Starboard Engine doesnt sound right

buggyjdav

2004 342,with Merc 350 Horizons. Boat ran fine last weekend, belt was squeeling quite a bit but otherwise ran well. Started it up today and starboard engine doesn't sound right, there is a clunking sound is the best way I can describe it. Checked oil, looks fine. Any other things I can check before calling a mechanic?

buggyjdav

What does bad fuel sound like? Just realized I never put additive in starboard tank... Both engines are knocking but starboard is worse so my theory may make sense

buggyjdav

Thanks guys. One more thing, the noise doesn't happen right away, takes 30 secs to a minute for it to happen. One more thing, it was only happenning with drives all the way up, lower them even half way and the noise dissapears!?!? Any ideas?

Black_Diamond

A squealing belt means it is slipping. I would check all the belt driven components with the belt off for free spinning. A bad bearing will do that. Idler pulleys especially. 

aero3113

I'm pretty sure you shouldn't run the engines with the drives all the way up, you are stressing the universal joints. It could also be a bad gimbal bearing.

MarkB

buggyjdav said:

Thanks guys. One more thing, the noise doesn't happen right away, takes 30 secs to a minute for it to happen. One more thing, it was only happenning with drives all the way up, lower them even half way and the noise dissapears!?!? Any ideas?

What do you mean by drives all the way up?  Even if you are tilting them up to the max operating level, you could be cavitating the drives. But you would have noticed a big change in boat performance if you did that.