2008 F-150 4stroke Knocking noise

[21seahunt]

Hello everyone, new to the forum. Yesterday as I'm coming in from a day out the motor began making a knocking noise. Whether in idle or if I rev up the engine same noise persists. Maintenance has always been done by Yamaha recommendations . Oil was full. I replaced the spark plugs today, and no change. Almost sounds like valves tapping but I don't think it's that. Here's a little video, any opinions are greatly appreciated!!

https://youtu.be/fypIbQ_n0IM

[Sequoiha]

That's a pretty deep noise, I would pull the gear case and run it again, this will eliminate the gear case or prove it.

[TownsendsFJR1300]

Pull off the engine cowl and now listen. A screwdriver to the block and the handle to your ear may narrow down where its coming from.

It sounds, from the video, as if it's the power-head itself (and its not a loose valve), way too deep a noise.

Was your engine due for balancer replacement and if so was it done before ANY
of the old balancer came apart/shredded?

In any case, don't run it more than you have to.

[21seahunt]

Pull off the engine cowl and now listen. A screwdriver to the block and the handle to your ear may narrow down where its coming from.

It sounds, from the video, as if it's the power-head itself (and its not a loose valve), way too deep a noise.

Was your engine due for balancer replacement and if so was it done before ANY
of the old balancer came apart/shredded?

In any case, don't run it more than you have to.

Thanks for the reply's! We haven't done anything with the balancer replacement. We've been going by the recommendations from the Yamaha service maual and didn't see anything in there about that. Would that possibly create my issue? I'm going to look in to it. Thank you!

[21seahunt]

Also, from what I understand if it were the harmonic balancer the motor would have had a bad shake and all over the place also a loud whine, which I never noticed.

[TownsendsFJR1300]

The balancer issue WON'T be in the shop manual. Its not a replace after 1,000 hours, etc. Its short of a re-call but Yamaha knows of the problem and was addressing it..


Their supposed to whine when failing.

I've never noticed it when my boat was at the marina, it was mentioned that they (mechanic) could hear it. It was under warranty and was replaced.

My understanding is the units shread some material which will get in the oiling system and cause blockage. That's what destroys the engine, lack of oil to bearings, etc...


Some F150's don't have the balancer at all and its been posted here, there's very little in-balance on those engines...

Its a very stout/heavy unit, basically two very heavy duty short crankshafts with gears that run off the crankshaft..

[21seahunt]

Thanks Townsend. Unfortunately I have a feeling that's what I'm dealing with. Some have said the motor would have been jumping around or rattling if that was the case, but it's not. And some of the videos I've seen on line don't either. But the mechanic will pull it out of the water tomorrow -Wednesday. I'm hoping it's not too bad, but that's just hopeful thinking. I will keep you guys posted on what his findings are. Wish me luck 😩

[TownsendsFJR1300]

Good luck of course and yes, please post back (pic's would be great if possible)..

[palmiben]

I have the same noise. What was the result here?

[TownsendsFJR1300]

I have the same noise. What was the result here?

That Op hasn't posted in 3 years...

Might want to start a new thread, with specific's and video/audio..


.