johnson 88spl sounds like its slipping? suggestions?!? thank you!!!

[mpd51890]

hello everyone, i have a fiberglass 17ft center console with a johnson 88 spl , the issue i am having sometimes is when im going to plane the boat, sounds like the rpms shot up and the but just dies down like the prop is slipping or something, then i have to back it down put it into neutral and work my way up to plane again, sometimes i have to do it multiple times before it will plane out, the motor runs good from idle and when cruising , just this issue any suggestions , thank you very much!

 

[jakedaawg]

Your prop hub is starting to go. Remove prop, make a mark on inner sleeve and a coresponding mark on the outer sleeve. Run boat till it slips. Remove prop and note location of marks, if they have moved take to a prop shop and have them install new hub.

If they do not move chances are you are cavitating and have an improperly loaded boat, improper trim angle, or improper motor height installation. The cavitation plate should be an inch or so below the bottom of the pad or vee. If it is a tunnel hull or planing pontoon draw an imginary line from below the hulls and see if your plate is an inch or so below this line.

You may also have a trim pin in the bracket that is set to high, try lowering it a notch or two.

 

[mpd51890]

Your prop hub is starting to go. Remove prop, make a mark on inner sleeve and a coresponding mark on the outer sleeve. Run boat till it slips. Remove prop and note location of marks, if they have moved take to a prop shop and have them install new hub.

If they do not move chances are you are cavitating and have an improperly loaded boat, improper trim angle, or improper motor height installation. The cavitation plate should be an inch or so below the bottom of the pad or vee. If it is a tunnel hull or planing pontoon draw an imginary line from below the hulls and see if your plate is an inch or so below this line.

You may also have a trim pin in the bracket that is set to high, try lowering it a notch or two.

it is a deep Vee shape boat, the boat started doing this about two years ago it was my uncles boat he told me about it, it started happening at the end of the season, so i replaced the trim(hydrofoil), still having the same issue, my uncle said he did bring it some where to get the prop checked and said it was fine, but they could be wrong ill do that marking like you said though! the motor might actually be to high, i have to double check that! if the motor is to high up would it cause that?

 

[jakedaawg]

yes.

so i replaced the trim(hydrofoil),

If you mean that you have some fin thingy on the cavitation plate I would try removing it first.

In the clamp that holds the motor to the boat there is a pin that limits the motors ability to go down. Counting from the transom, what number hole is it in?

 

[mpd51890]

id have to check tomorrow, the boat is stored at my uncles, but i also think the motor might be mounted to high also

 

[emdsapmgr]

If the engine is mounted too high, the prop can suck air and ventilate as you describe. It the engine was raised in order to use a stainless prop, then a stock aluminum prop was substituted, that's a reason for ventilation, too.

 

[mpd51890]

Okay yeah well there's a aluminum 14x17 prop I belive that's the oem prop for the motor,

 

[mpd51890]

And the bar is on the last hole for the tilt rod if that's what your talking about there's like 5 different holes u can chose right (so the last hole close's to the bottom of the boat

 

[mpd51890]

bumppppppppp ttt

 

[Fed]

I'd bet money on the prop hub slipping.

 

[mpd51890]

I'd bet money on the prop hub slipping.

Yeah I'm almost leaning towards that also ,

 

[mpd51890]

could the pitch of my prop be causing this>? any one have a good suggestion i have a 14in x 17in prop on there now, its a 17ft center console ...

 

[jakedaawg]

Just check for a spun hub first. Its where you start when diagnosing this issue. A 14x17 souds reasonable.

 

[mpd51890]

Well if it's a bad hub am I better off just getting a new prop? It is a little ding up not to bad, was maybe going to get a different pitch if needed, and is the hub on these prop something I can change myself I am very mechanical incline

 

[Will Bark]

Let the gurus advise on a new prop as to what pitch and so forth but the answer about DIY on the hub; no, it is a job for the prop shop. They have the equipment for that. Good luck

 

[mpd51890]

No Title

 

[mpd51890]

the prop hub , took off the prop today just to take a glance at the hub dosnt look to promising !

 

[jakedaawg]

Make a mark on the inner hub metal edge and a corresponding mark on the outer. Run boat. See if marks are still in the same place. You cant really tell by looking.
Stop worrying about pitch and all that stuff. 1st things 1st. This is a free test except for your time and no way around it.

 

[mpd51890]

Yeah I planed on doing that this weekend mark it and test drive it

 

[mpd51890]

Well I took the prop back off and marked it today and put it back on was on the water for about 6 hours today and no slips at all, I did tighten the prop castle but tighter then it was before could something that stupid of the nut being tight enough do that?