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…

1 user thanked author for this post.

Peter Stockless

A lot of noise comes back out the carb throat that you will hear with the cover off or the access door open, as there is no muffler on the carb intake like the 1957-58  35s had.

I had a 1958  35 HP (not the super quiet one) get really noisy (like a straight pipe) when the exhaust housing cracked just below the water outlet and twisted slightly, opening up a crack about 1/4 inch wide, but you would have found that when you took off the exhaust housing cover.

Let us know what you find.  I have several 1960s Super Quiet 40s, and none are very noisy.

Dave

So, the extension housing fits “loosely” onto the exhaust housing?  What does that mean?  Seems like a great place for an exhaust leak.  You need to figure out why the extension fits “loosely”, that can lead to other problems down the road…  Post pictures/video if that will help.

1 user thanked author for this post.

Peter Stockless