I have a berlingo 1.9d van and the exhaust knocks when going through puddles and when raining heavily. i suspect exhaust hangers get lubricated with water and allow exhaust to slide from left to right. Strange!
Ron CNC
October 2010
I have a multispace which had a loud knock when hitting small potholes & drain covers etc. After poking about the track rod ends had a bit of play. Changed the pair for about £20 and the knock disappeared. Mine had 70,000 miles and was 6 years old, 1 track rod end had no grease, was full of rusty water and pitted heavily.
divingscubaboy
October 2010
it could be worn CV joints or faulty shock absorbers
GHOST
October 2010
could be anti-roll bar links worn or lower arm bushes worn.