2003 Mercruiser 5.0 just revs but doesn't move above low throttle

2003 Mercruiser 5.0 just revs but doesn't move above low throttle

Has anyone experienced this before? or have an idea as to the fix?

I have a 2003 Chapparal SSi220 with a Mercruiser 5.0. We were cruising at about 3500 rpms and the boat stalled. It started right back up but would not "go". I ruled out the throttle kill switch/cord and I did not hit anything. When I open the throttle more than ~10% the engine just revs without moving the boat.

The idle is normal, low throttle described above functions normal, reverse functions normal, and the boat has not stalled after the initial time. I made it back to dock and once out of the water I inspected the drive. Did not notice any damage or debris on the drive, prop, etc.

Any ideas would be great. Thank you in advance.

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

Is it overheating? Yes= bad coupler
No: bad prop hub, no oil in the drive,

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

Nope, not overheating. I have noticed the speedo remains on 0 and does not operate lately. Of course everyone has told me mercruiser speedos are not accurate and delayed in displaying any speeds but it does not work at all ow. Everything else is normal on the guages and as far as boat / engine sounds nothing out of the ordinary.

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

what about the oil in the outdrive?

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

If you can go hard reverse without the 'slip', and not forward, then it's probably something within the upper outdrive housing that's messed up.

But, chances are its a spun prop hub. I've had it happen, it feels like a worn out clutch on a manual transmission car.

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

I will have to check further for oil and if the prop spins by hand while in gear with the engine off. That will have to be tomorrow :S

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

The prop won't spin by hand. Sometimes you can jump on it and it won't move, but you'll still have that same spun prop hub problem. It takes an enormous force to spin it.

Chalk it. Meaning, make a mark with a sharpie or something that shows up on the hub and prop, in alignment, and then go in the water and get it to slip. Check your marks. If they no longer line up, there's your problem. New prop or go get that one repaired cheaply.

Re: 2003 Mercruiser 5.0 just revs but doesn't move above low throttle

Most likely prop hub or engine coupler.

Reach back as far as you can behind the motor (not running). If you can feel the shaft and you come up with a very sticky black gooey mess its the engine coupler requiring drive and engine removal.