What is it?

[Johnnojack]

Underneath the Golf (1.9 diesel) below the drivers seat there is an aluminium cooler thingy so what is it and what does it do. Also my mate has a manual Golf and his has one too so not for the DSG gearbox. He has pranged his a little on a rock so when it leaks will he stop?

[spiff]

is it covered in styrofoam ? it's not your bluetooth unit is it?
not sure about what you mean when you say, "when it leaks". does it leak, is there liquid.. or do you just think it might leak because it looks like it might be something that contains liquid?

[phaeton]

Is this what your talking about?

[benough]

It's the heatsink for the cooler for the the return fuel line.

Mine's got a ding in it too, has for years.

[Johnnojack]

Spot on Phaeton that's the one. Wow thats a seriously large cooler for fuel. Thanks Ben, so if my mate puts a hole in his Caddy (not Golf) one then he loses all his diesel. I'll give him the heads up on that ta. It is fairly solid though I must admit, needs to be too, being used as an underbody protection device.

[Umai Naa!!]

I've seen the odd caved-in one from when customers thought the Golf would be perfect for doing all the same farm duties a 4WD ute would typically struggle with. Never seen a leaking, though.