Re: Mercruiser 4.3 Knocking noise when idle
Hello Adam and welcome to iBoats.
Noises are the most difficult to diagnose 'over the phone'. Only you can hear it, and you tell us what you hear. And here's where it gets messy. Your interpretation of a noise might be a 'tick' for example. Now I have in my mind what I think of as a tick, but the noise you call a tick, I call a click. See where I'm going?
So, some questions about your 'annoying knock'...
1. Does it come on as soon as the engine drops to idle or does it develop as the engine idles? If it develops, how long does it take?
2. Is it there regardless of which gear the drive is in (neutral/forward/reverse)?
3. If you lift the engine speed without load (drive in neutral), is it still there?
4. At what engine speed does it disappear?
5. When it disappears, does it go away gradually or immediately?
6. What frequency is the the at? (half engine, full engine)... ie, is it timed to the engine?
7. If the noise is there at idle without the drive in gear, have you tried it on the trailer?
8. If so, and it's still there, have you run the engine with the drive removed (to rule the drive out)?
Chris....
(8 questions...
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