mjb

I just put new engines in my top gun with offshore mounts. I reused my old outdrives because they were working well when I took the old engines out. New engines run great but there is an unusual noise coming from the transom on the port engine. It is irregular(not rythmic like an engine knock)-sounds like a hammer on metal and seems to be coming from the transom area. I put a mechanics stethescope on the transom and the bell housing and can't really pick it up. It seems to be worse at idle with no load. I think it is the u joint?? Either because it is just getting old or maybe because there is an alignment issue.
Any thoughts from those in the know.
Thanks- MJB

rdp145

I'm certainly not an expert and you may already have check this but the internal flappers in the thru hull exhaust will make a sound like you describe. I can tell you more if you think that might be possible

mjb

When I first started the engines the sound was from both engines and it was a very light metal to metal sound. I did attribute that to the internal flappers. Over the weekend the sound has become much louder and harsher on the port engine...hammer on metal...you can actually feel it when it is making noise. Now I have ruled out the internal flappers as the cause of that noise.