Oh Oh ..... What did I do now?

[Impulsive]

Today was the first chance I've had to get on the water since I got the boat back from the mechanic (valve job).
Sunny, warm and flat seas ..... just a perfect day offshore!
Engine performed flawlessly for about five miles (58mph @ 4600rpm) then throttled back to enjoy the view and get ready to push the stick to the max. Got back on plane and noticed the engine running rough, peaked at about 4000rpm, and when throttling back to listen, I could hear a thumping "knocking" sound from the engine. I thing it was coming from the port side (near the batteries) but can't tell for sure.
I made a video of the engine (listen to the audio) as we came back in. The engine did make it back to port OK but you could feel the roughness, even at idle.
www.desertcom.com/videos/700rpm.WMV
www.desertcom.com/videos/1500rpm.WMV
Any idea of what happened?

[Jordy]

It's hard to say, but running it after it started doing it probably didn't do anything to help it out. Hopefully it's something simple though. :(

[Rexone]

Check the valve train first. You probably wouldn't have made it back if it was a bottom end issue. You may have broken a stud or rocker so something simple. Also a simple compression check with the plugs out can tell you a lot and pinpoint the cylinder that has a problem.

[Havasu Hangin']

Sounds like a broken valvetrain component (been there...done that). Just hope you didn't drop a valve.
Probably not the bottom end if the oil pressure was still OK.

[INSman]

B ring
O ut
A nother
T housand

[DMOORE]

Pull the valve covers and inspect. Sure sound like something broke or came loose in the top end. Like HH said, hope you didn't drop a valve. Best of luck.
Darrell.

[boatnam3]

deep knocking sound probaly dropped a valve seat,had it happen to me motor was junk.dont tell me you have merlin steel heads?

[Impulsive]

My mechanic (Mario @ SoCal Speed & Marine) picked up the wee rocket this afternoon to take back to his shop and begin the "restoration" process of my sick 454 Mag. Hopefully, the damage won't be too bad, but regardless, it will be wonderful to get back out on the water.
Frustration YES ... disappointment YES ... regret NOT A CHANCE!
As my wife reminds me quite often, if it's only money, then give thanks!
Although I fully intend to make quite a "stink" if the problem turns out to be faulty workmanship by the original mechanics, the possibility does exist that the boating gods are simply testing my passion
for offshore performance boats.

[DMOORE]

Well, from what I have heard on the forums, your in good hands.
Darrell.

[Havasu Hangin']

...the possibility does exist that the boating gods are simply testing my passion for offshore performance boats.
Welcome to performance boating. If you're not living on the edge, you're taking up too much space.
I can tell you many, many stories. Like the guy who takes delivery on his $600K+ boat and literally blows it up on the maiden voyage?
No matter how bad you think you got it...there's always someone worse off...lol.

[DMOORE]

Any updates on the motor?
Darrell.

[Impulsive]

No updates yet.
Mario is in process of rebuilding the 454 Mag.
I'll certainly keep you all posted once I get it back.

[Infomaniac]

Dude that is definately a loose rocker. Not just the rattling but the "thunk thunk" noise in the exhaust gives it away.

[boatnam2]

No updates yet.
Mario is in process of rebuilding the 454 Mag.
I'll certainly keep you all posted once I get it back.
you would think he would tell you what happened before he rebuilds it.

[lucky]

humm valve Job = Noise = pushrods or jam- nut backed off -