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first post here. My car , Chevy Malibu 2005 LS 3.5L V6, recently started to be much more loud when accelerating. It shake a lot too. But only when accelerating and especially at 1000RPM. When don't move its smooth. But after some times, I heard a small pitch sound, like birds or grasshopper. So I suspected it was my water pump, but the pitched sound seems to be every now and then. So suspect it could be the exhaust. Any idea?

I hope I can repair it myself, because I don't really trust mechanics honesty. I got the car to two different mechanics last year, one said everything was okay for general inspection, the other said I got something with my brake oil.

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  • I used an OBDII, and got no codes. I have no light on the dashboard. Commented May 10, 2018 at 22:25
  • Welcome to Motor Vehicle Maintenance & Repair! Commented May 10, 2018 at 23:30

3 Answers 3

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Check the tension and condition of your belts as they might need replacing or adjusting. If you had a recording of the pitch, it would help us diagnose.

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The exhaust system might be vibrating against the body structure of the car, particularly at 1000 rpm. Check the exhaust system hangers and rubber mounts for wear or fracture. You should make sure that the exhaust system can move, but cannot come in contact with the metal underside of the vehicle.

Note too that worn motor mounts might, at certain rpms, allow the engine to move sufficiently that the exhaust touches the body structure.

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Undue vibration under acceleration is often caused by worn motor/engine mounts. A quick and easy way to diagnose this to watch the engine: Open the hood, start the engine, watch the engine and have somebody else rev it (Obviously park the car and put in in neutral first ;-) ).

The engine should not attempt to jump out: A little movement is fine, but not excessively (should not move more than an inch, maybe a centimeter at most).

While comparably easy to fix, it's not cheap as the engine often needs to be removed to replace the engine mounts. This takes a lot of time.

The high-pitch noises are often caused by worn belts.

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