First let me say I have not heard this in person. Just descriptions over the phone. Friend is saying that he is getting a "knocking" sound only under loan and only over 2400 rpm. He had someone look at the valvetrain and it was good. He said the noise sounded more like something in the drivetrain. He pulled the drive and the and the u-joints and gimbal bearing look good.

Could a cracked flywheel or damaged coupler make a knocking noise? It's a Volvo SX drive mated to a 5.7.

Had that same problem in one motor when I had my formula. Turned out to be loose flywheel bolts. Good luck.

Thanks at least that's a place to start!

sounds like the coupler. Pull motor and install new one. Bring wallet.

Bring wallet. True story, lol

Thats what Ive been dealing with too...Is your tapping/knocking sound coming from the bellhousing?

http://www.offshoreonly.com/forums/g...ing-noise.html