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1987 Mercury 25XD spins out with load

fishingaggie

New member
I have a 1987 Mercury 25xd. It starts and runs great up to about half-throttle. Once you get to half throttle, the engine RPM's will rev and the the motor will stop moving the boat forward, similar to a spun hub. If you drop it back down to idle, it will run perfectly up to about half throttle. It is very repeatable and happens at exactly the same rpm's every time. It has been a real bugger to fix because it runs perfectly in a tank, all the way up to full throttle. It's only an issue under a higher load (when it's pushing the boat). Any ideas would be appreciated!
 
In the parts diagram, it shows as a single part. I tried to get the hub out as you would do with a modern, larger engine and couldn't get the core out. I hope that's the issue!
 
It's a single part as far as the layman is concerned since the hub is pressed in place and not removable without the special equipment to do it. . You can either purchase a new prop with correct pitch or send the prop to General Propeller down here in Florida and they'll rehub it for you. Your local marina usually offers this service to send the prop out and get it back in a week or so.
 
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