hmmm. Not the most experienced with these engines, but will try to help. No, there is no type of insulation around the rubber exhaust/water relief hose. Does it look like this engine has been altered in any way? Perhaps someone converted it from short to long shaft? Does the powerhead look original? These engines were very quiet, a little louder when first started cold until the inner exhaust got “wet down”, but still not loud at all.
You have looked at the donut gasket around the midsection, and that is OK. Is there any evidence of an exhaust leak with the engine cover removed? It just seems like an exhaust leak big enough to cause alot of exhaust noise should be evident. I am assuming you are running the engine on a boat in the water, and not on a flushette or in a shallow bucket as well.
Feel free to post pictures or links to pictures if they won’t fit here…
No insulation around the outside of that hose or inside it either….
