a loud thump? Like you hit something with the prop/lower unit?
When you say it won't engage into F/R, do you mean you can't move the shifter into gear...or that when you shift into gear, that engine just revs and the prop isn't spinning?

 

[Dominic123]

Need a little bit more info. You felt a loud thump? Like you hit something with the prop/lower unit?
When you say it won't engage into F/R, do you mean you can't move the shifter into gear...or that when you shift into gear, that engine just revs and the prop isn't spinning?

Did not feel like I hit something with the prop, felt more like built up pressure had caused something to pop off as I was accelerating.

When I engage into F/R with shifter while engine is running nothing seems to be happening or turning.

Although I did manage to lift the right engine up the leg feels a bit loose as I can lift it up and down as well as right to left.

 

[stresspoint]

serial number for the drive would be handy .alpha or bravo ? .

 

[Dominic123]

serial number for the drive would be handy .alpha or bravo ? .

Bravo

 

[ThomW]

Have you checked the shift cable to that engine to see if it may have snapped?

 

[Dominic123]

Have you checked the shift cable to that engine to see if it may have snapped?

Shift cable is still in tact, does go in forward and reverse from the shifter

 

[Dominic123]

Update: leg feels majorly loose as i manage to lift it up and down easily. Not sure if this can be from bad hydraulics ?

 

[racerone]

Check the gear oil.--Post what you find.----Universal joint failed ?-----Perhaps coupling spline failed.

 

[Dominic123]

Check the gear oil.--Post what you find.----Universal joint failed ?-----Perhaps coupling spline failed.

Does have gear oil as far as I’m concerned. Boat was lifted out of the water last week to service legs. Could mechanic possible not have assembled something correctly ?

 

[ThomW]

When you put it into forward or reverse, can you spin the prop with your hand...or does the prop spin freely?

 

[Dominic123]

When you put it into forward or reverse, can you spin the prop with your hand...or does the prop spin free

 

[racerone]

Serviced last week ???-----Call the mechanic to come and check it.

 

[Dominic123]

Spins freely

Serviced last week ???-----Call the mechanic to come and check it.

that is hopefully the plan, just found it out of the ordinary how this could happen without any minor signals of something going wrong. Looks like the drive shaft has possible come out of alignment ?

 

[QBhoy]

Is this a bravo one or 2 ? They have different prop hub arrangements

 

[stresspoint]

Bravo

1,2 or 3 , it makes a big difference to what may have gone wrong.

 

[Scott Danforth]

could be coupling, could be drive shaft, could be gears, could be u-joints, could be something messed up during the work that was done

pull the boat and start investigating

Update: leg feels majorly loose as i manage to lift it up and down easily. Not sure if this can be from bad hydraulics ?

trim hydraulics have nothing to do with driveline

Spins freely

that is hopefully the plan, just found it out of the ordinary how this could happen without any minor signals of something going wrong. Looks like the drive shaft has possible come out of alignment ?

failures happen without warning

driveshafts dont instantly come out of alignment. they do require an annual inspection of alignment as part of the annual service.

 

[Dominic123]

Is this a bravo one or 2 ? They have different prop hub arrangements

Bravo 2

 

[Dominic123]

could be coupling, could be drive shaft, could be gears, could be u-joints, could be something messed up during the work that was done

pull the boat and start investigating


trim hydraulics have nothing to do with driveline


failures happen without warning

driveshafts dont instantly come out of alignment. they do require an annual inspection of alignment as part of the annual service.

The legs were serviced last week, had a jump in the water and the lower unit was moving much more freely than usual. Almost seems like it has completely come loose, had even double checked with the left legs and they not wiggle around at all

 

[Scott Danforth]

The legs were serviced last week, had a jump in the water and the lower unit was moving much more freely than usual. Almost seems like it has completely come loose, had even double checked with the left legs and they not wiggle around at all

and its broken now.

time to pull it back out