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So, you're thinking about rebuilding
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your engine but not replacing the crank
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bearings? Yeah, we need to talk about
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that because skipping those bearings can
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turn into a why did I even bother kind
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of situation. Oh, and quick thing. Most
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of the folks watching right now aren't
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subscribed. If you like real world car
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advice without the sugar coating, tap
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that subscribe before you forget. Now,
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first off, let's make sure we're on the
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same page. Crank bearings are those
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smooth little half moon shells that sit
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between your crankshaft and the engine
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block. Their whole job is to keep the
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crank spinning smoothly without grinding
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metal on metal. When they wear down even
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a little, your oil pressure suffers.
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Your crankshaft takes a beating, and you
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start hearing knocks that aren't the
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good kind. If you skip replacing them
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during a rebuild, you're basically
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building a house on a cracked
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foundation. Everything might look fresh.
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New pistons, shiny head, maybe even new
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gaskets, but deep down, the heart of the
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engine still has the same old weak
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spots. I've seen engines run fine for a
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few months after this and then bang, a
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spun bearing, scored crank journals, and
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you're right back in the garage pulling
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it apart. Now, I get it. Maybe the crank
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looks okay and you're trying to save
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time or money. But here's the thing. You
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can't always see wear with your eyes.
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You've got to measure it. That's where
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something like plasticage comes in. It's
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this little strip you stick between the
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crank and the bearing, torque it down,
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and then check the squish to see your
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clearance. If the clearance is out of
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spec, even by a hair, that bearing has
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to go. And here's another thing. Even if
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the old bearings still measure good,
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they've already been married to that
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crank. They've worn into each other's
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shape. Once you disturb that setup by
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taking the crank out or machining the
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block, you risk misalignment or uneven
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pressure. New bearings are cheap
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insurance compared to tearing down an
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engine twice. I had a buddy, Mike, who
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thought he'd be clever and reuse his
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bearings on a budget build. He dropped
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the rebuilt engine in. It ran smooth for
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about 1/200 miles. Then he calls me
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saying his oil light came on and the
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engine was knocking like it owed him
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money. Pulled it apart, bearings were
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wiped, crank was toast. He ended up
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spending more than if he'd just done it
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right from the start. Also, keep in mind
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when you rebuild, you're usually
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cleaning or replacing oil passages,
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pumps, seals. If you leave worn bearings
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in there, you're bottlenecking the oil
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system. Less oil film means more heat
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and friction, and that means faster wear
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on every other moving part in there. So,
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yeah. Could you rebuild without
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replacing crank bearings? Technically,
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yes. Would I recommend it? Not a chance.
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It's like replacing your car's paint
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without fixing the rust underneath.
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Looks good for a while, but you're just
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covering up a problem. All right, quick
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recap. Crank bearings are cheap. They
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protect the most expensive part of your
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engine, and once you're in there, it's
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way easier to swap them than to risk a
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full tear down later. Don't gamble on
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old bearings unless you like throwing
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money and weekends into the garage for
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no reason. If this helped you think
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twice about skipping those bearings, hit
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that like button. And if you've got a
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rebuild horror story, or maybe you got
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away with reusing them, drop it in the
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comments. I love hearing those it'll be
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fine stories. And hey, don't forget to
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subscribe so you don't miss the next
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time I save someone from a driveway
