Mercury 15 HP 4 stroke 2007 1B152. FB

w2much

Lieutenant
Joined
Jun 22, 2005
Messages
1,292
Beautiful low hour motor starts on a pull, idles slow and smooth. Issue is that the longer it idles the louder I hear a ping or knock. Seems to be coming from the head itself. Motor has never been opened , all of the paint and gaskets appear as on a new engine. I am not much familiar with four stroke outboards. I am guessing the valves need to be adjusted, never did that before. As for being progressively more audible. I hope there is not an oil pressure issue and thinking that as the engine warms the valves become louder. I think I have seen that there is a hot and a cold method of adjusting the valves.
Any input on this appreciated.
 

Mohawkmtrs

Chief Petty Officer
Joined
Jan 13, 2010
Messages
563
Check/adjust them cold at the top of the compression stroke (both valves closed, rocker arms will be a little loose).

Intake .006" - .010"
Exhaust .008" - .012"
 
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