About a month ago while at Lake Mohave, I noticed a very slight burning rubber smell in our boat. The only time I would notice it would be after running at speed when coming back to idle speed. I'd notice the smell for a while, then it would seem to go away. Boat has a 1995 Merc 350 Mag EFI/MP (version with the tunnel ram style intake) and Bravo 1 with Rex Marine cutouts/thru hull exhaust (y-pipe connected to the cutouts). I checked the belts, exhaust hoses etc. and didn't notice anything out of the ordinary, nor could I isolate the source. I'm suspecting the flappers in the exhaust pipes at the transom to be the culprit, but I'm not sure. Water and oil temps were all normal. Exhaust manifolds and elbows didn't appear to get overheated and there was the normal flow of coolant out the pipes. Is this a sign of impending water pump failure, exhaust flapper failure or are the exhaust manifolds on the fringe of coming apart? Boat has 480 or so hours on it and has always had routine fluid and filter changes. Engine still runs like a champ and starts on cue. Any insight or suggestions welcome.
Trash