Water in the boot - HELP!!

[Worcester_spoon]

Ok, so I'm reaching the point of madness here. Been chasing a leak around the boot for about 2 months. Refitted the lights (they're new anyway, so seals should be ok) and have had the carpets out and a dehumidifier in, but still getting a leak (along the top line of the plastic battery case in the below picture).

I 'think' I've narrowed it down to an ill fitting 3rd brake light as there is definitely daylight between the seal and the metal on both corners, but I can't believe this small gap would let in that much water.

Why I need help...

1) is there anything else I'm missing here that it could possibly be other than the 3rd brake light (lights refitted, drains cleared 12 months ago and bungs removed)?

2) given I'm on my 3rd genuine BMW brake light, I'm assuming it's an issue with the shape of the hole rather than the part itself, so any suggestions for combating this other than some carefully and finely applied silicon around the light itself?



Stu

 

[firebobby]

I was right about the brake light then :wink:
Did you have it fitted by a dealer, if so take it back and let them deal with it.

 

[Worcester_spoon]

I was right about the brake light then :wink:
Did you have it fitted by a dealer, if so take it back and let them deal with it.

Yeah, it's been the brake light for a while (hence the 3rd one I'm on as I assumed it was a bad part!) - I just couldn't believe such a small hole could let in so much water, so I've been chasing something else.

Appears as though it can't be anything else though, so it's now just finding a solution as the current light is 3 weeks old and has a perfect seal and yet there is still daylight between it and the body work.

Do I seal the light in place (thin line is sealant between light and bodywork) or take it out and form a sealant band around the hole and fit the light onto that, a bit like a flood defence?!?

Fun. Not.

 

[firebobby]

I used a small bead of black sealant to seal my brake light

 

[Worcester_spoon]

On the body before fitting, on the back of the light before fitting, or once fitted (so I between the gap)?

 

[Paulj100]

I have the same problem after heavy rain I had water coming into the boot on both sides! Further investigation I found that on the passenger side rear light cluster the Orange indicator plastic circle had a tiny crack replaced the light unit and no more water on that side. I still get water on the other side and that light unit is perfect but noticed the third brake light has a crack in that so I'm guessing this is where the water is still getting in. Hopefully replacing that will finally cure the soggy boot.



Paul

 

[firebobby]

I put it on the seal then carefully fitted it

 

[MACK]

you are not over tighten the bolts for the lights are you? just wondering why your going through so many rear brake lights they dont like to be overly tight

 

[Number5]

I'd run a bead of clear sealant around it before I push it back tight.

Unfortunately that's about the best advice I can give, as mine never gets wet, so not a problem I've had sorry.

 

[Worcester_spoon]

you are not over tighten the bolts for the lights are you? just wondering why your going through so many rear brake lights they dont like to be overly tight

If I could tighten them more I would - seal never reaches the bodywork sadly!

 

[Worcester_spoon]

I put it on the seal then carefully fitted it

I's run a bead of clear sealant around it before I push it back tight..

Thanks all - this is where I'd got too so at least we all seem to be thinking the same way...

Let's hope it's dry enough tomorrow to give it a go.

 

[MACK]

you are not over tighten the bolts for the lights are you? just wondering why your going through so many rear brake lights they dont like to be overly tight

If I could tighten them more I would - seal never reaches the bodywork sadly!

The issue these usually have is being over tightened on the springs that go on the bolts when the nuts are done up too tight. the light unit then has a habit of cracking when you shut the boot.
You seem to basically be having the opposite to this, when you take the light out the tailgate metal work, including where the lamp bolts go through is straight and true (hasnt been bumped etc)
I'm really just struggling to understand why your doesn't seem to tighten enough

 

[Worcester_spoon]

I'm really just struggling to understand why your doesn't seem to tighten enough

You an me both! I can only deduce that, for some unknown reason, the hole where the light fits has been deformed by something. The previous owner had to replace the light just before I bought it (but never any mention of a water leak) so I wonder if it was deformed at this point, as it was being taken out?

Anyway, hopefully the sealant idea will do the trick and I can stop worrying about the rain agin

 

[MACK]

I'm really just struggling to understand why your doesn't seem to tighten enough

You an me both! I can only deduce that, for some unknown reason, the hole where the light fits has been deformed by something. The previous owner had to replace the light just before I bought it (but never any mention of a water leak) so I wonder if it was deformed at this point, as thought was taken out?

Anyway, hopefully the sealant idea will do the trick and I can stop worrying about the rain agin

might be worth seeing if a forum member has a decent shot of a boot lid with the light out to compare with yours. the obvious thing here would be if the previous owner has pulled the metal work the light fits into and you might be able to simply bend it back ending your wows and happy days

 

[Worcester_spoon]

Good shout - my mate has my old Z4, so i'll get home to bring it round and take a look.

 

[Rich8]

You certain the leak is from the brake light?
Sure I've seen a few old posts on here about a vent that is in the back somewhere near the rear lights which a couple of people have had leak on them and needed to be re-seated or re-sealed.
I've not looked for it in mine as never had the problem so can't help much as to exactly where it is, but from what I remember it was in the boot near the main light clusters, I think behind some carpet or trim and I think leads out to somewhere behind the rear bumper cover.
Can't remember if the solution needed rear bumper cover removing or could be sorted from in the boot.
Search on here should turn it up.

 

[Rich8]

http://www.z4-forum.com/forum/viewtopic.php?f=3&t=61611&hilit=Leaking+vent+in+boot

this post is the one I'm thinking of

 

[Worcester_spoon]

http://www.z4-forum.com/forum/viewtopic.php?f=3&t=61611&hilit=Leaking+vent+in+boot

this post is the one I'm thinking of

Thanks Rich - there's definitely water coming in through the brake light, but still seems too much to me for such a small hole, so maybe the vents as playing a part too. I'll get some new ones on order asap and get them replaced.

Right now, I'll try pretty much anything to stop the swimming pool in my boot :x

 

[A320_phill]

Mine was the vents on my coupe. The foam seal had failed and was very dirty so I unclipped them and ran a bead of silicone around the seal and reinstalled. Really easy once you get the trim off around the rear lights which can be a pain! You don't need to take the bumper off.

Touch wood the boot has been dry for 18 months!