wen my engine is at is first fired up it makes a knocking noise similar to that of a bearing coming from the rear of the engine\transmission area but wen it is given revs or warms up to idle the noise stops at 1st i thought it may be the exhaust is loose an hitting on something but cannot find anything hitting anywhere is there any common faults or anything anyones knows frm experience that it might be

If its not broke it will be soon