Spun or normal wear?

[msggunny]

I finally got around to investigating a low end knock in my 2.25.

I pulled the rear con rod cap and found this:






Looks bad to me, but i dont really know.

I would assume that the crank would need turned as well if these are bad, right?

[gudjeon]

Looks like normal wear to me. The babbit (lead bearing material) is supposed to let particles embed rather than gouge up the crank surface. Thats why it is soft. The outer layer is mostly worn where most of the torque is put is normal. A spun bearing will have it's locating tabs sheared off. Only a true measurement of the crank will determine wear. Measure after a polish to yield what you truly have to work with. Otherwise a regrind by engine shop, and use undersized bearings is what I would do if its needed.

[Donnie]

I finally got around to investigating a low end knock in my 2.25.

I pulled the rear con rod cap and found this:






Looks bad to me, but i dont really know.

I would assume that the crank would need turned as well if these are bad, right?

Rod bearing wear is measured at the top bearing as the pressure is down as the engine fires
I would go to an auto supply store & get a strip of plastigage .001--.003..it may not be available unless your supplier sells bearings & engine rebuilding parts. Use this thread like material to measure the space between your crank & the bearing, place a piece on the top bearing shell, use a little vaseline to hold it while you torque the cap up to specs. this will crush the material & U can read the clearance with the scale provided on the paper envelope provided with the purchase..Have U located which cyl is knocking? if not U can find it by pulling each plug wire & paying attention to the sound.. the material will crush & you can compare it with the spec..Rod journals can be miked for roundness by a good mech by pushing the piston/rod up into the block..Do 1 cyl at a time..

[junkyddog11]

While all this is technically very correct, if it is bad enough to knock you can generally feel play by hand. Most easily felt at bottom of stroke by pulling up and down.