Quote:
Originally Posted by chocstraw
...Isn't the main issue actually the notch on the lip of the bearing wearing down, causing it to spin?
|
Not sure where that came from, but it's wrong. The locating tang doesn't wear down and also doesn't play any role in bearing operation after the installation. The crush holds the bearings in place, not the locating tang. Hopefully this didn't come from a mechanic.
While we're talking about myths, here's two other myths to dispel.
- I've seen somebody say the blocks were machined wrong and the main bolts were machined at an angle. That's a myth. CNC's machine the blocks and can't even make this type of mistake.
- Factory workers torqued rods incorrectly. That's another myth. Machines do the torque sequence, and they get it right every time.
Quote:
|
Hard to imagine that any level of incorrect installation would cause such a catastrophic failure as demonstrated here. Can anyone chime in how incorrect installation could lead to seizing like this?
|
It's actually quite easy. I've seen both of the following:
- Locating tang not properly seated in the housing and was rotated 5+ degrees in the housing. This caused excessive pressure on the shells, and spun a bearing in less than 10000 miles. This failure was discovered because the shells leave an impression on the backs of the rod housing. Aligning the bearing manufacturer marks in the housing and you see the shell was rotated 5+ degrees. The locating tang was also polished -- as a clear sign that it was rubbing against the housing.
- One shell was installed backwards (locating tang on opposite side of the housing). This has similar results as the one above: excessive pressure, excessive wear, then a spun bearing. This on was discovered by lining up the scrape marks on the shells until the two shells matched. This lead to the discovery that one was installed backwards. The locating tang was also polished on this one because it wasn't anywhere near the pocket that it's supposed to fit in.
Last but not least: there was one forum user on here a few years ago. He was one of the most vocal disbelievers in the rod bearing clearance issue. He mocked everybody who changed their bearings (sound familiar in this thread?). The guy's engine threw a rod out the side, and he quietly disappeared -- and I've never seen him post ever again.