1960's Johnson 40HP..gear problem???

[joe0523]

I am new to boating and just bought a 1960's 15' Starcraft w/ 40hp Johnson outboard. Before putting it in water I changed lower unit oil. Put it in water for first time and it ran well for about 5 minutes, I slowed down then went to speed back up and the motor accelerated but the boat didnt. It will only let me go about 1/2 throttle and then it seems like its in neutral, but the shifting lever is still at forward. Any ideas on what my problem is and how to fix it. Remember, I am new to boating so please use generic terms, Thanks!

 

[OBJ]

Re: 1960's Johnson 40HP..gear problem???

Hi Joe and welcome to iboats forums..<br /><br />What you may be experiencing is a spun hub.<br /><br />The prop has a rubber hub that will let the outter portion or aluminum portion spin if an underwater object is encounter. (like smashing a log under water with the prop.) This hubs will get "tired" and spin on their own. Classic tell tale, engine rpms go up but speed of boat does nothing.<br /><br />This usually happens at a certain throttle setting like you are experiencing.<br /><br />Pull the prop and look at the end closest to the gear housing. If you see what looks like little beads of rubber, then most likely it has spun.<br /><br />Or....just to test the therory, (dang I'm loaded tonight) draw a line fron the rubber hub out to the aluminum part. This will be your match line. When the engine does the high rev again, check the match line. If it moves, the hub has spun.<br /><br />Keep us posted....thanks!

 

[joe0523]

Re: 1960's Johnson 40HP..gear problem???

Thanks for the quick response Jim. I will test the theory, if you are right what do I do to fix it. Is this a costly repair??

 

[foxjohnc03]

Re: 1960's Johnson 40HP..gear problem???

Not really, costs $30 to $50 to have a new hub installed.

 

[OBJ]

Re: 1960's Johnson 40HP..gear problem???

Yep....what John C. said.

 

[joe0523]

Re: 1960's Johnson 40HP..gear problem???

Thanks for all the help. I called a local repair shop and he said I need a new prop, about $80. Does that sound right??

 

[joe0523]

Re: 1960's Johnson 40HP..gear problem???

^

 

[Lark40]

Re: 1960's Johnson 40HP..gear problem???

His engine has a shear pin which severs if he hits an underwater object. There is no rubber hub component. The prop is press-fit to the hub....

 

[KT64TM]

Re: 1960's Johnson 40HP..gear problem???

any good prop shop can press a new hub into a prop, you dont need a new prop unless the blades are bent/chewed. i had a '64 prop rehubbed for 38 bux in Oklahoma City. you have a brass hub in an aluminum prop.