1976 envirude 40hp slipping under load

[Triangleboater]

Got the engine a few weeks ago not running, did a compression check it passed and it shifted in and out of gear so i took her home. Changed the lower unit oil, put a carb kit and cleaned her out real well and dropped the lower unit and put a new water pump kit in. (there were things growing and hatching in there so obviously hadn't been run in years. Well I got her running real nice in the barrel. Pumped water really well and shifted into forward and reverse. So onto the sea trial.

Took her out yesterday and she was performing good for the first five minutes or so then would start slipping a reving up while in gear. I would lower rev's and it would do ok then slowly raise the throttle and same thing. It felt like the prop was slipping. But, it took the prop off and it doesn't look like it has the rubber like the more modern props and motors. The shear pin on the prop was good to go.

Could it be I didn't hook the linkage up correctly and it is poping into neutral? I did have trouble getting the shift linkage hooked back up through that little plate.

Anyways, any advice would be helpful!
Thanks!
​John

 

[bonz_d]

Don't believe it's your gearcase. Look very closely at that prop. Look very closley at how many different numbers are stamped into it. If there are many then that prop has been worked over many times and is most likely not the same or correct diameter. Had one like that once. It would blow out at about 1/3 throttle. Next mark a line on the prop and the prop nut and then run it. That will tell you if the hub has been spun.

 

[Triangleboater]

Do these old props have hubs? It took it off and couldn't find the hub. Also, it's not held on by a nut. It's held on by a shear pin that's covered by a cone with a pin.

 

[kbait]

It's held onto the propshaft exactly as you describe. Yes, there's a rubber hub bushing pressed in.. between where the drive pin connects (hub) and the metal of the rest of the prop. It's designed to slip if you hit a rock, and over time the rubber degrades and slips under load. New/used prop or have yours re-hubbed at a prop shop.

Good luck!