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Crankshaft Bearing Flaking

  • Thread starter Thread starter caltrop
  • Start date Start date
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caltrop

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I have a recently acquired 1980 GS450L with 25.5k miles on it. I've disassembled the entire engine for inspection and overhaul because I know it's been left to sit for extended periods and may have been otherwise abused, and I decided to get most of the surprises out of the way up front. The engine seemed to be running ok before I took it apart.

Upon cracking the case, I discovered some flaking of the main bearing inserts. Primarily it's the left center crankshaft inserts (pictures below). They show (relatively) large areas where material appears to have flaked off, as well as areas where the flaked-off material appears to have adhered back on. All bearings exhibit at least small pits, however.

I have a basic understanding of engine workings (recently finished training as an aircraft mechanic), but little experience or wisdom. Basically, I'm wondering what else I should be looking out for if I've found my bearings in this state. I'm going to check the crankshaft runout just as soon as I can get my hands on a dial indicator, but what else should I be sure to check out?

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That is not a good look for a plain bearing shell, suggests engine run without filter at some stage. What`s the crank like? Oil pump need`s to be checked for damage as well.
 
Crankshaft looks pretty good. There are small spots on the journals that appear to be very shallow scoring running parallel to the axis (though why it would be scored like that is beyond me, so I'm probably misinterpreting what I'm seeing). I've included pictures of the worst spot below. Checked the run-out, and it was immaculate. Haven't check the oil pump out yet.

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Polish the spot(s) you can see with crocus cloth, replace the bearing shells, clean the crankcase halves and plasti gauge the journals. If all is ok, check the oil pumps condition, put 'er back together, connect up an oil pressure gauge, pull the clutch lever in, turn the key on and thumb the start button.
 
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I've seen bearing damage like that before on motors which have been stored for long periods. I believe it to be the result of the porous bearing shells absorbing water then when it's fired the water heats and "pops" the pits out that you see.The scoring on the shells is caused by the material from the pits.
If you have a crank shop local to you, have the journals linished - effectively a polishing process - which will remove any edges left by the shell debris.
Given the general condition, I wouldn't be surprised if there's the odd pit in the rolling bearings too...easy enough to change those while you're in there.
 
Thanks for the info, and especially thanks for the links, Rusty. I had a look at the oil pump as per y'all's suggestions and, sho nuff, looks like it's had something a little harder than oil going through it. Rotors are all scratched and gouged (photo doesn't show all of it).


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Guess I'll add that to my list of items to replace.
 
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