Hi guys, any help appreciated here. I have a 1988 oil injected 115 on a 19ft fibreglass run-about that has served my family well and is very reliable. However, for some time now, I can hear an engine noise that seems to occur in a fairly narrow rpm range of 4200 to 5000 RPM. It will only occur when we are going dead straight with the engine trimmed for max speed. I can make the noise stop by very slightly turning the steering left or right.
The RPM won't really change when I make this adjustment.
To describe the noise:
-it is not much louder than the engine noise.
-it has a slight ring to it.
-it sounds sort of like chain running really quickly over an anchor winch. Kinda like a rapping with a ring to it.
-if I had to guess, I would say the rap is about the same frequency as the engine or maybe the ignition frequency.
If there is any way that I can better characterize the noise or clarify for you please just ask.
Could this be pre-ignition? or pinging? What does that sound like? what causes it? If it does sound like one of these things, why would it go away when I turn the engine a little bit one way or the other?
Thanks for your thoughts.
The RPM won't really change when I make this adjustment.To describe the noise:
-it is not much louder than the engine noise.
-it has a slight ring to it.
-it sounds sort of like chain running really quickly over an anchor winch. Kinda like a rapping with a ring to it.
-if I had to guess, I would say the rap is about the same frequency as the engine or maybe the ignition frequency.
If there is any way that I can better characterize the noise or clarify for you please just ask.
Could this be pre-ignition? or pinging? What does that sound like? what causes it? If it does sound like one of these things, why would it go away when I turn the engine a little bit one way or the other?
Thanks for your thoughts.