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Thread: Main Bearing Damage (R.I.P)

  1. #1
    Ok....After this thread I will let the death of my BBC rest in "a-peace"
    We know I lost a rod bearing which was found because I had a dead cylinder. After further removing the crankshaft today I found the main bearings to be in even worse condition.
    Now my engine builder built the shortblock and I installed the cam, heads, and the rest of the whole parts. I just want to know what went wrong and why?
    Was it me? Was the builder?....No I'm not planning to take the builder down hard...I just want to know for future knowledge and experience.
    This is my take on it. See the copper trail starting show where the crankshaft oiling holes are located? I wonder if it was some major contamination of the sort that fed the entire oiling system and destroyed the motor. Wouldn't that be part of the proper clean-up effort prior to assembly? I would think so...
    Or was it my carburetors?...Yeah I think it was the carbs
    What's your take? Infomaniac, Lakes, O58, Gnarley,.....hell....HOSS!
    #1 Main bearing...
    Thrust bearing...both side and bottom half...

  2. #2
    You had a lot of crap go through that motor.

  3. #3
    Not to mention those bearings are ONLY 55 minutes old....WTF? It's like I used 20W/50 mixed with some special sand...

  4. #4
    I thought you built it?

  5. #5
    Nope....due to a deadline crunch of Wes and I getting the boat rigging and wiring complete and all the polishing/powdercoating efforts...not to mention carpet....I decided to have my machinist assemble the motor. I actually personally know the Gary, the guy who assembles the BBC's for Ed Hale Racing engines.
    Who could have been improper prep before could have been a dirty oil pan. Fortunately enough I bought a new pan from Rex Marine and it was thoroughly clean before installation. Every other variable I could think of has been checked and rechecked....
    Hell just for Bull shitting's sake I wouldn't mind having these bearings tore down even further with a microscope....but's just a Chevy

  6. #6
    You're looking at the aftermath damage of junk through the oil after the rod/bearing or whatever the failure was.
    The failure was the rod, either oiling, clearances, cap on backwards, wrong sizing or what have you. Probably failed in the first 5 minutes and 50 more minutes or running damaged time.
    But at best, this is like diagnosing cancer over the phone.

  7. #7
    I will have to agree. Looking at those bearings I do not see "cause" I see "effect".
    The rod bearing burned for whatever reason.
    If the main that feds that rod is burned, I would suspect that. Since it was not, the rod was by itself in the cause of the damage.

  8. #8
    I know this sounds bad, but most machine shops are used to doing the work and then sending the piece back to the owner. Then, the owner is expected to spend 4 hours cleaning, days mocking and rechecking, then assembling.
    To me, that brearing looks like a bunch of shit was floating around in your oil galleys. Typical of a sloppy machinist, who is used to machining, not assembling. I had the same problem with the famous 427 that was in the Daytona. I am by no means a seasoned bearing reader, but I saw lots of foreign metal embedded in the bearings (like they should be). I dunno man, I say clean the focker real good, measure and reassemble it yourself this time and really take your time doing it.....

  9. #9
    flat broke
    One thing you might want to consider. If it wasn't a f'd up assembly, and everything was together correctly (tollerances etc), perhaps the debris from the thrust bearing taking a beating worked its way through your oiling system.
    If you don't have a little front to back clearance bettween your driveline and the front of the pump, you can have this problem. When the pump is loaded the impeller and shaft will sometimes walk forward. If there is clearance in the coupler on the input shaft, no big deal. If there is NO clearance then as the shaft moves forward, it loads the crank and the thrust bearing sees excessive wear.
    The only reason I even thought of this was because I remember that you had just setup a new rail kit for the event. It's hard to say from the pics of the thrust bearing if it is really worn, or that is just the color out of the box. I've seen thrust bearings come brand new with some copper showing, and others with a gray color on the thrust surface.
    Whether or not it is the source of your contamination is debatable, but if it was, that is how it got that way.
    Check this fitment on the new motor install to make sure the coupler has some room to move on the input shaft before bottoming out on the front of the pump.

  10. #10
    I'm with Info on are looking at effect rather than cause on the mains. Too much garbage going thru the engine. Impossibe to diagnose from pics. Call the priest and give it the last rites.

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