clattering noise

Ok here's one for ya's.. I have some clattering noise going on with the car. At first when I had someone look at it we had thought it was the belt tensioner on the compressor. So I had took the car to a mechanic and explained to him what the problem might be. He told me that he took the belt off and still made the noise. So his theory was that it was in the engine and that it was a lower rod. I really don't agree that's what the problem. When I go first start the car there is a litttle clattering noise. Then when I go turn on the a/c the noise clattering gets louder. Then I turn the a/c off he noise lessens. Then I go put the car in gear (in reverse) the noise gets louder again. Then the next gear (neutral) the noise lessens, then into (drive) the noise increases again. I notice when I'm driving the car and when I go to accelerate. The noise seems to decrease. I mean if it was an engine rod. Wouldn't the noise increase while I'm driving it? I have no decrease in engine performance or no vibrations. It's usually when I am stopped at a stop light or just parked in gear that the noise is most pernounced. Also when the car was parked on an incline (the front of the car facing upwards) while in park, the car made he calttering noise. But when I went and parked in the opposite direction on the incline (the front of the car on a downward slant) and in park, the clattering noise was non existent or perhaps so low that I couldn't here it. I just don't get it. I am really baffled. Do you know what this could be?

it's a 2000 alero, 2.4L V4

It would be helpful to list the engine and year Alero you have so others can weigh-in to help.

clattering noise Ok here's one for ya's.. I have some clattering noise going on with the car. At first when I had someone look at it we had thought it was the belt tensioner on the compressor. So I had took the car to a mechanic and explained to him what the problem might be. He told me that he took the belt off and still made the noise. So his theory was that it was in the engine and that it was a lower rod. I really don't agree that's what the problem. When I go first start the car there is a litttle clattering noise. Then when I go turn on the a/c the noise clattering gets louder. Then I turn the a/c off he noise lessens. Then I go put the car in gear (in reverse) the noise gets louder again. Then the next gear (neutral) the noise lessens, then into (drive) the noise increases again. I notice when I'm driving the car and when I go to accelerate. The noise seems to decrease. I mean if it was an engine rod. Wouldn't the noise increase while I'm driving it? I have no decrease in engine performance or no vibrations. It's usually when I am stopped at a stop light or just parked in gear that the noise is most pernounced. Also when the car was parked on an incline (the front of the car facing upwards) while in park, the car made he calttering noise. But when I went and parked in the opposite direction on the incline (the front of the car on a downward slant) and in park, the clattering noise was non existent or perhaps so low that I couldn't here it. I just don't get it. I am really baffled. Do you know what this could be?

it's a 2000 alero, 2.4L V4

Anyone expalin this one? There is the engine info.

How does the engine look when the noise is at its worse. Is it moving or shaking? Have you checked the engine mounts?

Are you sure it is not drive belt system noise? The A/C clutch can give off a similar sound when the clutch plate air gap is off or it could be the pulley bearing. This is with ac off.

If it was a connecting rod or crankshaft bearing you should hear a knocking sound that changes with rpms.

The noise does no get louder as the RPM increases. Like I mentioned. Once I go put the car into gear. The clattering noise starts. And no thte engine does not shake. The engine runs smoothly. There is no engine roughness or any of that sort. The car has about 158,000 miles on it. I had never changed the tranny fluid. Do you think the tranny can make this noise?

That would be a good starting point, especially since you are only getting the noise while in gear. It is possible the tranny is making the noise. The tranny should have been serviced back at no more than 100K miles. Try getting the ATF replaced and a new screen filter and go from there.

I have a 2001 2.4 Alero with the exact same problem! it has been doing it for 8 months, I have had 5 shops check it out, no one knows. I've replaced plugs, fuel filter, tensioner, belt, and no change. any luck with yours yet?:banghead: