Loud Knocking Diagnosed - Spun Bearing:(

[Jim Green]

Thanks for the advice guys, I'm pretty new at working
on the bottom end of engines so this helped a ton.
I'm getting some prices from some machine shops to
have this professionally redone.  I did do most of the
work myself, so I'm not in the hole too much for
parts, but hate the thought of taking the engine out
again.  When I had the crank polished it was measured
and was still well within new specs, everything was
very clean when reassembled, but obviously I missed
something!
Jim
--- Phil Payne <quattro at isham-research.com> wrote:
> > I'd plan on replacing the rod that went out.  It
> is certainly not
> round
> > any more.  If the big end of the rod isn't round,
> it won't hold a
> bearing
> > any time at all.
>
> I wonder if that was the cause this time around.  Or
> a piece of sh1t
> trapped between rod and cap.
>
> > You ought to take all the rods including the new
> > replacement rod to a good machine shop and have
> them checked for
> roundness,
> > length, and twist.  Since the piston in the bad
> cylinder was
> traveling
> > higher in the cylinder, courtesy of the huge extra
> clearance in the
> rod
> > bearing, look carefully at the top of the piston
> to make sure it
> wasn't
> > hitting the head or valves.
>
> Top piston ring is more likely to be damaged, since
> it'll be driven up
> onto the rim it created itself.  Quite likely to
> find the top ring
> cracked, IMO.
>
> --
>   Phil Payne
>   http://www.isham-research.com/quattro
>   +44 7785 302 803
>   +49 173 6242039
>
>


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