33 hp 1968

[jbabcock]

Not sure whats going on here replaced head and water jacket gasket the other day took motor out ran like a dream never had it run so good then took it out today runs great at half throttle then when going full out motor revs high almsot like prop is covered in weeds gets that low deep hollow sound to it and looses all thrust go back down to half throttle motor runs fine wondering if this is a bad base gasket or if there is something going not so good in my bottom end changed the oil and checked the shear pin today all looked fine.... any ideas ????

 

[TrueNorthist]

Re: 33 hp 1968

Sounds like it's cavitating. Did you raise the trim angle? (Bow up) My old Crestliner Mustang used to cavitate badly if I raised the bow too much.

 

[Daviet]

Re: 33 hp 1968

Engine revs up, boat slows down. You checked the drive pin, but did you check the hub in the prop to see if it was spun?

 

[jbabcock]

Re: 33 hp 1968

not sure if you can spin that prop the shear pin goes straight threw it however i did just take it off and noticed there is a channel for like a keyway in the drive spindle and prop and that steel key isnt there?

 

[tx1961whaler]

Re: 33 hp 1968

There is only the drive pin there, with the prop nut and cotter pin.
A spun prop is where the rubber hub in between the inner hub and outer prop no longer holds and the prop "spins" on the inner hub at high torque. If you mark a line with permanent marker across the back of the prop you can tell if it slips after running it.

 

[jbabcock]

Re: 33 hp 1968

Thank you that was very informative i had no idea there was a rubber seal in the middle i always though it was one solid brass pressed in fitting its a fairly new prop onle 3 years old but it has met a few stones and bottom a couple times so i will try one of my spares tommorrow thank you again for that info.

 

[Daviet]

Re: 33 hp 1968

Let us know how it turns out.

 

[samo_ott]

Re: 33 hp 1968

Meeting a few stones will make a 3 day old prop spin!

 

[jbabcock]

Re: 33 hp 1968

Yup thats what it was just a bad prop put the spare prop on and moter worked fine kinda a bumber that a prop thats 20 years old outlived a prop thats 3 years old but thems the breaks.

 

[lindy46]

Re: 33 hp 1968

Prop can be re-hubbed for about $40.