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gwershing
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Posted 8 Months, 4 Weeks ago #1
I am working on an OMC (GM) 3.0L (same engine as a Chevy II 2.5L L4)

Just had the pistons hung with new pistons and new wrist pins. Two of the rods seem to swing very easily, and the other two have resistance. For example if I had the pistons on the bench with the rod up, two of the rods would fall to one side when I let go, and the other two would stay standing.
Is this difference a problem? Is there a proper amount of resistance, or will that even out over time?
I have had these in the engine and have run the engine for less than two hours. I am trying to troubleshoot a noise problem, that I think I have narrowed down to the valve train (stuck lifter) but while I have the engine apart I want to rule everything else out.
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HeavyD10000
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Posted 8 Months, 4 Weeks ago #2
Are you able to move the pistons while holding the conrods? if yes and it doesnt take much force, then ok.
If you must use even a few foot pounds than theres a problem.
gwershing
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Posted 8 Months, 4 Weeks ago #3
If you mean rotating the pistons on the wrist pin, then it doesn't take much force at all. There is just enough resistance to hold the rod in place when you let it go. They are not tough to move, then just have a little stiffness.
My concern is that when the engine gets to operating temperature, the stiffness would get worse due to expansion.
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HeavyD10000
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Posted 8 Months, 4 Weeks ago #4
That is normal resistance for wrist pins.
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