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Posted by M Fanoni [32.172.35.199] on Saturday, June 26, 2010 at 13:48:24 :
I have a little story for you all.
One fine day I was out driving my truck, with a 230, in the foothills. It was a relatively warm day and I knew my temperature gauge was broken, so I took extra special care to pull over let the truck cool down if I even thought it might be getting warm. I always had around 40psi oil pressure, which is normal for this truck.
After a 6 hour drive, I'm back home and I notice a slight, very slight, rattle coming from the engine. I'm not overly concerned, because it is a 60yr old motor, but I definitely keep track of it. After a short drive the next day, maybe 10 miles, the slight rattle has turned into a full blown rumble and it's time to shut it down and investigate further. It seems that I failed in keeping the truck cool on that long drive. Oops.
I take it apart and here's what I find:
rod bearings are perfect
wrist pin bushings are trashed or nonexistent
wrist pins are trashed
blown head gasket
everything else looks great
So I hone the cylinders, new rings, new wrist pins, new wrist pin bushings, new rod bearings....reassemble.
It starts unbelievably easily and runs smoother than it ever has. But at slightly elevated RPM's is has a rattle (different than the one before, almost like a cold diesel rattle) AND it's getting around 5-10psi oil pressure.
What gives? I can't explain the pressure drop, I parked it with 40psi. Unless I literally didn't install half a rod bearing, there should be no reason for the pressure drop. The low rattle COULD be main bearings, but that doesn't explain the pressure drop. The same main bearings were in it when I was getting 40psi.
My only hypothesis so far is bad main bearings (causing the rattle) and I forgot a rod bearing (causing the pressure loss and rattle). Only problem is that this is impossible because I would never forget a rod bearing.
Whaddya think?
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