Help

[runabout]

Hi, everyone great to be a new member, I have a 15hp mercury outboard motor that I flush after every outing. I recently found if I spin the prop by hand there seems to be arough feel to it and a grinding noise,does anyone know if there is a bearing behind the prop and could I replace it my self or is it a job for a marine mechanic.would it be very expencive to replace all coments and help much appreciated.

[a boat]

Hi and welcome. First thing I would do is drain the gear oil and see what it looks like and if it has any metal particles in the oil.

You do have a prop shaft bearing, forward and reverse gear bearings and pinnion bearing that can fail, but honestly if it is a US made 15HP Merc (gearshift in the tiller handle) they are a very solid gearbox and do not give us much trouble unless you have a leaking seal which has allowed water to enter and the bearings will not last long then.

Let us know what the oil looks like when you drain it,

Cheers,

Huey.

[Dreamtime]

if it is a US made 15HP Merc (gearshift in the tiller handle)

G,day Huey,

I used to have a 25Hp with the gear on the tiller handle. I recently bought a 15Hp expecting the same setup, however this engine has a separate gear lever (not on the tiller). Why would this be, is the engine made in a different place?

Cheers

Mariner

[a boat]

G,day Huey,

I used to have a 25Hp with the gear on the tiller handle. I recently bought a 15Hp expecting the same setup, however this engine has a separate gear lever (not on the tiller). Why would this be, is the engine made in a different place?

Cheers

Mariner

Hi Carl, that is a shame mate. Yes Mercury own 50% of TMC who make Tohatsu and some of the smaller Mercs are rebadged Tohatus and that is what you have. Mercury have two 15HP available, one the 15HP Super, which is basically the 18HP Tohatsu and then the US made 15HP, which in my opinion is a far superior engine. Nothing really wrong with the Japanese 15HP Merc, but it is built to a price and does not have all the cool features like the US one. No gearshift in the handle, the US Merc has the best tilt system in the 15HP market and the US one runs ALOT smoother and starts like a dream. The 15HP Super goes a bit better, but I think it runs a bit rough and is a bit agricultural in design, but it is cheaper to buy by a few hundred, but as with anything in life "you get what you pay for" and if I was in the market for a 15HP it would come down to the 15HP Johno or the US Merc.

Cheers,

Huey.

[runabout]

Hi, everyone great to be a new member, I have a 15hp mercury outboard motor that I flush after every outing. I recently found if I spin the prop by hand there seems to be arough feel to it and a grinding noise,does anyone know if there is a bearing behind the prop and could I replace it my self or is it a job for a marine mechanic.would it be very expencive to replace all coments and help much appreciated.

Hi, Heuy, thanks for your help, I have drained the gear oil and replaced it and it had no metal particles in it,in fact the oil was like new. the foreward and reverse gear shift is a seperate lever on the side of the motor,the motor is only about 2years old.

[pelican]

I don't know small Mercs very well but here goes

IF there are no metal filings and the oil was good it would be unusual to have a dead bearing but possible.

The 'grinding"or roughness you are feeling may be the dog clutch catching if it is more of a click click click sort of feel. To possibly narrow your problem down _

With the motor not runing and kill lanyard off, spin the prop by hand and move youre gearshift lever slightly towards forward and reverse and if the "grinding" you are feeling goes away it is the dog clutch that is catching.

This could indicate the gearshift linkage is bent or out of adjustment. Surprised but happy for you there are no metal filings in the oil or on the oil drain plug.

If there is no change as you do this it may well be a bearing.

Have you previously changed the oil and did it have metal filings or water in it?

Only other idea is the propshaft is bent.

Spin the prop by hand in neutral and does it spin evenly?. Easiest place to look is where the prop is closet to the gearcase.

If you are mechanically minded or just interested of what's inside your motor have a look at the schematic here

http://www.crowleymarine.com/parts.cfm

Pel

Edited November 13, 2008 by pelican

[runabout]

Hi, pelican thanks for your coments, and thanks for the diagram breakup of mercury motor,regards tackle/bait

[a boat]

Hi, you have the 15HP Super Merc and it could be just as case of the prop rubbing against the inside of the gearcase if the gear oil was fine.

Cheers,

Huey.

[runabout]

Hi, you have the 15HP Super Merc and it could be just as case of the prop rubbing against the inside of the gearcase if the gear oil was fine.

Cheers,

Huey.

Hi, again Huey I have spun the prop by hand and it seems to be just what you said it only rubs in certain spots .Thanks again for all your help your a genius.

[a boat]

Hi, again Huey I have spun the prop by hand and it seems to be just what you said it only rubs in certain spots .Thanks again for all your help your a genius.

Good to hear, after a few hours of running in gear the prop and gearcase will be fine.

Cheers,

Huey.