One of the cooling exhaust has more pressure than the other, is this normal?

[Justy23]

Hello, yesterday I had my first experience in the water with My 2001 Challenger with a Mercury 200. I notice that at idle speed the engine sounds like pistoning if this is normal? or could be the fuel (not been premium). In addition I notice that one of the exhaust tubes has more pressure than the other. Is this normal? in general terms the boat ran well.

 

[Dr Honda]

Not sure what you mean by "pistoning". Also, what tubes? The big ones between the expansion chamber and the mufflers?

 

[Justy23]

Hello Dr. Honda
I mean the big tubes coming out from the mufflers under the swim platform I think this is the exhaust discharge. The right side when viewed from behind does not have a lot of pressure when compared with the other. This is when the boat is in the water. By pistoning I mean that at idle speed in the water I heard like a metal sound in the engine. It disappears when I accelerate the engine. In the cars a sound like this sometimes means a bad fuel or a low octane fuel.

 

[Dr Honda]

Ok. The sound is normally called "knock". Knowing you were asking about the ignition timing... I would recommend checking it. Too much timing WILL burn holes in the pistons.

As far as a visual on the exist... that's not a real measure of anything. If you think there is a problem... check the engine compression, and make sure the large rubber hoses have not delaminated. (you will have to remove them, and look inside)