loss of thrust

I was running along and my 40hp Evinrude revved up and now has no thrust...doesn't seem to be engaging...didn't hit anything and have not had any prior problems...I have verified the shifter is moving, but don't know what else to check for...any suggestions are appreciated in advance

Re: loss of thrust

Possibly the shear pin?

Re: loss of thrust

Maybe a spun prop?

Re: loss of thrust

"loss of thrust"
You should really reword the title of your thread, if leaves alot lo the imagination
LOL

Re: loss of thrust

I would suggest removing the shift cable and then shift it manually to see if it engages better. If it does then you'll have to adjust the cable if not then when was the last time you removed the gear case? Perhaps you need to adjust the shift rod. Let us know what you find or don't find. What year is your Evinrude? Best of luck. Rick.

Re: loss of thrust

If the motor is revving up as it should but the boat is going nowhere, you either have a sheared drive pin or a spun hub on the prop. Remove the prop and check the drive pin. If that's ok, then draw a line across the prop hub with a waterproof marker and run the boat until it does the same thing. Now check the line and see if it's moved. If it has, you have a spun hub.

Re: loss of thrust

54fleetwin said:

"loss of thrust"
You should really reword the title of your thread, if leaves alot lo the imagination
LOL

Click to expand...

The next Elton John song.

I'm with the hub, pin group.

Re: loss of thrust

If you can get a slow trolling speed but it just revs up and you go nowhere when you throttle it up to higher levels, then most likely your prop is spun.

Re: loss of thrust

Rick. said:

I would suggest removing the shift cable and then shift it manually to see if it engages better. If it does then you'll have to adjust the cable if not then when was the last time you removed the gear case? Perhaps you need to adjust the shift rod. Let us know what you find or don't find. What year is your Evinrude? Best of luck. Rick.

Click to expand...

where is this here sheered pin or spun hub...when I take the prop off I get to a seal within the prob shaft housing...everything else looks good...should the prop shaft spin if in gear...???...don't think so, so the problem is inside the prop shaft housing or on up to the drive shaft...???

Re: loss of thrust

Not when in gear, well it will by the rotation of the powerhead, but not free spin while in gear like it does in neutral.

Re: loss of thrust

where is this here sheered pin or spun hub...when I take the prop off I get to a seal within the prob shaft housing...everything else looks good...should the prop shaft spin if in gear...???...don't think so, so the problem is inside the prop shaft housing or on up to the drive shaft...when in gear and turning the prop shaft by hand, I hear a thunk in the middle of the prop shaft housing but nothing happens except a little resistance...plus how can you insert a picture on these posts...???

Re: loss of thrust

First of all what year is the 40, 2000 or 1962, big difference, it may not even have a shear pin/drive pin?

Re: loss of thrust

this is a 1988 40 hp Evinrude with electric start and remote steering...tilt and trin on outside of motor mounts...

Re: loss of thrust

So it won't have a drive pin then, it's a splined shaft and a through prop exhaust hub. When you put it in forward you should be able to free spin it in one direction, when you go in the opposite direction it should lock up inside the gearcase, if you continue to apply pressure the flywheel should start to turn. As OptsyEagle stated, a spun hub can troll, it's only evident when going over quarter/half throttle, the RPM's will climb higher than what the engine should perform at during regular operation, it's an "overrev" condition. In the center of the through hub exhaust is a splined insert which is surrounded by rubber which is pressed into a hub and then i'm assuming is somehow glued to the metal. When you hit a rock or stump, instead of a shear pin breaking the rubber inside the prop will break away from the prop housing. Once this happens it's known as a "spun hub" as it cannot take the torque of the motor at high speed operation. This is my explaination, if it's wrong someone will correct me but it's my undertanding on how things work. There is a bushing listed for the prop but I'd imagine this has to be installed by a prop shop with a press and all the proper tools.

Re: loss of thrust

and to fix it, I do what...drop the lower unit right above the cavitation plate and then...???

Re: loss of thrust

I don't know this motor, I'd be looking at the shifting components to make sure the shift shaft is still connected and everything is moving before pulling the gearcase apart.

If you remove the prop can you turn the splines in the prop by hand? I suspect the answer will be no.

Re: loss of thrust

the splines inside the prop itself...???

Re: loss of thrust

and whaat does that tell me...???

Re: loss of thrust

when I spin the prop, the prop shaft spins also

Re: loss of thrust

If the splines in the prop can turn by hand the prop is fooked.