Knocking/Rattling Sound When Backing Up

[wepucci]

I recently purchased a 1997 Ski Nautique. When I put it in reverse, it makes a knocking/rattling sound that is unsettling. The boat backs up fine, it's just annoying and I would like to know what it is (and if I can fix it).

Thanks.

[MHayes]

RE: Knocking/Rattling Sound When Backing Up

This is normal, so need to worry about it. Do a search and you'll find several threads on this topic.

[TRBenj]

RE: Knocking/Rattling Sound When Backing Up

I wouldnt call knocking/rattling normal. Could be a bad damper- tough to say with the limited description.

[east tx skier]

RE: Knocking/Rattling Sound When Backing Up

My old MC did this. My CC dealer told me that boats will often develop this symptom with age as a glaze forms on the clutch packing. I've also heard the damper plate to be the culprit.

Not likely with the castle nut, but be sure your prop nut is on there good and tight. I had a nylock nut loosen up on my old boat making the reverse rattle a little worse.

[MHayes]

Re: RE: Knocking/Rattling Sound When Backing Up

I wouldnt call knocking/rattling normal. Could be a bad damper- tough to say with the limited description.

It's according to the extent of knocking/rattling, but yes, this is fairly normal on most all inboards....when putting it in reverse, especially ever so slightly, it does not give you the smooth sensation of going forward.

As SGY once stated in an earlier thread, "Small rattle or knock in reverse is normal on PCM 123:1 gear reduction tranny".

[TRBenj]

RE: Re: RE: Knocking/Rattling Sound When Backing Up

Ive driven a lot of 1.23 boats and I wouldnt say that any of them knock or rattle. Id say putting an inboard into reverse makes a "whirring" noise. A bad damper or other problem would cause a knock or other abnormal noise.

[wepucci]

I don't know that I would classify what I am hearing as a "small knock or rattle". It's pretty pronounced - not constant, but audible for a second or two, then inaudible, then audible for another second or two - etc. I could probably record it into an MP3 file and email it to anyone who was interested.

What exactly are the clutch packing and the damper plate? Are these things that can be repaired by a mechanically-inclined person or does one typically have to have an expert work on them?

Thanks.

[AirTool]

wepucci,

I was going to suggest you post a recording. I would like to hear it. I don't think you have a problem, though. I have a 06 206. It whirls in reverse as many have suggested. It also rattles....like marbles or a drum roll. The pattern is about two seconds of drumming....maybe 10 to 12 pops. Then 4 to 5 seconds without. ...then repeats. I can't tell if it does it under fast reverse.....as the engine is generally louder.

AirTool

[i_am_am]

make sure the engine idle is not down low enough to cause it.

[kentsmith12]

I have a 2000 Pro Air and mine has done it for the last 3 seasons. I've had it checked out and nothing is wrong. I've been told its normal and I've learned to live with it. You can always raise the RPMs a little and it goes away. Functionally, you should be fine.

[slalomdude]

Art, at Secc, told me over the phone, that its normal. Next time his is down at my club, I will get him to listen to my boat. Its doing the exact same thing. For those guys that dont know Art, he has about 40 years experience of CC and inboards.