When driving through puddles of water, slush or snow, the exhaust may cool down fast enough to change shape and touch the propeller shaft, causing a high pitched squealing noise. this noise will be noticed by the driver for only a short time; once the exhaust temperature equalizes the noise will disappear. this creates a high-pitched, siren like noise, which can scare the driver causing his/her to swerve or lose control of the vehicle. the is a design defect recognized by volvo with repair kit available pn# 30742265. as this is a design defect and a serious safety issue, this should be recalled by volvo and not a $250.00 repair by the customer. *tr