Xantia Knocking Noise {!}

[captainalice]

In the words of an infamous ex celebrity...I know...its a knocking noise from the front,central, whenever encountering even the smallest bump. Its not droplinks and its not any of the usual suspects. I am told it could be the bolts which fix the rear subframe to the front,and that these loosening is a common problem ( the car is a 1999 Hdi hatchback,145 k ). Before I jack the car up,in the wet,take off the undertray,crawl underneath...is this likely ? Where would I find these bolts which have dared to loosen ?
Thanks in advance for any advice
Dave

[CitroJim]

Welcome to the forum Dave

What 'usual suspects' have you already checked and eliminated?

There's no bolts that fix the rear subframe to the front... Both subframes are independently bolted to the body monocoque with no connection, except the bodyshell itself, between them. I've known the rear subframe rubber mounts fail, both front and rear, but it's not common and you'd hear the noise toward the rear although it's possible a failed rear subframe front mount might possibly sound like it's coming more from the front of the car or toward the middle.

The knocks could be slightly loose steering rack securing bolts. I've known that once or twice. Parts of the rack are very close to the body and it does not take a lot of looseness to set up some banging noises!

Once the checked 'usual suspects' you've eliminated are known we'll be better places to advise...

[Stickyfinger]

front,central (or could sound like the front central)..........things that could "knock" over bumps

Exhaust, failed hanger ?
Steering ram bush
Steering rack bolts
Control arm rear bushes
DROP LINKS
Failing Strut tops