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Crankshaft locks up when installing #1 piston.
Topic Started: May 14 2013, 03:30 PM (635 Views)
chinostripe
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I installed the #1 piston and torque the rod cap nuts to 26 f/l. The plastigage said about .001 clearance. If I'm reading the manual right that's way too small. I put the old rod bearings in and torqued again. The crank will not rotate. I installed #2 and #3 using new bearings and the crank turns freely. I can install #1 and tighten the nuts with a 1/4 drive ratchet and the crank turns, as soon as I start torqueing the crank seizes and will not turn.

I have cleaned and recleaned, removed and reinstalled several times, same result every time. It's the same piston, rod, bearing that came out, the piston and rod cap are oriented correctly.

????
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Johnny Mullet
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Fear the Mullet

Time to break out the micrometer and measure the crank journal.
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metromizer


and check the #1 rod big end's inside diameter with a dial bore gauge.

Tip: Calibrate the dial bore gauge with the same 1"-2" micrometer that you use to measure the crank's rod journal. Either tool can be off a little, but as long as they are cross calibrated, the clearance you calculate will be very accurate, which is what matters most.
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chinostripe
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Nothing has changed except disassembly. I realize there is a clearance problem. Something else is going on since I'm using standard size bearings. Both new and old sets. I think the ends of the bearings are being compressed causing them to expand. I'll get it figured out.
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Old Man


check the lineral end play before installing #1 rod. when #1 rod causes the freeze up check the lineral end play again.
you may be thinking that it is a rotational freeze up when it might be a lineral freeze up
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Papa_G
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Chino. Check the part #'s on the bearings and make sure they all match. Check the boxes AND the bearings themselves. I've seen times when the wrong parts were packed in boxes. It's a long shot, but I have seen it happen.
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metromizer


Is it possible you got the rod caps mixed up between rods, or have the #1 rod and cap correct, but the cap was re-installed 180 deg out?

You probably already know this, but rods and caps are typically marked near the parting line.
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Papa_G
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:gp
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chinostripe
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As I said rods and caps are correct and they are oriented correctly. I have a suspicion, and another rod.
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490k


Put #2 rod on #1 spot. No lock up it's the #1 rod.
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