1995 mercruiser 3.0 rattling noise

[olddogmike]

Had my sea-pro 210 wa out today, when I opened the throttle above 3000 rpm I noticed a rattling noise coming from the engine. If I slowed down below 3000 it went away.This has never happened before. With the shift in neutral position I can run it up to 4000 and no rattling. Any ideas as to what is the cause of this? Doesn't seem to effect the engine proformance. This is a 1995 mercruiser 3.0 lx with Alpha 1 outdrive. Not the fastest boat, the manufacturer sure underpowered the 210 Sea-pro when they put that inline 4 in it. Thanks for any feedback you can give me.

 

[Trent]

Re: 1995 mercruiser 3.0 rattling noise

Sounds like your hearing the exhaust shutter. The 3.0 can get a little noisy at certain RPM's.

 

[olddogmike]

Re: 1995 mercruiser 3.0 rattling noise

Trent, thanks for the reply. I should add that the boat was carrying more weight in the stern then normal. The noise was sporatic and did not have any sort of rhythm to it. I was worried that maybe one of the rod bearings was giving it up. But when there was no load on the engine (neutral) the noise went away. Would added weight in the vessel cause the exhaust shutter to become noisier? Thanks for the help.

 

[Northern Eclipse]

Re: 1995 mercruiser 3.0 rattling noise

The rattling noise could also be the the timing gear on the camshaft, they tend to wear since they are a nylon gear,that gear will make noise under load that will make you think that a rod is knocking,or a lifter is stuck,you will need to listen carefully if the gear is making the noise, it will travel along the entire camshaft, and appear as some sort of valve train noise.