Re: TECH:Trying to confirm rod knock

["Dave Ewing" <rabbit16v@prodigy.net>]

Not true Curt!!  You can replace the bearings even if there is a slight
knock without grinding the crank.  Depends on the wear but it has been done.
Just depends on the financial situation of the owner.  Obviously replacing
or grinding the crank is reccomended but may not be necessary.  You can
replace the mains without pulling the motor or trans also.  Just need to
plastigauge the rods and mains, measure the rod journals if there is a
bearing problem but most importantly inspect them for any abnormality.  IF
the crank needs to be ground or replaced it can be done in the car by
pulling the trans and using an engine support tool (or a 4 x 4 with a
chain).  HTH!!

Dave

> Chris - if it's a main bearing you need to at least put in a crankshaft
kit (reground crank + bearings) - which means pulling the motor - or maybe
drop another motor. But, if you're not noticing a drop in oil pressure or a
loud knock when you first start the car, then that points away from the
bearings. I'm wondering about a wristpin, that seems to fit all the
symptoms.
>
> What I'd suggest is: if you haven't already, do the plug wire test by
pulling the wires one at a time and revving the motor. If the knock quiets
down or goes away when one particular wire is removed then it's either the
wristpin or the rod bearing on that cylinder, or a main bearing adjacent to
it. You can further check the #2-3-4 main bearings by pulling two adjacent
wires, for instance if the knock gets quieter when you pull #1 or #2 and
even quieter when you pull both together, then it points to the #2 main
bearing (between cylinders 1 & 2).
>
> When you pulled the oil pan did you check for metal flakes in the bottom
and in the oil pump strainer? If it's a wristpin, you should find the
circlip laying in the oil pan too.
>
>
> On Mon, 22 Oct 2001 23:08:57   chris gonzalez wrote:
> >> could be something else entirely. Does it get louder under load? Do
> >yes.
> >
> >> you have an oil pressure gauge and if so has the pressure dropped?
> >oil pressure gauge shows no drop in pressure.
> >
> >if it is a main bearing, what are my options?
> >
> >thanks for you input,
> >chrisg
> >'82 8v
> >'88 16v
> >
> >--- Curt Voss <curtv@eudoramail.com> wrote:
> >> In my experience a worn rod bearing always knocks loudest in the
> >> first few seconds after you start the car until oil pressure builds
> >> up, so it doesn't sound like a rod to me. Maybe a main bearing, or it
> >> could be something else entirely. Does it get louder under load? Do
> >> you have an oil pressure gauge and if so has the pressure dropped?
> >>
> >> ---
> >> '86 Scirocco 8V, soon to be sold
> >> '82 Scirocco 1.8 8v - the daily driver
> >> '81 Caddy
> >> '78 Rabbit 1.7L rustbucket in semi-retirement
> >> '86 Celica GTS
> >> '02 PT Cruiser - the wife's boat
> >>
> >> On Mon, 22 Oct 2001 22:31:19   chris gonzalez wrote:
> >> >the patient: 88 cabriolet 1.8 8v (all stock).
> >> >the symptoms: start the car and everything sounds fine at idle.
> >> slight
> >> >ticking from the hydraulic lifters, but nothing out of the ordinary.
> >> >rev the car, and it still sounds normal. get it and drive the car up
> >> >the block still normal for about 1/2 mile, then a dull knock knock
> >> >knock that varies with engine speed. used a mechanics stethoscope
> >> and
> >> >the sound is apparently coming from the vicinity of the oil pan/
> >> >automatic transmission.
> >> >
> >> >I pulled off the oil pan and could not see anything out of the
> >> ordinary
> >> >(with my untrained eye, that is). connecting rod bolts are all
> >> there,
> >> >and torqued, at least...
> >> >
> >> >Should I go further and pull of the rod bearing caps and inspect the
> >> >crankshaft? I figure if a rod is knocking it's "gonna leave a mark."
> >> >Has anyone used the "ground out the spark wire trick"?
> >> >
> >> >Or could it be entirely something else?
> >> >
> >> >TIA,
> >> >chrisg
> >> >'82 8v
> >> >'88 16v
> >> >
> >> >
> >> >
> >> >
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