That dreaded bang sound

[sistack]

Hi I'm hoping someone can point me in the right direction or just make my bank account feel better
the boat is a 1800 sr3 but the engine was replaced in 2011 with a 4.3 v6 mpi and alpha1 gen 2 stern drive
I was out on the river yesterday and hit something in the water and hit the skeg and prop and there was a loud bang and lost all drive
it sounded like a 4x4 drive shaft breaking in the diff ( if that helps anyone )
My question is which shaft will break first ?
thanks for reading
and looking forward to your input
Simon

[donald]

Drive shaft, engine coupler, cross bearings (u joints).
Just my thoughts.
Don

[sistack]

I was thinking u joint too
thanks

[mmwjr]

So you have no motion even at low rpm? With the engine running is there any noise? Also look to see if the driveshaft is turning on the rear of the engine into the transom assembly. Remove water inlet hose to see if it’s pumping water, if so then you know the vertical shaft in drive is turning the impeller and the dog clutch is blown.

[sistack]

Thanks Mike
no strange noise and no movement at all

Simon

[sistack]

thanks for all the suggestion
I took the out drive apart and it had broken the lower unit drive shaft ( it twisted the splines off the end of the shaft and bent and started to twist the prop shaft
So i replaced the complete lower unit but now i have a new problem
when i put it back together i have it in forward gear and the prop would lock in one direction so all good and finished the assembly
then i put it in the water and stared it out of gear then put in forward and it moved then i needed to stop so i put it in reverse now when i put it in forward it just revs but no movement and reverse still works
Would this be a shifting cable adjustment problem?

[mmwjr]

With the engine off put the shifter in forward and try turning the prop counter clockwise, it should not turn. The turn clockwise and it should turn freely. Now put the shifter in neutral and it should turn freely either direction. Last put it in reverse and it should turn freely counter clockwise but not clockwise.

Post results.

[sistack]

It locks in reverse but not in forward but you can feel the drive dogs are just touching you can hear it click

[mmwjr]

Do you have neutral? If no the lower unit slipped out of gear as you installed it. If yes i would disconnect the lower shift cable from the shift bracket on the engine and see if you can manually shift it into forward and reverse by pushing and pulling the end of the cable while holding firmly the cable jacket.

[sistack]

Thanks I'll try that if I can shift by hand
What would the next step be?

[mmwjr]

Originally Posted by sistack

Thanks I'll try that if I can shift by hand
What would the next step be?

Verify helm shifter is moving the shift bracket in both direction. Worst case is a defective lower unit.