what is this noise?

ryan04

Petty Officer 1st Class
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Jan 26, 2005
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212
hey guys, I just picked up a 1995 Reinell RXL Cuddy with a 5.7 Mercruiser. Starts no problem idles so smooth and quiet. I put it in the water the other day for the first time and was cruising at around 20 MPH, and thought I'd pick up the speed a bit. At this point the engine sounds gorgeous, when I speed up I hear this strange noise. It's not bearing or u-joint noise, it's in the engine for sure. It's like a rattling ting noise. I had something similar with my last boat which turned out just to be a sticky lifter. What other stuff can cause noise like this? Timing chain? Needle bearing on piston??
 

Don S

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Aug 31, 2004
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62,321
Re: what is this noise?

Hard to troubleshoot sounds on a forum, but it could be pre ignition (Pinging) the sound of your pistons melting down.
Is the timing set correctly? Does the advance work to specs? Do you have Thunderbolt V or Thunderbolt IV ignition? Does it have a knock sensor? Does it work?
 

Hansolo99

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Jun 27, 2009
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Re: what is this noise?

Does it only do it at a certain RPM? Does it do that when it is not in gear and you give it throttle??
 

ryan04

Petty Officer 1st Class
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Jan 26, 2005
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212
Re: what is this noise?

When it idles it's so quiet and so nice, only in the higher RPM while under way does it start to make noise. It's got a Thunderbolt IV ignition on it.
 
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