Engine howls.

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Andis

Cadet
Joined
May 30, 2012
Messages
8
Hi.For first,sorry for my poor English.But please try to understand me and assist.I have boat Yamarin and outboard Yamaha F50 AET.
The problem is when I start to accelerate,sometimes engine howls.It sounds like in idle with full acceleration or without water?.
I will try to explain more.Ourtboard is working very well when I start to drive and drive slow.When I accelerate more to go faster,at one moment engine howls very loud.And I have to
It is always when we are 2-3 people in boat but rarely when I boating alone.Trim in the lowest position.
 
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robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Engine howls.

Sounds like you may have a "spun prop", meaning that the black rubber bushing in the prop hub has failed and is slipping some under load, like a slipping clutch on a car. You may need a new prop, or have that one repaired....for a 50HP motor, a new prop might be your best option. Good Luck!
 
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Andis

Cadet
Joined
May 30, 2012
Messages
8
Re: Engine howls.

robert graham said:
Sounds like you may have a "spun prop", meaning that the black rubber bushing in the prop hub has failed and is slipping some under load, like a slipping clutch on a car. You may need a new prop, or have that one repaired....for a 50HP motor, a new prop might be your best option. Good Luck!
Click to expand...

Thank you Robert.But I cannot understand why you reccomend new propeller if you write that black rubber bushing has failed.I understand propeller is aluminium wings outside?Or prop is set of details inside and outside engine?
Please explain.
 
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robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Engine howls.

The props are made of 2 pieces, the outside with the blades and the inside hub with the splines that slide onto your prop shaft. The 2 pieces are joined together with a black rubber bushing to provide some flexibility. That black rubber bushing can fail and cause the engine to spin and rev up, like with a car's clutch slipping. A prop shop can replace the rubber bushing, but you can buy a new prop for your motor fairly easily. Good Luck!
 
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Andis

Cadet
Joined
May 30, 2012
Messages
8
Re: Engine howls.

robert graham said:
The props are made of 2 pieces, the outside with the blades and the inside hub with the splines that slide onto your prop shaft. The 2 pieces are joined together with a black rubber bushing to provide some flexibility. That black rubber bushing can fail and cause the engine to spin and rev up, like with a car's clutch slipping. A prop shop can replace the rubber bushing, but you can buy a new prop for your motor fairly easily. Good Luck!
Click to expand...

Robert,may be think that my questions are stupid but in my country boating is not popular,there is diificult to get professional recommendations.
Regarding new prop,i understand I have to buy other kind or size of prop?How I can know what kind of propeller I need for my outboard?
 
C

CoffeeHound

Petty Officer 1st Class
Joined
Jan 20, 2012
Messages
210
Re: Engine howls.

Friend == I understand your problem and will try to help you .
Your motor wings are welded to a large pipe --- yes ?
Inside that large pipe is a rubber pipe . --- yes ?
Inside the rubber pipe is a brass pipe with teeth ---yes ?
Inside the brass pipe is your motor drive shaft .
We say your rubber pipe is maybe bad and need fixed !!
Pray this will help you --- be pleased to reply back .
 
Triton II

Triton II

Commander
Joined
Nov 23, 2004
Messages
2,479
Re: Engine howls.

Andis, it could be as simple as trimming the motor to the fully down position and see if the engine still howls when you use the throttle hard. If it does, then you probably have a "spun prop" as explained above. If the boat accelerates and there is no howl then it is simply a trim position issue. A photo of the motor on the transom would help us help you as it could also be that the motor is set too high on the transom. Let us know. Good luck,

TII
 
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robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Engine howls.

Andis said:
Robert,may be think that my questions are stupid but in my country boating is not popular,there is diificult to get professional recommendations.
Regarding new prop,i understand I have to buy other kind or size of prop?How I can know what kind of propeller I need for my outboard?
Click to expand...
Remove the prop and check for numbers stamped on front of prop. Numbers like: 12-1/2 X 14, or similar, indicating the pitch and diameter of prop, so you may order a new one, just like yours. Props can be ordered on-line and delivered in a few days. Good Luck!
 
A

Andis

Cadet
Joined
May 30, 2012
Messages
8
Re: Engine howls.

Thank you for all sugestions.tomorrow mechanik will check this problem.I will inform you about results.
 
A

Andis

Cadet
Joined
May 30, 2012
Messages
8
Re: Engine howls.

Motor was on lowest position when I started to accelerate.
 
A

Andis

Cadet
Joined
May 30, 2012
Messages
8
Re: Engine howls.

Triton II said:
Andis, it could be as simple as trimming the motor to the fully down position and see if the engine still howls when you use the throttle hard. If it does, then you probably have a "spun prop" as explained above. If the boat accelerates and there is no howl then it is simply a trim position issue. A photo of the motor on the transom would help us help you as it could also be that the motor is set too high on the transom. Let us know. Good luck,

TII
Click to expand...
Motor was on lowest position.
 
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robaloroger

Petty Officer 2nd Class
Joined
Feb 16, 2010
Messages
123
Re: Engine howls.

Is it possible the motor is not long enough? Maybe you have the wrong shaft length. Maybe you have a 25" transom with a 20" motor..
 
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Andis

Cadet
Joined
May 30, 2012
Messages
8
Re: Engine howls.

Thank you to all but specially to Robert.He was right.I changed propeller and all is O.K.
 
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