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Old 25 July 2014, 17:56   #1
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Country: UK - N Ireland
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Mariner 25hp two stroke, loss of power.

Good evening gents, and ladies, I have a mariner 25hp two stroke, I had it in the water for the first time this year and have had a problem when under load.

the engine fired up almost straight away from last year, tell tale was pumping water fine and the engine ran great at low speed, but as soon as I opened the throttle the power just wasn't there, the engine revved fine but didn't pick up speed.

Once the boat was just out of the water I ran the engine at full power for a few seconds to see if the forward gear was disconnecting but it ran at full pelt with no problems, can anyone offer advice?
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Old 25 July 2014, 20:26   #2
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Spun prop hub? Too much pitch?

Has it ever run correctly? (if so, you can skip the second one)

jky
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Old 26 July 2014, 05:30   #3
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How can I check if the prop hub is spun? Thanks for your help
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Old 26 July 2014, 05:37   #4
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Put a mark accross the out and inner hubs of the propeller. Run the engine under load i.e. in the water and if the mark no longer lines up you have a knackered hub.

Steel Developments will re hub it for you, cost about 20 last time I had it done.
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Old 26 July 2014, 06:41   #5
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Quote:
Originally Posted by Landlockedpirate View Post
Put a mark accross the out and inner hubs of the propeller. Run the engine under load i.e. in the water and if the mark no longer lines up you have a knackered hub.

Steel Developments will re hub it for you, cost about 20 last time I had it done.
Thanks for your help mate, I'll try that as soon as I can get it back in the water.
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Old 26 July 2014, 11:46   #6
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You could just try putting it in gear with the engine off and spinning the prop by hand the correct direction. Worst case it turns the engine over.
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Old 26 July 2014, 16:14   #7
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You could just try putting it in gear with the engine off and spinning the prop by hand the correct direction. Worst case it turns the engine over.
I can do that no worries, should it spin freely rather than turn the engine over? Cheers.
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Old 26 July 2014, 17:29   #8
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No it should not spin freely in gear. If you turn it by hand and the motor turns over, then the hub "could" only be slipping under a heavy load. In other words it doesn't mean the hub is in good shape.
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