Vibration / noise at 850rpm.. Engine mount fail?

[KarlCaudwell Junior Member Find all posts View Profile Close KarlCaudwell]

When the car is at idle it sits on 600rpm the car is nice and quiet. When the aircon kicks in it takes rpm up to about 850rpm and that's when this noise / vibration starts and sound rough. The mechanic says it either the air con compressor or the engine mounts, more likely the latter. Got some people saying they had a similar thing happening and that it was the joint in the exhaust under drivers door and tightening / lubricating this joint made it go away. I have tried that to no avail.

Any ideas? The car has done 85,000km could the engine mounts be stuffed?

[Early Member Find all posts View Profile Close Early]

For an Auto, lift the bonnet up, turn the car on and have a look at your engine when you change gears. In P and N the engine should stay still besdes idling vibrations, but if it moves more than 3cm when shifting to D and R, check engine mounts for visible tears or cracks.
Another way to checking is to put a light duty jack under an engine and gently jack it up just to see if the engine mounts are still holding on or let go.

Or, could simply be loose exhaust or the heat shielding vibrating on the exhaust. Loose bash plates/underbody armour have similar noises.