GAR9
New Member
I have a 29 ft sailing yacht with a volvo 2001 engine connected through a volvo gearbox to a conventional shaft drive. I believe it is the boat's original engine which makes it of 1987 vintage. It has been reasonably well maintained throughout its life as far as I know and although not heavily used, it will have been used steadily throughout its 25 years of life. It has started to exhibit a strange characteristic - after running for several mins under moderate load or fast idle, it starts to make a strange whooshing or hissing sound. This goes off for about a second every few seconds then increases in frequency and duration over time; more quickly if the load or idle speed is increased. At high speed it is almost continuous and quite loud - sounds like high pressure air or gas escaping inside the engine somewhere. There is no external sign of any problem - no gas, oil or water leaking - it all seems to be happening inside the engine - possibly towards the forward right hand side of the engine. The alternator belt is correctly tensioned, there is plenty of cooling water coming through the system and the engine seems to be developing its normal power. On returning to slow idle the noise stops. Any suggestions?
GAR, Menorca, Spain
GAR, Menorca, Spain