Engine vibration

Guys. I have a 2005 196 with the Excalibur motor. I've had the boat since May, and since May I've noticed a weird vibration when pulling skier up and when slowing down. I checked the usual things--alignment, prop, prop shaft, prop strut. Even got a new ACME prop and a new strut. Still the vibration persists. So, I took the boat into my trusted mechanic--expecting him to tell me nothing is wrong, just my imagination.

Wrong. He just called. They ran the boat up and felt a definite vibration in the motor as well as a heard a troubling noise. The motor has only 230 hours on it and runs great--except for the vibration which is unusual and never experienced before on my three previous Nautiques.

My mech wants to dig into the motor to find out what's wrong. He says its only going to get worse. The motor is under warranty and he's PCM authorized. My mech has been doing this work for over 30 years and builds drag boat motors. He's pretty trustworthy. What do you guys think?

Thanks BKH. I'm going to have the mech do a compression check, a fuel pressure check and make sure there are no engine codes.

I don't like the sound of a new sleeve.

SGY, welcome to CC Fan! Finally came over from PN, huh?

Good to have you on board. Great group of people here- you'll have to get to the next reunion.

once in a while the harmonic balance will go bad on the engine and will cause a vibration, who knows thank god its under warranty, would hate to end paying for that one especially if the problem was mis-diagnosed, hopefully they'll drop a new one in there for you

Thanks BKH. Hopefully its not something like that. If so, I would hope PCM/CC would replace the motor.

I a$$ume a compression check would be indicative of such a problem--more leak down in the out of round cylinder??

Thanks Eric. Fortunately, the motor is under warranty. Richard at Skidim.com told me that faulty valve seats are the first thing they see go on these motors--but only if they are relatively new. Mine has over 230 hours on it. So, we'll see. What kinds of things was the motor doing that dropped a valve seat?

Well i doubt it is an engine related item otherwise you would feel the vibration all of the time but since it is while pulling a skier or slowing only then it has to be in the drive line, bent shaft, loose bushings worn dampner plate, loose coupling.

Valve seats, harmonic balancer, piston problems will be constant not occasional and will only get worse as the RPM increases.

then again that is a$$uming you are diagnoising it correctly or discriping it correctly.

I wish it were that easy. But, I've been through the entire drive line. Replaced prop and balanced new Acme. Put in a new strut and had the alignment triple checked. Also had the shaft checked. The mechanic disconnected the prop shaft and ran the motor up. The vibration starts at about 2400 rpm and gets more prominent the higher the revs. There's also an incriminating noise in the front of the motor that is in harmony with the vibration.

How tough a job is that? Also, if it is the HB, what damage has been done to my crank and main bearing due to the torque vibration?

Thanks 79. When you say a bearing or two, what are you talking about? The rod bearings? Are there rod bearings on the rod ends connecting to the crank journals? Any damage to the crank possible?

Thanks Eric. That's a very generous offer. I'm supposed to hear more today on what they think is going on. I'll keep you posted.

Hey, I guess I just figured out my other log in. SGY1 and SteveY are the same dork.

Great news Steve. Glad you're on it. Sure seems like a weird fix though.
Mostly I'm glad to hear someone out there is still skiing. You'll have to post some pics...

Dude, where are you located? I'm in the Denver area. Water is getting fairly cold. We pulled the course last weekend and now are just free skiing for excercise.

Thanks to everyone who provided helpful advice. I just wish it were July again.