Small Engines (Lawn Mowers, etc.): noisey Kohler kt17 series II, cub cadet 1811, cub cadet 782

Question
Dear Fred,
I just purchased a Cub Cadet 782 with a Kohler kt17 series II motor that was put in as a replacement motor about 250 hours back.  I bought it sight unseen - big mistake.  The motor is very loud.  It sounds like an exhaust rattle but the exhaust is sound and when I get close I can tell it is coming from the engine.  I also have a Cub Cadet 1811 with a Kohler Magnum 18 and it runs about at about half the volume with no rattle.  The engine starts and runs fine with no smoke but I am afraid that there is something that I should have repaired before it blows up or something.  I have used it some and the other day it blew out a head gasket and thus burnt a hole in the cylindar head.  I replaced all of it and was hoping the sound may have been a bad gasket but the noise remains.  Any suggestions.  Is it possible that some motors just run noisier than others?  Any suggestions would be greatly appreciated.

Thanks much,
Rohn Peterson

Answer
Excessive exhaust noise can come from a couple thing.  A broken baffle in the muffler.  The weld broken where the exhaust tube is welded to the engine.  Leaking exhaust manifold or manifold gaskets.  Be sure you have the correct muffler for the application.  It usually is not the engine but rather the tractor.  If you have an exploded view of the tractor and all the parts compare to what is on the tractor.  It is also called an IPL illustrated parts list. If you do not find it let me know.