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Old 09-19-2011, 05:06 PM   #1
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Default Easy ways to check for bad shortnose crank?

So I've been out of a miata for a few years, and am trying to get another.

I've found a 1990 for a very reasonable price, but it's barely running thanks to what the owner says is a skipped timing belt. It starts up and drives, but with little to no power.

If it's just the timing belt then it's a killer deal, but I'm worried that as a 90, the crank pulley could be causing the belt to skip, and might be on it's way out.

Flashlight and stare at the pulley? I'm 1.6 retarded, so if there is a better way to check if the crank is toast it would be much appreciated.
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Old 09-19-2011, 06:11 PM   #2
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i think you can just count the grooves on the pulley. or this


search X 10 before you ask.

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Old 09-20-2011, 06:54 PM   #3
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He was asking how to tell if it's bad, not how to identify it as a short nose crank..

Unless you can feel movement in the crank pulley or you can see it wobbling while the engine is running then I'm not sure you could tell without removing the pulley and having a look.
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Old 09-27-2011, 11:16 PM   #4
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Could be the balancer.

Bring it to TDC and check the TDC mark.

Its hard to time if the mark is in the wrong place.
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Old 09-27-2011, 11:23 PM   #5
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I would assume the worst and make an offer based on that.
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Old 09-28-2011, 07:01 AM   #6
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The obvious thing is to look for wobble. Beyond that, you find it on a TB job.

Also, I wouldn't worry about it. The Locktite fix is pretty much a cheap, effective and permanent repair. I've got 40K on mine now (~8K turboed), and I started with a worn keyway and pulley wobble at 150K.

If you've got a decent, unhacked car with no corrosion, go for it. Mechanics can always be fixed.

Last edited by hornetball; 09-28-2011 at 07:13 AM.
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Old 09-28-2011, 07:10 AM   #7
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Harbor freight sells a magnetic stand and dial indicator for less than twenty five bucks. It's a pain in the *** to set up because the magnetic post is cheap but It'll do the job. I don't know what the runout should be so check the service manual for that.
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