My car was hit and the compression bumper did its job, no damage other than minor scuffing where it compressed in a good few inches, other vehicle (modern plastic SUV) shattered on impact.

My question is are the 'pistons' spent? Is the oil discharged? Not sure how they work but the bumper part moves now where as before...due to age maybe, it didn't budge at all.

As a side note I'm sooo glad I didn't do the bumper trim and pull it in, I wouldn't have a tail end at this point.

 

By design

Spent.

They're not oil filled. It's some odd, plastic-like material, granular in texture, rather loosely packed, design to compress...and not rebound

Cheers
DD

 

I'll take Jaguar plastic over a $2500 bumper any day.

now..onto the fun bit. Fixing the piston function.

 

Vancouver
NOS pistons still come up occasionally on UK ebay, at least.
UK spec cars never had them. We just have a long bolt with a huge washer each end, that fits into the same chassis hole as the pistons do and holds the bumper like that.
It is quite possible, I would think, to find a couple of shock absorbers the same length and use them instead of the OEM pistons.

 

I have a pair of NOS shocks BD48649 for sale cheap.

Rob in Ontario
905-932-0284