The definitive guide to Z4 E85 rainwater leaks

[theosinc930]

The definitive guide to Z4 E85 rainwater leaks. I've had quite a lot of problems with leaks, so here are all the weakspots I found and fixed.

I think it should be self explanatory that the first step is to clean out those rainwater drains from the soft top, where the roof pump sits, but I think any E85 owner knows that by now
There are a million tutorials on YouTube on how to do it, so let's not waste time explaining it again.

The second potential problem area are the rainwater drains at the windshield cowl, where a lot of leaves like to accumulate. So it's also important to clean those out. Ideally you could remove the entire windshield cowl for cleaning, but there is quite a risk of breaking plastic clips. So I would recommend ordering new ones before taking it apart.


The third problem area are the vapour barriers in the doors. If you notice wet carpets around the door sills, that's gonna be your problem. You have to take the door panels off, replace the vapour barriers with new original parts (they're not expensive) and seal them up with butyl tape. Again, I'd recommend having new plastic clips on hand before taking the door panels off. Part numbers for the left and right vapour barriers: 51487016655, 51487016656

There are three spots where the E85 has boot leaks:

The screws on the taillight trim - take them out, put some silicone in the holes and put the screws back in. Putting silicone in the screw hole that's the highest up (the one next to the boot strut) should be enough. The rest can just be tightened.



The side vents behind the carpet- they have rubber seals on them that go bad after 20 years. Replace them with new original parts, they are cheap and easy to replace by unclipping the carpet on the side walls of the trunk. Part number: 64226909340



The center brake light gasket. Sadly you have to replace the whole light to get a new gasket. I got an aftermarket one and it's just fine. The original one isn't in stock anymore...

Even if you think you don't have water leaks on your E85, I'd still recommend leaving it parked in some decent rain and checking all of the carpets inside the car. My car usually sits in the garage, so I didn't know I had leaks until I left it outside.

Took me a lot of time and frustration to find these things.... but now I have a bone dry car, even in strong rain.

 

[enuff_zed]

Excellent!
I would make one small amendment based on personal experience.
The butyl tape is rubbish; it lifts away at the bottom of the door where the metal kinks inwards. Far better to use a sealant like Tec7.
But each to their own.

 

[theosinc930]

Excellent!
I would make one small amendment based on personal experience.
The butyl tape is rubbish; it lifts away at the bottom of the door where the metal kinks inwards. Far better to use a sealant like Tec7.
But each to their own.

Good to know. I just used what the factory used.

 

[Zedebee]

Even if you think you don't have water leaks on your E85, I'd still recommend leaving it parked in the garage

Fixed that for you

Seriously, good write up, I think you covered all the common issues.

 

[caius]

The center brake light gasket. Sadly you have to replace the whole light to get a new gasket. I got an aftermarket one and it's just fine. The original one isn't in stock anymore...

I've fixed this with a thin layer of sealant round the light where the gasket had failed. Makes removing it in future a little more difficult but works well to seal it.

 

[AL_MO]

The main leak I found was due to a poorly fitting windscreen scuttle following Autoglass’s bodge screen replacement. The water run down into the engine bay, through a tiny gap in the bulk head, and into the passenger side footwell.

I’m going to look into best long term fixes for this once the weather gets better.

 

[TriggerFish]

Excellent!
I would make one small amendment based on personal experience.
The butyl tape is rubbish; it lifts away at the bottom of the door where the metal kinks inwards. Far better to use a sealant like Tec7.
But each to their own.

Interesting - I've just replaced both my door seals and used new butyl tape (all torn up). I've tested it for watertightness and it is all dry/not leaking. Have you found that the tape fails over time? Cos if so, I've got some automotive sealer I can use in addition before refitting the door cards...

 

[enuff_zed]

Interesting - I've just replaced both my door seals and used new butyl tape (all torn up). I've tested it for watertightness and it is all dry/not leaking. Have you found that the tape fails over time? Cos if so, I've got some automotive sealer I can use in addition before refitting the door cards...

My personal experience; and allowing for the fact there are several brands of butyl tape; is that after a few weeks the bit at the bottom near the front edge starts to lift again.
As I say, I may have got a duff roll of tape, but @bigwinn suggested Tec7 and I haven't looked back since.

 

[TriggerFish]

Understood, thanks! I'll go and add a bead of sealant in addition to the tape as a backup. Luckily, there's enough of a skirt between the tape and the edge of the vapour barrier to add sealant without disrupting the tape.

 

[Joez4]

I did mine with tec 7 on a forum recommendation and also highly recommend it, my original membrane would leak slightly where the door bows in near the hinge despite how much butyl tape I used in that area.

Still tho i had water ocassionly getting in, turned out to be the weather strip on the door, if it collects water on the strip by one of those drain holes like mine did then chances are its not sealing properly, I changed mine for a used one in good condition and I haven't had water in the car since.

Notice how someone replaced my membrane at some point in the cars life and just put it over the airbag