Possible Gearbox Damage

[nosliw]

Hey Raiders,

About 5 trips ago I remember getting some line caught in my propeller in which I pulled until it came out. But after my last trip I saw some line still stuck in the propeller so I decided I would take it apart and clear it of any remaining line.

I just took the propeller off and to my suprise saw a sh*tload of line stuck in there. There must have been 20m+ of braid caught there, probably even more than that. I have now cleared it of any line and also noticed a bit of a burning smell not overly strong but if took a breath I noticed a slight burning smell.

Now I have heard that tangled line can cause gearbox problems is there anything I can do to check?

Is the burning smell just normal exhaust residue or should I be worried?

And lastly I tightened the propellar back on quite tight is this normal procedure or should I loosed it a little?

Any help would be greatly appreciated.

[pelican]

Hi

A prop nut does not need to be very tight just firm so that it sits solid on it's boss. The split pin or tab washer or nylock nut keeps it there and the splines take all the torque and stop it spinning on the shaft.

Always grease the splines with a finger full of quality grease.OMC triple guard seems to work for me and doesn't go grungy and hard like most other will so it is easy to wipe off and re-apply every 6 months or when I suspect there is line around my prop. I just use a lump of wood between the cavitation plate and the broad edge of the prop and a shifter / prop spanner and tighten till firm. Don't forget to renew the bendable tab or splt pin as many a prop is lost when these are not replaced.

When the prop is off you will see a black rubber seal ( like a thin rubber ring) where the shaft goes into the gearbox.It is that rubber seal that stops water going in to the gearbox and oil coming out. Behindg the seal are the bearings that keep the shafts and gears running smoothly in a oil bath.

If you look at that seal on bad cases you can see that it is physically torn or abraded.

Water can be easily checked for in the gearbox by undoing the top srew bung with a extra large screwdriver and checking the oil level ( in case it has leaked out) and also that the oil isn't emulsified ( white and frothy). It gets emulsified when water enters the gearbox and the oil loses it's lubrication quality and the gearbox either rusts or seizes. If it is not white and is still up at the bottom of the drain plug when the motor is vertical you are OK. If the oil is white and emulsified you need to get it fixed and pressure tested as it will most likely be the bearing carrier prop seal that needs replacing.

Check with your particular motor dealer if you need to replace the copper plactic washer or oring under the bung each time you open it up and buy a few so you can check it regularly as many are single use and will never seal properly if is reused hence letting water in or oil out.

If you don't get your motor serviced regularly I would do a gearbox oil change ( every 50hrs or 100 if using a full synthetic oil) and then you know it is done. Dealers will have a small oil bottle of the corrct oil with a adaptor that goes into the bottom drain bung hole. Drain the old oil out by removing both bungs. Clean with rag well around bung holes and clean the bungs as many have a magnet in the bottom one to collect any metal shavings. Attach oil container to bottom bung with motor vertical and squeeze till it fills the box from the bottom up and oil comes out the top bung. Put in top bung with new sealing washer and tighten. The oil container then gets unscrewed and the oild stays in until you get the bottom bung and new washer tightened. Job done.

The burnt smell is probably just combustion smells from the exhaust

While you are doing the work around the prop check the condition of the prop edges for nicks and dings and have a look at the rubber hub and check the burn't smell isn't because it has been spinning on the rubber shock absorbing hub. Also feel the movement and spin the prop shaft and listen for any grinding or rough noise or excess in out or sideways play as they are all early warning signs of possible problems in the future. If you do it every 6 onths you will pick up a lot of problems before the gearbox goes bang unexpectably one day.

Edited January 29, 2009 by pelican

[achjimmy]

Hey Raiders,

About 5 trips ago I remember getting some line caught in my propeller in which I pulled until it came out. But after my last trip I saw some line still stuck in the propeller so I decided I would take it apart and clear it of any remaining line.

I just took the propeller off and to my suprise saw a sh*tload of line stuck in there. There must have been 20m+ of braid caught there, probably even more than that. I have now cleared it of any line and also noticed a bit of a burning smell not overly strong but if took a breath I noticed a slight burning smell.

Now I have heard that tangled line can cause gearbox problems is there anything I can do to check?

Is the burning smell just normal exhaust residue or should I be worried?

And lastly I tightened the propellar back on quite tight is this normal procedure or should I loosed it a little?

Any help would be greatly appreciated.

Same thing happened to me over xmas although i removed the prop as soon as i got back home from the ramp. i cleaned the seal area and checked the gearbox oil and then left it there with the prop off to see if the seal leaked. If the seal dont leak and the gearbox oil dont emulisfy you should be ok, unless damage to the seal is enough to show up after a few hours use.

[pelican]

We seem to pick up line from wharfs and pontoons where shore based fishermen have either dumped line into the water or been broken off. They either don't care or have never owned a boat the guys who dump into the water. Can get very expensive for the boat owner. On a shaft drive we picked up a longliners line that had been disgarded at Sydney heads and couldn't believe how much we wound onto the shaft. Dived on it in Watsons bay but knive wouldn't go near it. Ended up slipping the boat and the choice was the angle grinder until the last layers which we used the oxy to burn it off. Couldn't believe how tough the stuff was and how tightly it bound on and you could see the marks where it cut into the bronze skeg as it wound on.

[nosliw]

Thanks for the detailed reply guys!

I will get the gearbox oil checked out.

[a boat]

Hi, a competent outboard tech can drain the gear oil and pressure and vacuum test the gearbox to confrim any damge to the propshaft seals. I remove my prop every six months for this reason and grease with triple guard.

Cheers,

Huey.