I replaced the trashed lower unit on my 30hp with a used one. Everything seemed to go fine and the motor runs and pumps water but it now is very loud. Seems to me the old unit had underwater exhaust and this one does not. Am I missing something?
Any more on this? Is this a '50s motor? Any motor would have underwater exhaust, either thru-hub for later motors, or via the snorkel under the anti-ventilation plate for the older ones. Are you test running on a hose hook-up?
This is a mid 90s motor. There are holes in the back of the upper unit portion where the exhaust seems to be coming out. Just wondering how it it normally supposed to work.
Check lower unit for debris, mouse nest for example, that may be partially blocking the exhaust route through the propeller. Could cause more exhaust to vent through the relief ports that are above the water line.
I went out Wednesday fishing. It seems to run fine but all the exhaust is coming out of the relief holes which makes it idle very noisy. Guess I will have to take it apart again. I am also looking for the little plastic pieces for the shifter connection. One of mine split in too when I changed lower units. Used it anyways.
