Battery submerged in water

Every year there are heavy rains my battery compartment gets flooded with water. The first 2 years this happened I took it to my moms friend who is familiar with BMW's but he obviously didn't fix the source of the problem. I called my favorite service writer at Stevens Creek BMW and knew right off the top of her head that it was probably the sunroof drain either clogged or broken causing the water to pool there.

My question is should I go to my moms friend who charges usually $300 to $500 which I can afford or gamble and take it to the dealership which I might not be able to afford?

On my E39 there were drains located on both the front and back of the sunroof rails. I assume the E60 is pretty similar, but I haven't checked mine out to know for sure. I used about 10 feet of heavier duty weed wacker line to unclog the blockage (leaf and dirt debris). The front were pretty easy to get the line into, but the back took a flashlight and extra effort to get the line into the drain. Eventually you could hear the line hitting the plastic molding on the inside of my front fenders and rear quarter panels, which means the blockage was cleared. However, if your sunroof seal is bad you should probably replace that too because even if the drains are unclogged they can't handle all the water caused by a leaky seal. On the E39 the water would drip into the front A pillars and rear C pillars. If it's only dripping in the battery compartment there may be a crack or issue with the drain line. From what I remember the line ran through the battery compartment.

If you ask me it actually sounds like the trunk weather stripping is bad, but without seeing it I couldn't tell you.

Long story short, regardless of who you take it to, you should look at it yourself to see if there are any glaring issues like a cracked drain line in the battery area. Then you can figure out the best person to take it to.

if u have water in the battery compartment. check under the spare tire. make sure there is no water in there.. and relocate the electrical parts . like as soon as possible to avoid a much larger problem like frying ur electrical componants..and cost several thousands to repair I just moved mine last weekend into the side trunk panels.. cant urge u enough to get done A.S.A.P

Originally Posted by H F

if u have water in the battery compartment. check under the spare tire. make sure there is no water in there.. and relocate the electrical parts . like as soon as possible to avoid a much larger problem like frying ur electrical componants..and cost several thousands to repair I just moved mine last weekend into the side trunk panels.. cant urge u enough to get done A.S.A.P

I second that. I am considering moving them into the panels myself. How hard was it?

Piece of cake, really easy

Also make sure that its not leaking through your right taillight. Mine would get a pretty decent amount of water into the battery compartment every time it rained. It was the taillight (seal, gasket, weather strip) whatever it's called.