Merc 115 cooling

[fish281]

I have a '03 115 HP (non EFI) engine. Noticed when flushing it this week that it occasionally "coughs" at idle, and when it does the pee stream coming out of the cowling stops for just a second. Also noticed that the stream has a slight smell of 2 stroke oil. No major issues with how the engine runs at speed or at idle. Compression check shows everything within the 10%.

Was wondering if I have a bad gasket that is allowing the combustion gasses to escape into cooling water stream when it misfires.

Thanks.

 

[CharlieB]

Re: Merc 115 cooling

A 'cough' at idle is often a 'lean' misfire, symptom indicating a carb cleaning may be necessary.

If the motor has always had this then an idle mixture adjustment may solve it.

If this is a new problem then carb cleaning is highly recommended.

P stream flow will momentarily stop or reduce remarkedly as the motor (and water pump) momentarily slows during the cough.