What's that noise?

[diskgolpher]

Bought a used 20' Cat with two 75 Merc's this summer. (My first boat.) The starboard motor this past weekend started making a rattling noise (coming from the inside - there's nothing obviously loose). the sound is similar to when your car has valve ticking or when it's low on oil. It is a two stroke motor. Anyone have any suggestions as to what this might be?

Also, any recommendations for good outboard mechanics in the NoVa area?

Thanks.

[Tom Powers]

Could be timing. I would, change the plugs and take it to a reputable shop and ask them to set the carbs and timing. To me this is part of my regular spring maintenance.

[eroller]

The last time I heard that noise it turned out to be a cracked head. I hope that's not your case but I would agree with the earlier post and have it checked.

[katman2860]

When a 2-stroke starts to make that noise it is ussually a bearing on the crank getting ready to let go,don't run it anymore till you get a mechanic to check out. When it lets go you will be replacing the entire block.

[WildeOne]

Agree and could also be a rod bearing.

[diskgolpher]

Thanks for the advice everyone. I didn't think it was a "good" sound that I could ignore and really appreciate your feedback. Better to tend to it now while it's just a noise.

[home cookin']

I hope it turns out OK. I have also been told on Yamaha's that the fuel pump will rattle that way, as well as a loose control cable (hits a vibration at a certain speed).

Let us know what a mechanic finds out, and what would he do to resolve.

[diskgolpher]

Well, thankfully what I got was (what I consider to be) good news! Compression check was good.
The props on my boat were mismatched (15 degree pitch on the starboard motor, 17 degree on the port side). So when I put the throttle forward and maintained synchronized rpm's, the port motor was forcing the starboard engine to over-rotate. An exagerated version of driving with one motor off but in gear and it having the water flow force the prop to spin (and everything else in line with it).
Instead of paying for what I expected to be other engine work, I'm taking this opportunity as a win and biting the bullet by having them both replaced with stainless props.

Thanks for the input everyone.

[Capt Kid]

So therefore your clutch dog was dragging(clicking). Might wanna have it checked. As i belive honda was having problems with thier clutch dogs doing the same thing during rapid deacceleration and eating up the teeth on the 'dogs.