1976 6 hp Evinrude "slipping or over reving" coming up on throttle.

[hingeman]

We went duck hunting this morning at a lake with lots of tree tops. Afterwards, when coming up on plane, It was like the clutch slipped every now and then and would over rev. In open water, after it slipped a couple more times, it ran fine at full throttle. "Coming up on plane", nice try, its a 6 hp pushing a 14' aluminum boat. I've had it for years and never did anything to the lower end except water pump and changing fluid. Any ideas where to start? Scott

 

[racerone]

Try another prop.-----And myself I would not hesitate to pull the simple lower unit apart for inspection.----In my opinion the bronze bushing above the pinion is not up to the task,-----Perhaps it is egg shaped leading to issues with gear mesh.----Could be the clutch dog and forward gear edges worn as well.----Or issues with the shift rods not prperly assembled.----Simple to diagnose but I can not see / touch your motor.

 

[hingeman]

Try another prop.-----And myself I would not hesitate to pull the simple lower unit apart for inspection.----In my opinion the bronze bushing above the pinion is not up to the task,-----Perhaps it is egg shaped leading to issues with gear mesh.----Could be the clutch dog and forward gear edges worn as well.----Or issues with the shift rods not prperly assembled.----Simple to diagnose but I can not see / touch your motor.

Thanks for the advice racerone. I just dug up the service manual and was looking at it. It does look simple but you know how that goes. Not always so simple! I hate to tare it apart in the middle of duck season but I'll see how that goes. I'll start with the prop. It's the original. Thanks again for the help. Scott

 

[racerone]

Was overhauling those when I was a teenager.----Nothing to them.

 

[hingeman]

Was overhauling those when I was a teenager.----Nothing to them.

Can the prop slip on the hub? The diagram shows an 0 ring in front of the prop but I don't see one. Would that be between the prop and the hub? Is there a way to check the hub? The cheapest prop i can find is $55. That's not bad at all but I hate to buy it if I don't need it. Thanks again.

 

[Crosbyman]

if your prop has a rubber hub (Sleeve) it is easy to see .
it surrounds the center core.
not sure if your prop comes with a rubber hub. some come with break away drive pins on the prop shfat in case you hit something
some small props come with break away replaceable plastic inserts .

is this an old faithful 6hp just installed on a different 14 boat..?. make certain you are not getting cavitation due to air .
if you do have a rubber insert some have been known to "PIN" it by drilling the side of the prop and inserting short "pins" or small screws 120 degrees apart


see pict. in KBAIT post

Hub repair

Hey guy's,I'm wondering if anyone has tried or has fixed a spin hub ? I'd like to try to repair mine off my 25 hp Johnson,if so what types of adhesive would one use,and the prep steps,I can get a new propeller for around 80$ but thought I'd give this a whirl

forums.iboats.com

 

[racerone]

It has a rubber hub !----And yes it can slip.----Sorry , I can not get my hands on your motor or hear your motor to do the simple diagnosis

 

[F_R]

Hingeman, that o-ring you see in the parts book is not on the prop. It goes around the gearcase head & bearing assy.

The rubber hub is not visible on the 6h prop. All you will see is the bronze part of the hub. The rubber cushion is between the bronze and the propeller body itself. See attached picture and you will understand. (Note: the picture is for a 35hp. Same thing but different.) The rubber cushion is bonded to the bronze part and then the whole thing is pressed/spun into the propeller. Not normally a DIY job. If the bonding is torn loose from the bronze, it will slip under load.

It is a simple job to test the hub for slippage. Make a mark on the prop nut, and another mark on the propeller itself, aligned with the first mark. Run the motor till suspected slippage occurs. Then stop the motor and check your marks. If they no longer are aligned, the hub slipped----or the drive pin is busted.

You mentioned tree tops in the lake. If any weeds or sticks, etc get snagged on the prop or lower unit, it will cause cavitation (air bubbles around the prop blades)

 

[saltchuckmatt]

I'm not aware of any "prop nut".... should be a shear pin and a cotter pin.

I'm betting internal gear assembly issue or two old fat guys in an overloaded 14 ft boat shooting birds might have to do something with it!

Might be time for a bigger motor.

 

[racerone]

That 6 hp has a prop nut !!

 

[saltchuckmatt]

More of a cap than a nut but whatever.

 

[racerone]

The end of the propshaft is threaded.----It is called a "prop nut " in the parts book.-----It screws onto the propshaft.

 

[hingeman]

The end of the propshaft is threaded.----It is called a "prop nut " in the parts book.-----It screws onto the propshaft.

The end of the propshaft is threaded.----It is called a "prop nut " in the parts book.-----It screws onto the propshaft.

That makes more sense now. Sometimes the exploded diagram gets a bit confusing when they try and fit everything on the page. As always, a wealth of information on here from a bunch of different people and each and every one is appreciated! Scott