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strange banging noise
01-31-2014, 04:26 PM
Post: #1
strange banging noise
I recently purchased a 2007 Chevy Impala with 57K on the odometer I've had the car a little over a week, this morning while driving home there was a banging sound coming from the dash board area, I turned off the radio it persisted a rapping sound like someone hammering lasted about 50 seconds and stopped, drove a while longer and the same thing happened again, any clues here!!! and, please don't tell ne to just take the hammer away!
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01-31-2014, 08:01 PM
Post: #2
RE: strange banging noise
Was the heater fan on? My first guess would be that the squirrel cage is coming loose or someone dropped something down defroster vent and it made it to the fan. Try changing the fan speeds if it happens again. If the sound changes you will know where to look.

Please let us know if that was it.

Thanks for using the forum,
Garner

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01-31-2014, 10:36 PM (This post was last modified: 01-31-2014 10:39 PM by Rupe.)
Post: #3
RE: strange banging noise
Next time it happens notice if it chances with engine speed, road speed, brake application, etc. You may also want to inspect the lug nuts just in case one fell off and is rolling around inside a wheel cover.

As Garner mentioned, there's other things. I have seen frozen (and dead) mice inside the heater blower make noise. Usually mice bring food with them too so don't rule out the stray acorn if the noise changes with blower speed.

Now, if this noise is more like a rapid bang, bang, bang, and changes with road speed it could also be a CV joint starting to go bad. These are part of the front drive axles and when the rubber boot tears they go bad. Usually this gives you a serious shake or vibration as well.

If this noise changes with throttle AND engine speed it may be a cracked torque plate, which is between the engine and trans. OTOH, that usually doesn't go away by itself BUT can get worse with time.

Tell us more and we will do what we can.
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02-14-2014, 04:45 AM
Post: #4
RE: strange banging noise
Garner hit it right on! it is in the heater system when I have the heat set at max it (the noise) happens when I just dial down the temps it stops, waiting for drier weather to get a look in the system, thanks for the info.
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02-14-2014, 10:41 AM
Post: #5
RE: strange banging noise
Thanks for getting back to us! So few people take the time to let us know what they find. May-be you can tell us what you find in there if you ever get the drier weather? Good luck.

Thanks for using the forum,
Garner

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02-14-2014, 11:05 AM
Post: #6
RE: strange banging noise
Yes, thanks for the follow up.... and now a suggestion since we have more infor to work with.

If it changes with temp and not blower speed there are small actuator motors that work the blend doors inside the heater case. These motors have small gears that have been known to strip off. What you will need to do is locate the motor in question and watch it closely while you work the control to confirm this. When you remove the motor you must work the door by hand to figure out if it's binding due to debris within the case or if the gear is just worn out. I have seen situations where the heater case does not need to be removed but can be cleaned with some imagination either using a shop vac or compressed air (blowing or sucking) through where the blower mounts or fishing around after removing the floor duct. Heck, you may even be able to use a wire coat hanger if you are lucky and can see what's in there. Full travel = a solid "thunk" in both directions just like a small door closing.

Good luck and keep us posted.
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