My boat will go into gear, but when I give it gas the engin revs, but doesn't go faster. What's wrong?

Question

I have an '86 Malibu with a for 351 direct drive. The boat will shift into gear, but when I give it gas, the engin revs, but the boat doesn't go any faster. Does it need a new transmission, or might there be something else that is broken/ worn out

Answer 1

Check the prop. I think you will find that the prop has come loose where it is pressed onto the rubber hub in the centre. Take it off and have it rebuilt.The prop may appear to be ok when you try to turn it, but under high torque it will turn!!Dont get fooled!!

Answer 2

you have done the prop, it has got a rubber bush in it, that the spline runs on, it is deigned to break or shear if you hit some thing hard and to also take out some of the forces from running at high revs in water, just take it to your marine shop and get them to rebush it, it's a good idea to carry 2 props and nut, just for such occasions, if you get into heavy seas, especially following seas, you dont want to be out there on minimum speed to get back, it only takes a couple of minutes to change, re bushing is cheap

Answer 3

Spun prop

Answer 4

sheer pin ok?

Answer 5

does the boat move at all? Generally if the rubber bushing in the prop is bad, it will still grip at idle speed, it is just when you go faster than that when it starts to slip.... if the prop doesn't spin at all then it is the trans, if it spins at low speeds only then you need to have the prop re-hubbed, about 60 dollars