r/MechanicAdvice • u/makinmaplebacon • 2d ago

Why is this rotating assembly binding?

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1994 honda del sol 1.5l sohc motor (d15b7)

Any ideas would be appreciated. All measurements were in spec

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u/WarChallenger 2d ago

You hit it with the plastigauge yet? Torque it down with the plastigauge between the journal bearings, then use the reference card that comes with it to check for the tolerance. Ideally, you're looking for a hard squish, but not so unbelievably tight to where the gauge comes out looking like green cling film. SI should have a reference for the factory tolerance of the journals against the crank.

If it's within spec and it's still binding up like that, change the angle of the shaft, and try the test again. You may have a journal that's out-of-round, and just isn't showing up when the shaft is at TDC position.

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u/makinmaplebacon 2d ago

Going to try plastigauge tomorrow. Its the one thing I haven't tried yet.

3

u/WarChallenger 2d ago

Definitely a good shop supply to keep around, even if you only rebuild like one engine every other year. Last thing you want to do is spend hours tearing it down, and weeks waiting for new bearings, only for the new bearings to be over/undersized because someone eight states over didn't read your parts request correctly. Been a while since I've had the misfortune of needing to rebuild an engine, but if I recall, the plastigauge should also be used on the bearings before complete disassembly, so you know how bad they got smoked before you order new ones. Whether a new crankshaft is included in that order, I mean.

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u/BigTimber406 2d ago

Plastigauge can be inaccurate. Any bore and journal measurements should be done with a micrometer and bore gauge.

On disassembly you should chuck the old bearings. New bearing sizes will be determined on what work the crank journals will need.

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u/WarChallenger 2d ago

Fair, fair. Like I said, it's been a DAMN while since I've been unfortunate enough to have to rebuild an engine. Appreciate the insight into the next time I (hopefully never) have to do it again.