knocking noise from engine

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  #1  
Old 08-10-07, 08:36 AM
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knocking noise from engine

have a 2001 olds alero 3.4l just had intake gaskets done about 1 month ago
last night my said when she got off parkway engine stalled when she re-started their was a noise comming from engine she said it sounded like a
machine gun going off. anyone have any ideas
 
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  #2  
Old 08-10-07, 10:45 AM
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Yes
I think the car was not actually stalled (or totally stalled)
It was still running...or at least still running enough

When she "re"-started the vehicle, the starter gear teeth clashed with the still moving flywheel (drivetrain) teeth, and that made the noise

It shouldn't have caused any damage, but I wouldn't make a habit of it
 
  #3  
Old 08-10-07, 11:35 AM
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engine knocking

maybe I wasn't clear enough the engine now has a knocking sound sounds like pistons banging or a bearing noise if i rev engine a little it gets louder
 
  #4  
Old 08-10-07, 01:40 PM
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That's not good

The knocking gets louder...does it get faster when you rev it?
Or stay the same tempo?
 
  #5  
Old 08-10-07, 03:07 PM
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How is the oil level? And what color is it?

Have you EVER had to say, "Oh my gosh, there's no oil in the engine!", and have to add some?

How many miles on the engine and is it driven around town more than highway?

Have you let the engine get overheated? And/or have to add coolant regularly?

Do YOU know the behavior of this car instead of just having your wife drive it and you not knowing what the car does (like what the indicator gauges say)?

Does the engine still run smooth with this knock?, or does it sort of lope at idle, especially. If smooth, this could mean bearing going as opposed to slop in the valvetrain that may not be opening valves equally as far anymore, like from a bad lash adjuster.
 
  #6  
Old 08-10-07, 03:48 PM
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Originally Posted by slickshift View Post
The knocking gets louder...does it get faster when you rev it?
Or stay the same tempo?
yes it gets faster
 
  #7  
Old 08-10-07, 04:29 PM
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There a number of scenarios that would give you about what you're describing. If the initial dieing/machine gun noise now has changed somewhat to the engine knocking and considering intake work was done recently, you may have had a foreign piece move from the intake through the intake valve and down into the combustion chamber where it's creating the knock now.

However you can't say the recent work is related and you may be having a completely different problem.

A sudden beginning of a loud knock like you're describing can be something on top of the piston. If you are a DIY er, I would pull all the plugs and see if any of them look beaten up. Pull them one at a time so you can identify where the plug came from.


Hope this helps,

Bob
 
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