Rod bearing inspection/verification
Ben Baird
ben at polycore-usa.com
Mon Mar 16 13:04:29 CDT 2009
It's been a number of years since I have sent in a message so please
forgive. I got a light ticking noise under load and deceleraction about 2
years ago and had pushed an oil change about 1k mile past it's due date and
the oil was a bit low when I checked it. I assumed the worst and hastily
parked the SE-R. I tried the standard diagnosis of reving engine and
listening for noise at ~3200 RPM as well as pulling injector harness on #3
to listen for noise change, but could not get enough to make a informed yay
or nay. So after 1.5 years of being parked and finally having a garage to
work in I tore the bottom end off this weekend.
I did not find any brass shaving in the oil pan. I did however find a few
pieces of what I assume is aluminum (more like mini chunks) of unknown
origin. This is teh first time the oil pan has been off in 17 years to my
knowledge (not original owner), and the peices are too thick to be bearings
(~2mm thick, not lead). They could be left over pieces from a number of
things (casting flash, aluminum from threads, or something?) and there were
only like 2-3 of them in the bottom corner of the pan. Since the engine has
been ultra reliable and only the slight tick should I be concerned about
these (it already had updated chain tensioner years back)? During
dissasembly I did find a pinhole size light passing crack in the primary on
my HS Gen 5 headers. This may explain why I could not duplicate the noise
fully when not in load doing rev testing?
Now that I have it all the way down I got my block numbers, counterweight
numbers, and rod numbers for the bearings and I know I have grade/size 1
bearings in all 4 rods. My questions are these. I so far have not gotten
any of the standard signs of bearing failure that I know of so far. I did
not see any brass, was unable to get enough change in noise while engine
running and #2 or#3 injector unplugged, and I don't see any heat
discoloration or burn oil around the #3 rod or crank like I have seen many
comment on (infact the oil is darker around 1 and 2 where the mini baffel
does not cover). Is there any other way to diagnose without actually
removing the bearing? If I remove the bearing and it is ok can I put it
back in or is it a forgone conclusion that once it's out it needs to be
replaced anyway. Is it purely academic and I should just replace the
bearing? I know a lot of the guys who have been building motors and cars
will say just do it and forget about it, but I have a known layoff coming
and money is already tight. I am trying to get my SE-R back on the road to
save fuel costs on my truck, and I miss driving it. Maybe I am just
paranoid and it's just that exhaust leak? This list still has the best
knowledge and experts on it so I came here before I ordered up 4 bearing
sets.
Other info: engine has ~250k on it, saw redline daily till parked, has HS
intake and headers and Stromung exhaust so noise diagnosis is not so easy.
Engine ran on oem oil filters and mobile 1 as long as I have owned it. No
start up clatter. I noticed the noise after driving next to a wall on way
back to work after taking clockwise onramp at about 50mph and about a quart
low (I know it's stupid). Noise is barely noticeable when not under load.
I am paranoid. lol
BTW I am still on digest, cause I have been too lazy to change it, so any
direct CC's would be appreciated.
Ben '92 SE-R still tickin, but maybe not in a good way.
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