BMW Z4 E89 3.Oi 2011 - Water Ingress but no leaks

Hi all, I have finally signed up after months of reading various useful topics surrounding my Z4 on this forum. Various people seem to have had water ingress problems with their E89 but also appear to have gotten to the bottom of it (eventually) – from water from the tail lights, high level brake lights and the rubber seal at the top of the boot lid.

I am having similar problems. Water appears under my battery with no visual indication as to where it is entering the boot. The Z4 has been with BMW a few times whereby the have stripped the boot and carried out extensive tests. Even after pointing them in the direction of some of the problem areas indicated by this forum….still nothing! All checks out, no leaks, seals good and drains clear. My Z4 has also benefitted from the recall indicated by the Green button on the right hinge.

The water is fresh water (not rain water or soapy) which makes me think it appears when washed/ rinsed each time. For instance the timeline since my last bout went as follows:

Returned from BMW 30th March 2016 dry:

1. washed on day of collection by bmw
2. 1st April - rain on trip to Glenrothes and back.
3. 2nd April - hand washed - rinsed, shampooed, rinsed again then dried with a chamois (before I opened boot to check)

...boom water and in it went again!

Currently I have my Z4 back dry as a bone for the past week, still no further forward, awaiting the possible next bout of water appearing. The boot is currently caked in spray powdered chalk under the carpets to indicate any trickle marks that may appear should this happen again. Since its return it has seen heavy rain, hail and has been jet washed (carefully) since and still the boot is dry. I plan to do my usual thorough Saturday hand wash this week so fingers crossed.

BMW have stripped and tried every test imaginable…trust me the tech sat me down and went through a detailed list for 20min after the second time.

Now….this has led me to wonder if I am actually at fault. I have ruled out leaving the boot ajar when washing (I’m not that stupid, especially twice!!) I guess my question is. After washing your E89, do you then lower the roof to clean the interior as I do? Obviously I chamois it dry first but I am wondering in lowering so soon after a wash is allowing trapped water from the hinges, recesses and cracks of the roof to run into the boot by doing this. I need to add that the carpet is always dry. The water appears to get under the carpet and goes to lowest point.

any info appreciated.

Could it be water forced into the brake light on the boot lid when/if you pressure wash ? Just a complete guess though

No they ruled this out when the boot was stripped, as did I as it happened the second time after using a garden hose also. Hence the jet wash when I got it back the other day...no water. I'm hoping just bad luck is at fault.

I know the e85/86 had a issue with water getting in through the tail lights,hope that's the problem here ! Sounds as if you've done the rite thing with the talcam. Good luck finding it

Tail lights ruled out also. its been water tested to the max. In the water bay, under high pressure, low pressure and with standard hose. Left out in heavy rain. Tested on an incline/decline. Arches blasted, deliberately put a heavy flow over drainage areas etc...you name it. They've even taken on board suggestions I sent them from this forum including the seals above the boot-lid. All water tight, so they and I am baffled. had the car for 30hrs odd testing in total... nothing. Declared water tight but did say that I've to take straight back should the problem reoccur and they will follow the water trail from the source created in the spray chalk.

So...this leaves me to believe I maybe doing something wrong when I come to wash it. Does anyone else lower the roof as per my above question when cleaning?

Tape toilet tissue all around the edges of the interior of the boot seal, monitor it.

Great idea!...done! That coupled with the chalk should hopefully identify location should it happen again.

So, update, thoroughly washed the car - rinse, wash, rinse then chamois. Checked sponge under pump dry but couldn't tell if wet to touch or just cold. Popped some kitchen roll under for min or so, pulled it out and bone dry.

Only difference this time is I never put the roof down after. Has anyone else had issues when putting roof down after a wash? Does anyone else put roof down after or clean the interior before washing the exterior?

HI all,

Just an update. I have had my Z4 back from BMW for a month and a half now and I'm happy to say that I have had no issues whatsoever with any water in the boot. The boot is still covered in spray chalk which is still undisturbed by water. I also took Maniac's advice with regards to the toilet tissue test which is still present...again showing no signs of water.

Since getting the Z4 back I have had the roof down almost daily throughout May and June with it seeing torrential rain for most of April...still no issues. I have been washing the car and leaving for 24 hrs before putting the roof down. I also only clean the inside of the car with the roof up now. I fitted a weathertech boot matt for good measure:



I am still mystified as to how the problem occurred in the first place. I can only assume that water gets trapped in the seams of the roof when washing and even after a chamois the car may look dry but a small amount of water must run into the boot from hidden cracks and crevasses as the roof lowers...either that or BMW have disturbed something, for the better, when reassembling. All I know is that, in future, I will never lower the roof unless 100% dry. If its been raining I wait 24hrs before lowering, same after a wash.

A design fault or stupidity? Guess Ill never know. It'd be interesting to know how many other forum members, after excitedly washing their Z4 on a sunny morning, pop their roof down shortly after polishing it up to enjoy the day ahead and drive in the sun.

