BMW E91 LCI - Water in battery compartment

BMW E91 LCI - Water in battery compartment

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Jay_87

Original Poster:

997 posts

169 months

Monday 12th October 2020
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So following on from my battery issue where I thought it was discharged and struggling to start the car I went to fit my CTEK charger on and give it a little boost over the weekend.

I took all the panels out and noticed a pool of water in the bottom of the batter tray, around 30mm deep, I have no idea where the water has come from, there are no obvious signs of damp or water ingress where I would expect it, all the trim and sound deadening was dry to the touch.

I also noticed that the positive side of the battery cables have corroded where they drop down behind the battery... I suspect this where the issues is coming from ref the slow the starting.

Not being able to find or remove a bung to release the water I had to drill small hole in the floor of the car, I've protected the area with some rust proofing.
(I also own a Ford so have a lot of that in the garage) Which will allow any further water to escape.

My main concerns are now two fold.

Damage to the battery cables, I'm wondering if I can clean them up and protect them better rather than having to shell out for new from BMW and secondly where is the water coming from!!

Does anyone know of any common faults with the touring or saloon? Most of what I've found has been in relation to the E93 convertible.

I was reluctant to disconnect the battery at the weekend for fear of losing any coding on the car but if I can get a process in place to prevent that then its something I'm happy to tackle on my own.

twokcc

589 posts

142 months

Monday 12th October 2020
quotequote all
Jay_87 said:
I also noticed that the positive side of the battery cables have corroded where they drop down behind the battery... I suspect this where the issues is coming from ref the slow the starting.

.
Had the same problem with my 2009 E91 but battery well was full to top. Took battery and syphoned water out. Battery connection is a myriad of wires and can only move the very large positive connector to one side because of the wire mentioned above. Mine heavily corroded and after moving it a few time it broke where it goes through to the underside of the wheel arch. Had to have it relayed to local BMW specialist and they repaired it and refitted battery. So battery was completely disconnected and seem to recall lost some minor settings of info on idrive but nothing serious..
Same as you couldn't find any drain holes or where water had come from. Not filled up since some presume garage unblocked/drilled drain holes. I had fitted new rear door gas struts not long before but don't think that caused the leak.

helix402

6,141 posts

147 months

Monday 12th October 2020
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Check side vents behind the rear bumper.

beambeam1

278 posts

8 months

Monday 12th October 2020
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I had this on my first E91. The hose to rear windscreen washer had disconnected. I will post some images:

https://flic.kr/p/EP7uVq
https://flic.kr/p/EPacHU
https://flic.kr/p/HZZ6Mg

In that last image, above the battery you will see some black carpet/trim. It resides amongst a clutch of wires and cables but will be easy spotted if you have these images for reference.

I have a dog and can only imagine the frequent opening and closing of the boot is somehow what caused it. I removed the battery and dried it up with blue paper towels and a hair dryer. I cleaned the terminals wipes and blue towel again then reconnected everything back up. Didn't have any more issues for the remaining three years of ownership.

Sorry if images are massive, I'm linking from my iPhone.

Edited by beambeam1 on Monday 12th October 17:56


Edited by beambeam1 on Monday 12th October 17:57

Jay_87

Original Poster:

997 posts

169 months

Tuesday 13th October 2020
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Thanks guys & Thanks for those pictures - I think this might be my issue as I can see anywhere obvious that it has been coming in, im going to check that pipe asap!

I too have a dog and he's in and out of the car quite frequently, I'm wondering if something similar has happened now, maybe not completely disconnected but has come loose and is leaking.

The water in those pictures was ALOT more than what I had in mine

@beambeam1 did you managed to repair/replace the damaged wires?

beambeam1

278 posts

8 months

Tuesday 13th October 2020
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I didn't have to, cleaned all connections and connected it back up. Was fine and the hose split never happened again.

How did you get on?

Jay_87

Original Poster:

997 posts

169 months

Wednesday 14th October 2020
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Haven't had chance to get back in there yet, its looking like Sunday work now, will update though once I've done it.

What settings did you loose on the car after disconnecting the battery? Did you have to have any coding done afterwards?

b14

700 posts

153 months

Wednesday 14th October 2020
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Does it have a sunroof? If it's like the E61 then they had problems with blocked drains for the rear of the panoramic sunroof that could cause flooding in the battery compartment and various other important parts of the boot that contain control modules.

320d is all you need

2,072 posts

8 months

Wednesday 14th October 2020
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Could be a couple of things

Rear light seals (I think they are a "problem" on the E series BMW)
Sunroof / Roof drains
Rear wash wipe leak

Best bet would be to fully remove the rear seats and all of the side trim (takes approx 30-45 minutes, plenty of DIY guides as well on Youtube) and see if you can trace the water. (Very hard).


Jay_87

Original Poster:

997 posts

169 months

Thursday 15th October 2020
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No sunroof and the rear light seals are good... I think and hope its the rear wash wipe pipe, I'll be having a look in that area again this weekend.