1998 Honda 75 Outboard - Slipping as RPM's Increase - not the hub - Suggestions ???

[redr2]

I have a 1998 Honda outboard (75hp). Was doing great one day cruising a 20 knots when all of a sudden the rpms raised. I killed the power and then power it back up and every time I got over 5 knots the rpms were increasing with very little speed. I crept back into shore at about 4 knots for the remaining mile or so.

Figured the hub had slipped. No damage to the prop but I popped it off and even took into a local marine shop to order a new hub. He popped out the plastc sleeve and it looks great. No signs of slipping and no cracks. He would not sell me a new hub kit as he figured its not hub slip. I now have the lower leg off but not yet apart as I do not have the required pullers.

Any thoughts of what might be broken in there??? drive shaft splines look good and the gear oil (which was changed a few months back) came out clean? Thoughts!!! ?? thanks!!

 

[Sea Rider]

Personally would put that prop back on previously marked to perform a hub slip test on a wot spin to be 100% sure about its peak performance before venturing into wild blind guessing....Must the hub be adjusted tight with shaft's hardware for the prop to perform satisfactorily ?

Happy Boating

 

[redr2]

I dropped the leg and was going to dismantle but I don't have the pullers required anyway. I just need to re-install the water pump. The nut and matching lock washer was on good and tight when I removed the prop. If the hub was slipping.....shouldn't I see signs on the plastic parts, like cracks, rounded edges or even scratches. Even the grease looked like nothing had shifted hub wise?

I bought the boat in May. Its always made a slight grinding noise of gears meshing when puting it in reverse. Forward was always silent going into gear. Not sure of that changes anything?

 

[Scott Danforth]

its either prop slip, or you have something broke, such as vertical driveshaft splines, or your gearset is toast. not much else in an outboard.

could you have had weed fouling on the prop?

 

[hondam]

Before you tear it apart double check the hub as suggested also try adjusting the shift cable. Cables can stretch over time.

If neither of those help it is your clutch dog and possibly forward gear that is worn. Rounding the corners of the clutch dog will cause that.

 

[redr2]

Thanks. I will have to conduct some more tests. Can someone confirm what a hub looks like after its been slipping (upon dissassembly and examination). The marine mechanic would not even sell me a hub kit and was certain upon pulling my prop apart that it had not been slipping.

I am nearly ruling out the stretched cable as it was clearly in gear (maintaining 5 knots for about a mile). And no gear lash was heard.

So to confirm also, its possible that badly worn parts in the gear box can cause slip similar to that of a slipping hub? Its just odd that there were no metal shavings in the oil.

Thanks for all the replies to this one. I will post updates.....

 

[Sea Rider]

With previously marked visible line or dots as in example. Put prop back on with tight adjusted hub by means of prop nut & hardware.



Go for a wot spin lightly loaded for some minutes, pull prop, check if line or dots has moved from originally drawn, if so, hub is not doing its homework right.

Happy Boating

 

[redr2]

thanks, I can try this with the lines, but won't there be visual damage to the drop in hub once apart if slipping? Mine looks fine? Logic just tells me I would see the squared off edges rounded off or cracked.

 

[Sea Rider]

You can only tell if having a hub slip under water trial, seeing it visually won't say a thing as the prop must be spinning to have a spun hub. Before going any further checking other engine issues you must know excat prop working cond. Does prop manufacturer specifies shaft's nut torque adjsutment, if so, probably out of proper one ?

Can't tell if there will be visual effects on hub if proven being spun, we only work with traditional vulcanized rubber hubs seen on most Tohatsu OB's we sell.

Happy Boating

 

[steelespike]

A waterproof line across the hub and body of the prop The inner portion of the hub may spin. Your line needs to include that part.
I don't expect the outer portion of the hub to slip within the body of the prop. The line of course will indicate if it does.

 

[redr2]

Update here and a Q. SO was not the hub slipping. Also dropped a grand on having the leg torn apart. All new seals and all. No issues in the leg, They can't really say what it was but told me to check the cables. Waiting on a new steering cable/helm before I get it back on the water....seems like I am no farther ahead though, any other ideas? thx

 

[Sea Rider]

Disconnect cable from OB, while at idle manually shift fully to forward gear, throttle and see what happens ? If same cond, isn't cable..

Happy Boating