The green button you talk about, is that it bottom right of your picture.
Because if you look carefully there is a petrol pump symbol moulded in.
When I have had that area apart it appears to go to the petrol flap via a green cord.
I know if I wash my car then raise the boot water runs out from the high level stop lamp onto the rear window, then needs mopping up before I ever open the roof.

I've rarely put the top down after washing, water sits in the many many rubber seals and needs some time to evaporate.

The odd time I've put the roof down wet though hasn't resulted in water other than on the boot trim. I have though, from first buying the car six years ago, put velcro on the part of the boot trim that lifts to reduce knocking over rough ground so perhaps that also helps seal the battery and pump area.

Hope you have finally fixed it.

I do cringe every time i read 'chamois' in your thread.
Seriously ditch it. They are the tool of the devil and will rip your paint to pieces with trapped dust and grit.

Use proper drying cloths and avoid the swirls..

wu_swordsman said:

No they ruled this out when the boot was stripped, as did I as it happened the second time after using a garden hose also. Hence the jet wash when I got it back the other day...no water. I'm hoping just bad luck is at fault.

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Funny this but twice I have had water in the cabin around the top of the windscreen after washing and both times it was using a hose rather than a pressure washer. Never had water inside the car with the pressure washer.
I dont know what the difference is, maybe more water in the one place for a longer time, but thankfully its only done it twice.
Only reason I noticed it was there were a couple of beads of water on the windscreen that wouldnt budge when drying the car on the outside.

Flybobbie - Yeh that's the green button. It is smooth with no symbol on it. Yeh I get that but the water runs away nicely down the water channels an out the drains no prob.

Maniac - I agree. This may have been where I have been at fault however, water never ends up on the boot trim or carpet it just "appears" in the battery compartment with no indication as to where is has come from.

Cj10Jeeper = Ha ha, I was waiting for someone to pick up on this. I guess its down to preference. Used a Chamois on all my cars for 20 years without issue - no light scratches or swirls...even on my black cars. If you've rinsed, washed, rinsed the car thoroughly enough there will be no dirt/dust on the car. Use the two bucket method on the Chamois with warm water in each to ensure nothing trapped before wringing dry. I do this a panel at a time.

Nictrix - Might be worth treating the seals where the roof meets the windscreen just to be on safe side.

Water ingress is a known problem, it comes through because of the rear light seals. BMW updated the part on 2013+ models, but you can get the lights replaced with the updated design for £220/£440.

I had the same problem last summer, found a bit of water in the battery compartment. I have the sDrive23i 2009.

I took the boot to pieces and found a leak on the left side, through the vent that lets out air when you close the lid. I found this laying inside the trunk as a (good) friend poured water on top. This kept dry, but later in the autumn I had another leak, not quick, but the car was stored outside for a month or so, and suddenly I found 5-10 liters of water in the battery compartment. I was just changing tires and washing the car, and while waiting for the cleaning hall, the car complained on low battery, but I charged it a month ago, and haden't used the car. So when I was connecting the charger I felt water...

The vent on the right side was also leak, the rubber seal around the vents are "rotten". Bought new ones at around 20£ for two.

The left one is easy to replace, the right one is pretty tricky as there are a lot of electronics there.

The roof didn't work at first, but started working as I replaced the relays controlling the roof. It was giving an error when opening the roof for a while, but it stopped after a month or two.

When I had my car key read by BMW dealer, they said the rear vents had been changed on call back.
Have yours been changed?

Yes, I have the green tab also to signify that this is the case. its worth noting that since my last post I have had no issue with water in the boot. The problem seems to be resolved. how....? I cant answer that but all is well.

People go on about the green tab, I think you will find it's an emergency fuel cap release.
When you take the rear right tail light off, a same coloured moulded plastic cable runs around from it to the fuel flap.

Would appear to be quite standard on other models.
I would have the key read.

wu_swordsman said:

No they ruled this out when the boot was stripped, as did I as it happened the second time after using a garden hose also. Hence the jet wash when I got it back the other day...no water. I'm hoping just bad luck is at fault.

Click to expand...

Have you had any issues since? I'm wondering if jetwashing the rear wheels/inside the arches contributed to the problem?

Dear All

Hi - I'm new to the forum and sad to say starting with a problem...

We've just taken delivery of a 35is after about 4.5 years running a 2.0is.

Anyhow, I was shocked to find quite a lot of water in the battery well and in a pool in that conical tubular hole in the foam to the right of the roof pump. I must have removed nearly half a litre so far. The water is clean and tasteless and possibly had some detergent in it as I noted slight foaming when wringing out the kitchen paper I've been using to mop it up.

It been raining really hard since the car arrived so I don't know if it is rain water getting through somewhere, or possibly its from being pressure cleaned by the garage we bought it from.

I have checked the carpets on both sides inside the cabin and both are perfectly dry. So I think the cabin is water-tight at least.

Looking in the battery well, there is no water staining or corrosion that I can see - so if I had to guess, I'd say it was recent water, rather than water that had been there for a long time.

I guess my first question is should I simply start by trying to remove all the water and checking it each day or do I need to go straight to a garage to have something replaced / cleaned - maybe a rubber seal, drain hole or vent (I've had a brief read of this thread)?

Kind Regards to All