question

[davey g]

hi i have a problem with my mercury blueband it starts and everythnk is fine i put it into gear and throttle slowly and it moves us but when we throttle harder the engine revs realy fast and the boat doesnt pick up any speed it has just started doing this just wondering if any1 has any ideas wot the problem could be i wondered if it could be the clutch gone but dnt no if they hav 1 or what any help would be realy appriciated.

[Les]

could be your prop isn't spinning because either the shear pin had snapped (if it has one) or the (can't remember the right name for it) rubber thingy that slips inside the prop that protects it if you hit something is shagged....

blueband merc is pretty old now, what size is it?? (HP)

[big_sean]

try looking at your prop and see if it is spinning then if now check the prop bush first if ok then its gearbox
always work from the outsid in



sean

[Charlton]

where'd me post go, answrede you almost straight away
Davey, take it engine is on the boat on a trailer. Put the engine in gear and try and turn the prop, if it turns without the drive shaft turning it is most likely the shear pin, but as Sean says, check the bush. If the drive shaft turns then it could be the clutch slipping at high revs, but more likely problems with the drive shaft. gear box, drive shaft connections, it could even be snapped. But again as Sean says, work from the outside in over, and if you do have to dismantle the drive/gear box make sure everything goes back in the same alignment, parts will be marked, or should be but can still be put back wrong, i.e. back to front sort of thing, better still get somebody else to do it.

[Charlton]

just one Q Davey, you haven't been running the engine in gear with the prop out the water, have you?

[davey g]

the pin sits just under my nut on the prop it has 2 bits cut out of it which drops on to 2 pins on the propella they are fine like a say its running wen in slow then soon as you try and accelerate it just stays at the same speed but reving realy high

[davey g]

just one Q Davey, you haven't been running the engine in gear with the prop out the water, have you?

no never run it out the water alway in water it was fine the first time we tried it now it'll go slow but as soon as you accelerate it revs hard but at the same speed

[davey g]

iv been told also it could be my propeller apparerntly there is a rubber on the inside and if it had been locked up on somethnk it could of worn it wich under a lot of force it would just spin slowly whilst the prop is going hard

[Charlton]

the reason why it is reving high is there is no resistance on the prop, did you try turning the prop by hand when it was in gear, it shouldn't turn freely if at all, well at least mine didnt. You are loosing the drive from the gear box to the prop somehow, or for some reason there is no power getting to the gear box from the engine to turn the prop. Might sound daft, just check something, take the lid off and make sure the flywheel nut is tight. If you have a tank to run the engine in you could try running it and watching the flywheel and nut. If its loose duck. I once had an old engine that came with a boat I bought, it did something similar, it was drawing air in somewhere, but as well as revving high it also spluttered a bit. It went straight away part ex for a new one. Davey could be loads of things, bet when you find out it is something simple.

[mark]

Alan's hit most fot he nails on the head there, if the engine is revving but there's no power getting out of the prop, that more than likely wher the problem lies.

not sure if bluebands had shear pins or were splined. if its splined, the problem could also be the prop itself. some merc's had big rubber bushes in side the prop, and inside the bush is the bit that goes onto the the gearbox shaft

the rubber might possible have perished, at low revs there might be enough friction in the chewed up bush to turn the prop but as the revs build it just slips

[Charlton]

Davey
just another Q, when you, dont know what your throttle system is, when you turn throttle handle on tiller or push lever on remote control can you feel or hear engine/gears engage. Engine should jump.

[davey g]

Davey
just another Q, when you, dont know what your throttle system is, when you turn throttle handle on tiller or push lever on remote control can you feel or hear engine/gears engage. Engine should jump.

has no tiller arm it is done by remotes yes when put into gear the engine jumps definatly engaging it drives av noticed the centre of the propeller with the splines stay still but the propeller itself has movement on it when in gear with pressure on as if the rubber could have gone wich is why it moves me slowly then when rev harder it is under 2 much strain it slips.

[Charlton]

it certainly seems as if the prob as marc suggested is at the bottom end, not having had much to do with merc, i was warned off them many years ago when first buying a boat, dont know if they have improved since then, marc seems more clued up on them especially about the bushes, as he says they could be perished.