Water Leak in Boot / Trunk

[PhilW2]

Hi I have just bought a 2014 Z4, love the car but have discovered wetness in the battery area and the foam around the roof pump is soaked, I understand this is a normal problem, but I've stripped it all out today dried, and am looking for the source, but I've come across a problem I can't find any info on.

There was water under my roof pump and battery, but when I dried out the body work is in good condition, however to the right of the battery (as you look from the open boot) there is a battery positive joint post and a hole where a power cable goes outside to something under a piece of trim (I've attached a photo), there is a very slight rebate in the boot floor, that these 2 sit in, and the metal here is rotten to the point I can push a screwdriver through to the outside quite easily.

The rest of the boot floor is in perfect condition only the rebate that has the batt positive joint and the power cable hole showing any corrosion

Anyone had this?

I'm wondering if this is an entry point for water, or just somewhere it has sat and corroded, which if it is would be strange as the rest of the boot floor is perfect, other than this very localised corrosion

Apologies if there is a thread on this, I can't find it.

 

[B21]

Boot vents, rear light seals, roof trim drains are you're normal 3 issues

 

[PhilW2]

Thanks, im working through those, its the localised corrosion I'm trying to understand, im surprised to see a spot in the boot floor that has deteriorated to the point of perforation when everywhere else (including where the water has been obviously sitting) looks perfect. It's strange, and can't find anyone else mentioning it.

 

[B21]

Looks like long standing water / corrosion around a grommet..

Like all issues there's a range of problem from fresh water to really bad corrosion depending on many factors..time / temp / electrolytic corrosion etc

 

[dyonisis]

Hi,

I am also tackling an annoying leak in the boot (suprise, suprise!). I have correctly attached rear light gaskets and sealed, both sides were a mess. Reapplied sealant to boot seal and corner peices (corner bits with two torx screws), I have a couple of new boot vents on the way, though mine appear to have been changed during the recall. I can't actually see any evidence of ingress on these but as I have a 2009 car I thought even the recall version could fail over time. I checked the boot this morning and it was dry even after heavy rain the last couple of days. I emptied a watering can over the rear window and no evidence of ingress. It's a dry day so took the car out then checked again, water in the battery well and side bits under lights Arrgghhh!!. I believe water can be retained in the chassis rails, so I'm hoping I have fixed the leak and the water will eventually dry up, empty.

My question is, I have wrapped the foam motor shell in a thick bin bag and waterprrof taped around it to make it snug but I have noticed water can splash over the edge into the bit where the motror sits, would I be ok to wrap a bin bag around the motor itself, or is this a no no?

 

[B21]

Hi,

I am also tackling an annoying leak in the boot (suprise, suprise!). I have correctly attached rear light gaskets and sealed, both sides were a mess. Reapplied sealant to boot seal and corner peices (corner bits with two torx screws), I have a couple of new boot vents on the way, though mine appear to have been changed during the recall. I can't actually see any evidence of ingress on these but as I have a 2009 car I thought even the recall version could fail over time. I checked the boot this morning and it was dry even after heavy rain the last couple of days. I emptied a watering can over the rear window and no evidence of ingress. It's a dry day so took the car out then checked again, water in the battery well and side bits under lights Arrgghhh!!. I believe water can be retained in the chassis rails, so I'm hoping I have fixed the leak and the water will eventually dry up, empty.

My question is, I have wrapped the foam motor shell in a thick bin bag and waterprrof taped around it to make it snug but I have noticed water can splash over the edge into the bit where the motror sits, would I be ok to wrap a bin bag around the motor itself, or is this a no no?

The motor can run warm so make sure its a high temp bin bag!

 

[PhilW2]

I've got rid of the foam support at the minute (because it smells really bad, and can smell it through the car!) I've ordered another, but as a temporary fix I've packed the motor assembly in old towels which I check every few days.its easy enough to lift out the assembly and put towels in. If they are damp when I check them, I'll swap them, wash and repeat. When im confident I've sorted leak I'll fit the new foam. Not done anything with plastic bags yet, but am thinking about something similar in future when I put the proper foam back.

 

[flybobbie]

Leave battery cover off and surround with some kitchen tissue or loo paper.
See where it gets wet first.
Once found a weld pin hole leak on a Chevette windshield frame using this method..