Please help!!!

[Skint back kennels]

I have a 1976 Evinrude 25 extra long shaft on a 1985 sea nymph 15 ft bass attacker. I have owned the boat for about 5 years. From the day I got it it seems to slip out of gear at full throttle. Some times worse than others and sometimes not at all. One time it wouldn’t go at all except in reverse. I have replaced props before and they work for a little while then it happens again. I took it out the other day and it ran fine for about half an hour then it started to slip. It started doing it at WOT. I drove it around for an hour at 3/4 throttle with no problem but soon as I started giving it more gas it would slip. Then after a while it started slipping at anything above half throttle. I have read it could be my clutchdog but would that come and go like that. I am at the end of my rope with this motor but it runs too good for me to sell it and buy someone else’s problem

 

[racerone]

There are no special tools required to work on the lower unit.-----Take it apart for a look see at the clutch dog and forward gear.

 

[F_R]

Is it actually coming out of gear or jumping like you hit something? OR--is it slipping like spinning your wheels on ice?

If the second scenario, it probably is a slipping propeller hub. Clutch dogs are a lot more violent with jumping and banging.

Weeds on the lower unit will also make it "slip" but that's cavitation (ventilation---air around the prop).

 

[Skint back kennels]

Is it actually coming out of gear or jumping like you hit something? OR--is it slipping like spinning your wheels on ice?

If the second scenario, it probably is a slipping propeller hub. Clutch dogs are a lot more violent with jumping and banging.

Weeds on the lower unit will also make it "slip" but that's cavitation (ventilation---air around the prop).

Its like it just all of a sudden starts revving and not pulling anymore. No violent banging or jerking. I back off the throttle and go again and it will go until it slips again

 

[Silvertip]

Spun hub in the prop. Clutch dog issues usually make a chatter/snap/jump situation.

 

[oldboat1]

That plate above the prop --- Is it below the bottom of the hull? (i.e., Where is it in relation to the bottom of the hull/keel?)

 

[Skint back kennels]

That plate above the prop --- Is it below the bottom of the hull? (i.e., Where is it in relation to the bottom of the hull/keel?)

It’s about an inch or two below the hull. At the top pin that has the motor the highest. I took the skeg off and am looking at the gears right now

 

[oldboat1]

May misunderstand you, but sounds like you are talking about the trim(?) Try trimming it down toward the transom -- plate at about the same angle as the bottom of the boat.

 

[Skint back kennels]

May misunderstand you, but sounds like you are talking about the trim(?) Try trimming it down toward the transom -- plate at about the same angle as the bottom of the boat.

Their is no trim on the boat except for the 4 pin holes. It’s in the top pin farthest away from the transom. That’s where I get my best performance in the water. If I put it in the bottom pin (closest to the transom) the motor is almost sitting under the boat. Forgive my vagueness I’m not a boat guy by no means

 

[oldboat1]

Good luck with the performance issue. Don't think it's mechanical.

 

[Skint back kennels]

Good luck with the performance issue. Don't think it's mechanical.

So what your saying is there nothing wrong with the motor. I went rockfishing two years ago and it got to a point where it wouldn’t even go in forward. It would only pull in reverse

 

[oldboat1]

When you get it back together, try trimming it down. If it won't go into gear ("go in forward"), that would be mechanical, possibly adjustment or an assembly issue.

 

[Skint back kennels]

When you get it back together, try trimming it down. If it won't go into gear ("go in forward"), that would be mechanical, possibly adjustment or an assembly issue.

I’ve already took it apart and turned the clutch dog around. It will go into gear every time. It just slips under a load. Mainly WOT. I will take it out on the water tomorrow and update

 

[oldboat1]

Assuming it works better under load, you may find that the boat is slower than you like or expect -- motor a bit too deep (too far below the bottom of the hull). If that turns out to be the case, a solution would be to raise the motor vertically -- use a one by two or similar on top of the transom to raise the motor. Hope you get it handled.

 

[merkdawg0084]

Sounds like it’s coming out of the water, trim it down a little. Pull the pin out and move it closer towards boat..

 

[Skint back kennels]

Assuming it works better under load, you may find that the boat is slower than you like or expect -- motor a bit too deep (too far below the bottom of the hull). If that turns out to be the case, a solution would be to raise the motor vertically -- use a one by two or similar on top of the transom to raise the motor. Hope you get it handled.

UPDATE:

I took my boat out today. Bare with me and read carefully please because I am going to describe what happened EXACTLY. I take off from the boat ramp ease on to the throttle. Within about 20 seconds I’m at WOT and cruising. I went all the way across the lake which is about 4 miles AT FULL THROTTLE WITHOUT LETTING OUT and turned around and came back. When I got back to the ramp I let out of it I was about 100 foot from the no wake buoy so I gave it some gas and it slipped. Went through the no wake zone and eased into the throttle. Went half throttle for a few minutes when I went to throw the coals to it it slips. Turned around hit the throttle at full slips right away. Then I went and rode for about 10 min at half throttle with no issue. Go to WOT and you know what it did. When I say slips the engine revs and it stops pulling until I let out. From what I gathered I could have drove for hours from the beginning cause it ran fine at WOT but when I let out that first time the problem arose again. PLEASE HELP I am stumped

 

[F_R]

Test the prop already!!!! Make a mark on the prop nut (or just use the cotter pin as a mark). Then make a mark on the prop, aligned with the first one. Now run the motor till the suspected slippage occurs. Stop and look at the marks. If they no longer align, the hub slipped. If they do align, repeat the test--there is a rare chance it stopped slipping in the same position.

 

[Skint back kennels]

Test the prop already!!!! Make a mark on the prop nut (or just use the cotter pin as a mark). Then make a mark on the prop, aligned with the first one. Now run the motor till the suspected slippage occurs. Stop and look at the marks. If they no longer align, the hub slipped. If they do align, repeat the test--there is a rare chance it stopped slipping in the same position.

UPDATE:


I’m going to say something my wife never says. “You were right” I put a new prop on the boat and the problem is gone. Crazy how it only did it at wide open throttle. Thank you to everybody who chimed in and tried to help

 

[merkdawg0084]

just curious how does a hub slip? of course i have little motors with shear pins so i wouldn't ever experience a spun hub. I was just looking for more knowledge. thx

 

[F_R]

just curious how does a hub slip? of course i have little motors with shear pins so i wouldn't ever experience a spun hub. I was just looking for more knowledge. thx

A typical prop has the prop itself, and a bronze hub that goes on the shaft. Between the two is a rubber cushion, the purpose of which is to protect the drive train when shifting or hitting underwater objects. The rubber is bonded to the bronze hub. If the bonding fails, it will slip when power is applied.