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Old 05-03-2009, 01:10 PM   #1
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Default Difficult to turn crank through a particular angle?

Trying this question over at m.net, but I figured some mt'ers might have some good insight as well.

Doing the timing belt and water pump job on a Miata which I purchased with a non-running engine.

Determined the non-running-ness was due to the crank orientation being off from the cams by like 40 degrees.

About ready to put the timing belt on and start buttoning everything back up, but before I do I wanted to ask- is it normal for the crank to become difficult to turn as it approaches/passes the mark on the block located between 9 and 10 o'clock (circled in yellow in the picture below -note- not a picture of my crank, just one I found online so I could circle the mark which corresponds to where it's hard to turn past).

Turning it by hand, it seems to take pretty constant effort through most of a whole rotation, except it consistently gets noticeably harder as the keyway approaches this mark on the block. It returns to taking the normal constant effort shortly after it passes this mark.

Plugs are out and timing belt is off.

Not sure if this is normal and wanted to check before I bolt everything back together.


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Old 05-03-2009, 03:16 PM   #2
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Definitely not normal...something is binding.

Turn the crank so that each piston is a TDC (Top Dead Center) and measure the exact height of each piston in relation to each other.

This sounds like a bent connecting rod.
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Old 05-03-2009, 03:26 PM   #3
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That or a bad bearing. I once accidently put one of my old bearings in with one of my new bearings when rebuilding my engine. I believe it was on the crank. Once I torqued the caps down it wouldn't turn at all. But put a rod down the plug holes and measure depth to make sure they're the same, either way you're probably going to be pulling the engine.
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Old 05-03-2009, 03:36 PM   #4
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Quote:
Originally Posted by mrtonyg View Post
Definitely not normal...something is binding.

Turn the crank so that each piston is a TDC (Top Dead Center) and measure the exact height of each piston in relation to each other.

This sounds like a bent connecting rod.
I'll check for a bent rod this afternoon. It'd surprise the **** out of me considering that it's an automatic, and all of the church flyers I found in the car, and all the long grey hair, and the 'whale song' cassette I found in the tape deck...

But it's worth checking, no doubt.

If they all come up to the same height, I'll button things back up and do a compression test. If that comes back fine I'll try to start the car and then proceed with the manual tranny swap.

Right now, apart from checking for a bent rod, I'm thinking the extra resistance is the automatic tranny's fault (it won't shift out of park).
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Old 05-03-2009, 06:50 PM   #5
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Surely pulling the autobox off and checking again is going to be easier than checking if a rod is bent. Especially as you intend to change to a manual anyway!
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Old 05-03-2009, 07:07 PM   #6
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yes putting a stick down a hole is much harder than yanking a tranny off.
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Old 05-04-2009, 03:43 AM   #7
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It is when he has to do it anyway.
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Old 05-04-2009, 01:02 PM   #8
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you cant put the tranny in neutral? if it is in park then yeah your **** wont move. lol
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