Prop slipping?

[DaleS]

I've got a '78 15 Hp Evinrude that starts right up, idles and runs great at trolling speed but when I give it throttle, it clunks as if I hit a log or something. I've just put a carburator kit in because I thought it was backfiring. Some time ago, I read a posting in this forum that said the prop may be slipping. I think that post referred to a rubber clutch type thing. Is this part of the prop?<br />Thanks,<br />Dale

 

[angus63]

Re: Prop slipping?

If it clunks, it usually means clutch dog is slipping in the lower unit when a load (acceleration) is applied. Prop slipping will cause you to rev higher while accelerating and then level out when a constant velocity is achieved. If you slowly accelerate and no clunk is felt, I'm pretty sure it's the dog (sorry). When was the lower unit oil last changed? Are you sure the shift lever is fully engaged when you put it in forward? let us know.....<br />Good luck

 

[DaleS]

Re: Prop slipping?

I actually held the shift lever in place to make sure it was staying engaged. I did not notice the rpm increasing at all...just a very noticeable "clunk". It would keep doing this every 5 to 10 seconds at a constant speed, except very slow. I don't have my service manual here with me. Are there special tools required to change the dogs?

 

[angus63]

Re: Prop slipping?

You have many options once you are sure what the problem is. Replace worn parts, rebuild lower end completely, buy a rebuilt lower end, buy a used lower end, etc... Verify what the problem is first. If your not sure what your looking for, have someone who is do it for you. It may be as simple as a shift rod adjustment.