smoking & slipping

[daza]

gidday guys i,ve got 1 4 ya.I took the boat out the other day & everything was fine untill applied throttle to get onto the plane & the motor reved up properly then the speed dropped suddenly with the revs remaining normall but no speed just like the clutch slipping in a car.it then starts to smoke hard out untill i drop the revs to just above idle.i think its an '85 or'86 yamaha 90.i,ve owned for 2yrs and have tried looking after it with services etc. hopefully some1 can help, or i,ll have to sell the missus so i can afford 2 get it looked at.....hmmmmm..

 

[Ray Neudecker]

Re: smoking & slipping

Sounds like the hub slipping in the prop.

 

[daza]

Re: smoking & slipping

The smoke is coming from the motor & prop seems fine.

 

[imported_JD__]

Re: smoking & slipping

As Ray suggested, sounds like the rubber hub is slipping. Unless you've stripped some gears or the foward gear is disengaging under load (which you would most probably hear), that's about the only thing it could be. Turn the ignition off and pull the kill switch, remove your spark plug wires from the plugs making sure they are far enough away so there's no chance of accidential starting. Put your engine in gear, with gloves or a rag to protect your hands, see if the prop will turn on the shaft without the motor turning over.

 

[daza1]

Re: smoking & slipping

Gidday JD, i tried your suggestion, and turning the prop, you can feel & hear the piston moving.The rubber hub seems in ok cond. I tried running the motor in a large drum of water and apart from spraying water everywhere there was no smoke.. when i run it with the muffs on it goes into gear fine and revs fine. I just can,t work out a; why slipping when under load, & b;why smoking hard out at the same time. ,it starts fine, seems 2 have good compression, runs fine (usually),& i keep it regularly serviced..<br />any help on the mater would be appreciated, cheers.

 

[Ray Neudecker]

Re: smoking & slipping

Many times the prop will slip only under a full load when the hub is bad. I have never been able to properly test by hand.

 

[imported_JD__]

Re: smoking & slipping

daza1,<br />I'm sure Ray is correct. It would have to be slipping pretty bad for my suggestion to reveal anything. Ray, what is a sure-fire way to determine if the hub is slipping short of trying another prop?

 

[daza1]

Re: smoking & slipping

Thanks you guys for advice, in some ways i hope your right, so maybe all i will have to do is replace the prop without hours of trouble shooting at $60 an hour, which is how much the boat shop charges here.If there is a sure fire way to check short of buying another prop , please let me know, and once again thanks guys for your help, this is a great site and the things you can learn from here are invaluable.<br />cheers.

 

[daza1]

Re: smoking & slipping

p.s. sorry if this is a stupid question, but why would there be alot of smoke coming from under the cover when the hub in the prop is slipping??<br />cheers again.

 

[Snowdrggn]

Re: smoking & slipping

Daza1,<br /> Remove the prop and mark the hub and the prop itself, install the prop, take it for a run to recreate the problem, then pull the prop off and see if the marks have moved in relation to where they started out. If they have the rubber hub is slipping. Easy?<br /><br />Cheers,<br /> Snow.

 

[daza1]

Re: smoking & slipping

bro you the man!!!<br />far out it is easy. i will try it out 2moro.<br />i,ll let u no how i get on, thanx m8.

 

[Ray Neudecker]

Re: smoking & slipping

Snowdrggn is right on the money. A slipping hub is burning rubber like a tire. The smoke travels up the midsection and comes out under the cowling.

 

[Snowdrggn]

Re: smoking & slipping

Ray,<br /> I've never noticed smoke under the cowling on any engine that I have run across that has a slipping prop hub. My response was directed at the issue of verifying whether the hub was slipping in the prop. I usually just take a "paint" marker and put a dot on one flat of the prop nut, and a dot on the exhaust tube of the prop itself, inline with the first dot. After a couple of harsh throttle aplictions, I tip the motor up and check to see if the dots have moved in relation to their original position. <br /><br />Cheers,<br /> Snow.

 

[daza1]

Re: smoking & slipping

gidday snow, i marked the prop & tested today for about 1/2 hour or so down at the boat ramp. Nothing happened, no slip or smoke??<br />the marks were still alligned and there was no trouble getting onto plane etc..<br />(murpheys law i suppose), anyway i,ll test again tomorrow when the weather is better and go out for longer.I talked to the local boat shop & they said if the hub is slipping it wouldn,t fix itself , & that it may be something else, but they don,t know what. any new clues would be appreciated..<br />There is also a problem with putting it into reverse, it sounds like its not getting into gear, & shudders alot when it does go into gear??? makes a grornching sound??<br />cheers<br />daza

 

[mattsaks]

Re: smoking & slipping

Which boat shop do you use? i am in wellington and can put you onto a real good guy if you need!

 

[jafa]

Re: smoking & slipping

Daza<br />Try this , put a block of wood over two of the prob blades and between the cavitation plate. See if you can get a socket over the split pin and onto the prop nut and then , with the motor in neutral , see if you can turn the propshaft by undoing the nut. The split pin will stop the nut undoing off the prop shaft. You might have to put some force on it as the withing seconds of slipping the rubber around the split will have become molten for a few seconds and made a temporary bond again. If you look closely at the rubber to metal contact points you might see ragged weld line.

 

[daza1]

Re: smoking & slipping

kapiti marine usually, but i tried kapiti marine and props in plimmerton (hadn,t even heard of them b4) and they said if the hub fails, it won,t come right. but i went out 2day, seaveiw and there was no prob??<br />Rockhopper cheers 4 advice, i just went out & checked turning the shaft and no joy, i took the prop off again to have a look for ragged weld line and couldn,t see any??<br />I was hoping to go out for a thrash 2moro, do you think this would be ok?? or might end up be towed home?? not a good look.<br />please keep in touch..

 

[sirlespat]

Re: smoking & slipping

What motor is it? If you forget about the smoke sounds more like gearbox or shift linkage adjustment problem. The reverse gear problem is classic for old suzuki's and probably if it is not caused by linkage adjustment you have some gearbox repair indicated.<br /><br />A hi revving no load on a motor may well cause a little smoke under the hood normally (Ive never tried It)<br /><br />good luck<br />sirlespat

 

[daza1]

Re: smoking & slipping

motor is 90hp yamaha. i think its an '86<br />wen put into rev, it feels like it just won,t drop into gear..