Clanking sound after engine swap

[stldan]

I just swapped the engine on a 1997 Rinker Captiva 196 with a Mercruiser 4.3LX Gen+ after suffering from a cracked block. I am slowly getting closer to putting the boat in the water with lots of pressure from the wife and kids to finish this project before the end of the summer. I am trying to determine this clanking sound and am hoping that someone might have a better idea on what I should check. A video of the sound can be heard here in the attached link. Does anybody have an idea of what the clanking sound could be? Your help is greatly appreciated!

 

[Bt Doctur]

thinking loose, rocker, collapsed hyd lifter ,incorrect pushrod adjustment

 

[Bondo]

Ayuh,..... Or that wrench ya lost,.....

Welcome Aboard,..... Can ya narrow down, Where it's comin' from,..??

Maybe try the ole broomstick to the ear trick,....

 

[Speak]

Does not sound good. Loose flywheel or harmonic balancer...could be a shot in the dark. Does the engine run rough or missfire? when the knock is present?

 

[Bondo]

Ayuh,.... On a side note,....

Those exhaust manifolds are a blown motor, just waitin' to happen,......

Hard to believe they ain't already failed, dumpin' water into the cylinders,.....

Scrap those things, 'n go to the 2 piece riser/ manifolds,....

 

[stldan]

Thanks for all the responses, it is greatly appreciated!

I pulled the valve covers and all appears well. It seems to be coming from the prop side of the motor, I've put my hand on various parts of the motor and it doesn't seem to be coming from the front. I will find my stethescope and probe further but wanted to see if anyone had experienced this before. The engine runs fine for about a minute and then runs rough for about 15 seconds and then smooths out for another minute. The noise does not seem to be in relation to the rough pattern. My two latest theories are that one of the manifolds are leaking water into a cyclinder and causing the temporary roughness which is cyclical to the thermostat opening and closing. Any thoughts on this one? The other theory is about the clanking noise, perhaps my alignment is off as I went on bad information that I didn't need to realign it as long as the mounts didn't move. I ordered an alignment tool and plan on checking it soon. Is it possible that the alignment being out could cause the clanking?