Friend's boat developed a slight vibration. Replaced u-joints and gimbal bearing and it was still there. Now oil pressure has dropped considerably. He is going to drain the oil and cut the filter for inspection. But, in the mean time has anyone experienced this or maybe has an educated guess? I realize the list of "could be" is long but hoping to get pointed in the right direction.

Bearings.

Scott, bearings will vibrate to the point of feeling it without an immediate loss of oil pressure? It vibrated for awhile before the oil pressure dropped.

Broken piston(s) or crank and then bearings ? Or yeh, just some bearings.

I was tring to be short and sweet.

Motor is going to have to be taken out and inspected anyway...so I couldn't go wrong by saying bearings.

:wink:

Outer ballancer slipped?

It does not explain loss of oil pressure

A piece of a Jelly Donut got stuck to a piston and then fell off and is now clogging the oil pump screen.

That's my guess and I'm sticking to it.

JRider, what do you mean outer balancer? I was thinking something happened to the coupler or harmonic balancer/damper causing the vibration. Then the vibration wiped the bearings.

Lol. I guess at this point it doesn't matter. But I would like to know what possibly caused it and what to look for.

Or shook off the oil pump pick-up.

There are many, many different scenarios like you mentioned in the first post.

Impossible to guess. We'll sit and watch to see what you find out.