Borg Warner makes a "klonk" sound when it goes in to reverse.

Jacob Vetter said:

Well, i found out that if i push the gear into forward and to neutral and then to forward again there is no problem, the same goes for reverse, but the first time it goes from neutral to either forward or reverse it makes a big klonk sound. The blades of an autoprop does not have a stop, they can turn 360 degree endlessly..

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Jeff F said:

I just had a look at the Autoprop web site and they say the blades turn through 180 degrees. Autoprop - Bruntons Propellers

Again, not specific to Brunton, but in my experience well used feathering props can wear and get sloppy. Hard to tell from your description whether yours is operating normally or not.

It doesn't sound like a gearbox issue to me. I'd have someone qualified inspect the prop on the next haul.

I'm not sure whether you've visited Cruiser Forum, but there are many experienced voices there with hands on experience with that prop.

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Bmarler said:

It makes perfect sense that the clunk doesn’t happen when going fwd-neut-fwd, or rev-neut-rev. The blades have already shifted to their stops. When you change direction they need to rotate to the new position and when they hit the stops it clunks. The higher the idle speed the louder the clunk will be.

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Bmarler said:

I thought the blades travel 180 degrees. That would lead me to believe there is a physical stop at the end of the travel.
Are you certain they rotate 360?

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rslifkin said:

I'd expect the clunk is coming from either the reduction unit on the trans or the damper plate when it encounters a sudden change in load while the blades flip to the correct position. A single clunk on shifting at idle power is unlikely to be harmful, just annoying.

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Jacob Vetter said:

Yeah I think your right, but it sure sounds bad!

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Jacob Vetter said:

Hi,
I have a problem with my Borg Warner gearbox. It makes a big noise "klonk" sound when i put it in reverse. The engine is a Ford Lehman 2725E.
I have changed the damper plate, changed the gear oil, but it does not help. No problem when i go in forward.
If anybody have a solution to this problem i would much appreciate to here from you
My ship is not a Trawler, but a 1984 Nauticat motorsailer 40 ft.

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AquilaCat said:

Check your shaft connection to your transmission. If you can easily twist it, that is your source.

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