Have Volvo Questions? Ask a Volvo Mechanic for Answers ASAP
Hi im kevin sre you using parking brake when parked up ?
Ok that rules that out so you just get one knock when you pull away or over bumps ?
Ok so only happens when reversing .does it matter if your turning or going straight ?
To be honest there isnt alot this could be its a strange one and isnt a common complaint or a common issue .the fact it only happens when pulling away is odd and would most likely point to a bad cv on that side but you would normally get that in forward also .its unlikely to be suspension related either as you would expect this noise to occur when moving .i suspect most likely cause is the cv
On your drivetrain you have something called a drive shaft and at either end it has a constant valocity joint .these allow drive to the wheels and still allow movement up and down on suspension .these joints are packed with greece and have a rubber boot around them to keep greece in and dirt out .ober time the greece can break down and wear in joint can occur normally resulting in a knocking noise when pulling away