4.3 volvo Penta Engine Noise?!

[poolboyy72]

I have an engine noise I cannot diagnose. I have a 2005 Reinell with a 4.3GL and volvo sx outdrive. The boat has 150 hours and runs great. However, when the boat is idling, there is a loud whirling knocking sound coming from the engine compartment. When I put the boat in gear, either forward or reverse, noise goes away. I have checked gimbal bearing and u-joints and they look and feel good. Anyone have an idea of what this noise could be?

Thanks...

 

[Lyle29464]

Re: 4.3 volvo Penta Engine Noise?!

Did you try it with the drive off?

 

[poolboyy72]

Re: 4.3 volvo Penta Engine Noise?!

I may try that. When running the boat with water-muffs in my driveway, the noise is not that noticeable. But when the boat is in the water, it sounds horrendous. I have been battling this problem for three years...

 

[cr2k]

Re: 4.3 volvo Penta Engine Noise?!

A few possibilities;

Gimbal bearing
U-Joints
Engine Coupler worn
Input bearing in drive upper
broken balance shaft