Muffler noise

[Joew2604]

35 ft carver with two 350 mercruisers.. Lot of rumbling noise which for a while thought it was the transmission. Found out it seems to be coming from the barrel like black muffler. Only when slow idle, move to 1200rpm and its gone. Does this sound feasable? Can something break inside the muffler to cause this? Change the muufler? Big. job? Anyone done this? Any info or advise appreciated. Thanks all.

 

[DavidM]

Probably a combination of unknowable acoustic effects and more water being available at higher rpms to help flood the muffler and dampen noise. Might check R/W impellers to make sure ok. The muffler does have baffles inside that if broken might cause the noise, but should be well glassed in place so I wouldn't suspect them.



David