No power- Stern drive shaking

[Rookie77]

Hi!

I have à problem that seem to appear after my boat has been in dock for several days and not been used.

What happens is that When driving 10-15mp my boat loses power and my stern drive starts shaking, at the same time my steering gets very easy, allmoast as if I had power steering but I dont.
After bleedin trim system it seems to go away.... But comes back a few times every season.
Maxum 3.0 Mercruiser lx from 94.

Any idea? Same issue?

//J

[mmwjr]

Welcome aboard!

When the engine looses power are you loosing rpms? How long does this last? Any noises associated with this issue? How are you bleeding the trim system? If should self bleed. Are you loosing trim fluid and how often do you add?

[Rookie77]

The motor gets high rpm and that together with the Stern drive shake makes me lower the throttle.

It lasts untill I bleed my system by raising the sterndrive up and down seveal times.

No more noise than from running motor.

Yes, I loose à small ammount of liquid, but I dont have servo steering so I cant make sense of it...

[Phillbo]

Are you sure your trim is not too far up and you are cavitating?

[mmwjr]

If the rpms suddenly increase without you increasing the throttle one of three things are happening. Trimmed to high allowing prop to come out of the water. Bad prop hub (spun) loosing grip between inner and outer hubs. Or spun engine coupler.

[Rookie77]

Im not sure about the rpm, it might just be the shake that makes me lower the throttle....

How Can one explain the suddenly easy steering?

And that after bleeding done steering is hard again.

[Rookie77]

Im not trimmed to high, Im changing prop today but that dont explain the steering and the shake?

Thanx for Your patience With me and my english...

[mmwjr]

Your English is fine but please try to pay attention to everything the boat is telling you. I’m really interested in knowing if the rpms suddenly increase. As I mentioned this would be either a spun prop or engine coupler. When this occurs the lack of load on the engine will cause some vibration also since the prop isn’t spinning as fast the prop wash effect goes away which will make steering easier.

[Rookie77]

Your reply i totalty logic, but what I Dont understand is the steering, its loose as if i had servo on even without power on propp...
After bleeding its back to hard again.
Does tilt and trim fluid pressure effect steering even on old boats without power steering?

[mmwjr]

Originally Posted by Rookie77

Your reply i totalty logic, but what I Dont understand is the steering, its loose as if i had servo on even without power on propp...
After bleeding its back to hard again.
Does tilt and trim fluid pressure effect steering even on old boats without power steering?

The trim system should have no effect on steering.