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small backfire sound when turning engine over by hand?

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Old Sep 10, 2010 | 05:06 PM
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Default small backfire sound when turning engine over by hand?

anyone ever have any weird stuff happen to them while turning their engine over by hand?

i was on the passenger side of the car, turning the engine counter clockwise and then i heard a weird backfire type sound, but quieter.

this ever happen to anyone else?

what could this be?

i have three potential scenarios:

1. i was leaning over the accumulator so i guess i could have leaned too hard and opened up the closed lines of the a/c system, letting freon out? i doubt it would make a backfire sounds though. i would expect more of a "newly opened coke bottle sound"

2. broke loose or untorqued the harmonic balancer bolt. i doubt this happened because my six speed car was in neutral.

3. an actual backfire occured. i doubt this could happen because my intake manifold has been off for a long time and so has my passenger side head and my fuel system cant be pressurized at all.

anyone else have any suggestions of what this could possibly be?
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Old Sep 13, 2010 | 10:18 PM
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bump!
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Old Sep 13, 2010 | 11:50 PM
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From: Turnin' Wrenches Infractions: 005
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Why were you turning the motor counter clockwise? It is normal to hear air moving noises as the motor is being turned bc, well, its a big air pump.
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Old Sep 14, 2010 | 12:49 AM
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yes counter clockwise.

the noise that i heard was something more/louder than the normal sounds of the engine compressing and relieving air.

it it helps any, my plugs were out on the passenger side but not the driver.

maybe that was the sound? pressure/air coming out of the spark plug orifice?
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Old Sep 14, 2010 | 01:05 AM
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You made it sound like you got that thing moving over 2500 rpms by hand!
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Old Sep 14, 2010 | 06:07 PM
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Originally Posted by 01ssreda4
Why were you turning the motor counter clockwise? It is normal to hear air moving noises as the motor is being turned bc, well, its a big air pump.
just saw that you asked why.

i was turning it that direction because it was the direction that was most convenient for me.
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Old Sep 14, 2010 | 10:49 PM
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Huffing or hissing sounds are expected when rotating an engine. If it's quiet, then it doesnt have any compression. That sound is how most backyard mechanics find TDC for a cyl
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Old Sep 15, 2010 | 01:35 AM
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i have turned the engine over by hand to find TDC to torque down the rockers and to determine my proper pushrod length.

this was louder than that but i guess it is nothing major and not something that has happened before to anyone else.

either way it will probably present itself in the future. if i broke the harmonic balancer bolt loose, i have to take my cam out anyway so that is only helping to speed up the process.

if i released my a/c system's freon out somehow, i'll know it was that next time i turn my a/c on.
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