At 07:02 AM 9/21/2000 -0400, Carl W French wrote:
>.... I would be sure to mic the crank, can't answer your question about
cleaning up the surface of the crank. That is for Barney, I am sure he has
done this once or twice on some roadside in the rain at night :-)
ROTFLMAO. Yeah, that sounds like me alright. Never done that on the
roadside, only in the garage, although I have replaced a crankshaft in a
parking lot. On a couple of occasions after a "slight" and very short term
oil starvation problem cooked a rod bearing (one only) I have polished the
remains of the white metal off of the crank journal (with 600 grit emery
paper and oil) and installed new rod bearings (all of them at once).
Now here is a series of IF's. If the crank was in particularly good
condition to begin with, and if the bearing went from quiet to light
tapping in a short time, and if it was not run too much afterwards, then
maybe the crankshaft could be okay. You have to disassemble the suspect
bearing for inspection.
If the bearing still has 100% white metal surface, and if the crank journal
is still smooth to the touch (absolutely no detectable roughness), then the
crank is probably okay, but you should still check the big end of the rod
for out of round condition.
If the bearing has gone all the way through the white metal and has some
copper showing, then the crank is more questionable. It still has to be
perfectly smooth to the touch, and additionally you should mic the journal
to be sure it's still round and full size, and check the big end of the rod
for out of round. If all that checks out, then a little polishing of the
journal and new bearings should suffice.
If the bearing has gone all the way through the white metal, and all the
way through the copper backing, and has the steel shell showing on the
inside, they the answer is very simple. The crank journal has been scored,
and the crank will have to come out for a regrind, so get to work pulling
the engine.
>Check/rebuild/replace the oil pump?
Uh, yup. Always check the innards of the oil pump any time there has been
a bearing failure. All smooth surfaces are required on the mating parts of
the rotors, and 0.006" maximum clearance between the apexes (measure with
thickness gauges). If in doubt, check to see if it is at least self
priming. Put a few drops of oil in the pump and turn it to expell the
excess, just enough to wet the rotors. Then stick the inlet end in some
oil and turn the drive shaft by hand. If it self primes at one or two
revolutions per second it should be useable. If it doesn't self prime it's
junk.
>> it had a rod bearing
>>out, it was in the bottom of the pan in pieces. The crank looks
>>undamaged, no nicks, gouges, etc. is this unusual as i was driving the
>>car when it started knocking? I plan on replacing that one rod bearing
>>and getting back on the road, any reason not to?
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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