Spare wheel well - another rust-prone location?

[cmdrfire]

Just had a complete clearout of my car, including (for the first time in ages - probably a good year and a half) the boot liner, boot floor, and spare wheel out. Found a good 30-40mm of water in the spare wheel well  Some rust forming as well, though at this point it all looks like surface rust with no deep penetration.

Spare wheel well by CmdrFire, on Flickr

I've mopped it all out, and have left it all open for now to allow it to dry out whatever's left. Next week I'll go over it with a wire brush and see how deep it penetrates; if it's not too deep and it's only slight pitting then I'll POR-15 it all and won't have to worry about it again.

Not sure if this is common on Mk5s (people probably don't check that area too often) or if it's because of the OEM plastic boot liner I've been using since I got the car but some others with older cars may want to have a look (and I'm going to stop using that boot liner - the actual boot floor was damp to the touch when I removed it, so it could be the boot liner was the cause).

[182_blue]

Have you got a reverse camera

[cmdrfire]

Nope. I don't think it's from the hatch, in any case...

[MAT ED30]

rear lights

[cmdrfire]

That's poss, especially as I have replaced the rear lamps with the LED clusters. I will investigate more during tomorrow's daylight... wish I had a garage 

[stealthwolf]

I'm sure this has been mentioned previously but can't remember the cause.

[stealthwolf]

http://www.mk5golfgti.co.uk/forum/index.php?topic=17225.0
http://www.mk5golfgti.co.uk/forum/index.php?topic=18769.0

[MAT ED30]

also check you rear washer tube like on the mk4 it use to split in the headlining and leak down

[Jack Frost]

It'll be the vent hidden by the rear bumper. I also had surface rust on mine. Open the boot and pull back the carpet then pour some water over the rear light and watch it come into the boot.

Cleaned mine up and sprayed with clear Wax.

Part is only about £8 if I remember correctly + whatever labour charges.

[stealthwolf]

Where is this vent and how do you access it?

[cmdrfire]

Thanks guys. I'll investigate this vent tomorrow. I'm going to book into VW next week for an oil/dsg fluid change and a compression check (  ) next week anyway so might get this sorted out while I'm there...

[Snoopy]

I cannot see it that well but are you sure its not just rust off the spare wheel thats stained the wheel well paint due to it sitting in the water?
Saying that the lack of paint on VWs it would not suprise me if the floors rusted

[apollo13]

Where is this vent and how do you access it?

There is on one each side of the car AFAIK under the rear light and round a bit towards the filler cap.

You access them by removing the rear bumper, which in turn is accessed by removing the rear light clusters.

[the bruce]

That's poss, especially as I have replaced the rear lamps with the LED clusters.
I will investigate more during tomorrow's daylight... wish I had a garage 

Do so !! 

And watch if the rust is just on the surface (from the steel spare wheel).

[cmdrfire]

I don't think the rust is from the spare wheel, as it's in a couple of locations not contacted by the wheel, but my wire brush is at work (where my Karmann Ghia is stored) so will have to wait 'til next week to confirm... but it does look like only surface rust so cleaned and POR-15'd quite easily.

Cheers to all for the info on these bumper vent things... I can remove the rear light clusters easily enough tomorrow so might have a look there. If this is the cause I might use some silicone sealant to prevent further liquid ingress.