Back story:
I bought this boat as a family ski/runabout and thought I finally had all the gremlins worked out of it. Ran it for about 4 hours on a local lake, and then made a 6 hour tow to a pristine river/lake system on the US Mexico border, Lake Amistad. The boat started to give this rattle a little at idle, and I decided to run it on the lake, we put close to 20 hours on it when all hell broke loose and it began to sound horrendous. But that was in the drive line, and I don't believe related to this.

1
Please listen to the video attached and see what you think, I have heard these lifter nuts can back off and cause noise. Would that quiet down when idle is increased? It seems like this noise doesn't start until it warms up. I didn't have a torque wrench with me or I would have retorqued the lifters.

2
In the end of the video is the gimble showing how lose the lower bushing is. Would that cause a u joint to make lots of noise? One of the grease zerks from the u joint was in the bottom of the bellows, and the oil in there is drive lube. What seal would let lube into there?

https://www.youtube.com/watch?v=sWz6...ature=youtu.be


Thanks,
Ernie

1) lifters are set to spec in sequence - not torqued.
2) gear oil leak probably the Upper seal behind the yoke.

You might want to seek out a quality tech to get you squared away.

1) Pic is not very clear but you should be seeing oil on top the rockers and it should be splattering all over the place. If you don't see much oil then I would get a mechanical gauge and check the reading. It appears to be a vortec motor (did not say year of serial number), and if so nuts are torqued to 22 ft lb

2) Don't see much play but the squeak might need to replace the washer (item 9). This shouldn't effect the U joints
Genuine Mercury & Mercruiser parts. Bell Housing

That does not sound like a lifter or valve train noise. Valve train and lifter noise is a consistent tick or light knocking sound.
That is inconsistent and goes away when a light load is placed in on the engine. It almost sounds like exhaust flapper noise.

You might have a loose part in the bell housing.

what year and engine serial is a must and with all marine engines. Anyways vibration from the balance shaft can be the issue here. common 1996 1/2 thru early 2000's and or also timing chain chain / gear issues.

The boat is a 2011 model

Serial number 1A634447

Thanks for the ideas

Ernie