Replacing Hydraulic Pump

[SpecialNick]

Hi Guys,
You may remember I posted about a leak I was having in my boot well last year: viewtopic.php?f=45&t=61309 (sorry for not posting an update).
After extensive drying the motor worked again, I wasn't able to trace where the water was getting in, but it seemed to stop coming in in such huge quantities.
After keeping an eye on it for many months all seemed fine, until the nice weather reappeared over the last few weeks and I tried the roof; the water was back with a vengeance, and has completely corroded the connections to the wiring harness (fell apart in my hands), and possibly the pump itself.

As it was in for a service today, I asked them to take a look at it to see what work would be needed, and was quoted £2700 for a new wiring harness (£20 on ebay), pump (used £250 ebay), relays and fuses (pennies - although I've tested both relays and they work fine, fuses ok too). Obviously there is labour, expertise and a degree of security in the cost, but I just can't justify spending that sum on what should be a straightforward swapout - which brings me to my question:

My intention is to replace the wiring harness, see if the pump works, and if not replace the pump. Is this a straightforward job? Does anyone have any guidance? My main concern would be refilling the pump properly with hydraulic fluid afterwards (I'm pretty handy but not done much with hydraulic systems before).

[Maniac]

I thin you might struggle with advice on this as you are the only person I've ever read that's had the issue. Have you found the reason for the water if it's happened again?

[SpecialNick]

I did find the source, see attached images. The water only got in after a significant downpour, explaining why it was so difficult to detect (2 BMW mechanics said I definitely didn't have a leak..!), through the seal joint with the two screws in the first picture. Once the water penetrated through the joint, it found its way to the bottom of the well down one of the electrical cables, causing the connectors to corrode and water to get to the motor. Again the fact that it only occurs after a particularly heavy downpour lulled me into a false sense of security, i.e. I would check after light rain and no water seemed to be getting in, making me think the problem had gone away.

I've ordered a used pump from eBay from a scrapped '14 plate (the BMW electronic catalogue says the newer pump is slightly different - has 4 outlets instead of 3 - but that they are backward-compatible).

Images: http://1drv.ms/1AaKFSC

[Maniac]

Those pictures I feel will save a lot of people hassle going forwards. I've just checked that same seal. Mine does not seal entirely either on that side. I also have water after a downpour today, on the wrong side (interior) of that seal. The passenger side seems fine. So, you've located an issue for me also, thank you, I'll be certain to apply some sealant there this weekend. There's no sign of any water ingress to the boot itself, but, there is water on the lower seal that the one you show removed sits upon. Only on the drivers side.

I do find your last pic interesting, the one where you are holding the top seal. This has some sort of paste applied under it, which makes me wonder if they knew the seals weren't right at the factory and they've used paste just in case. I also wonder how such a small leak could have resulted in the entire boot sub section filling up to the point its reached the motor, which stands on stilts to prevent such issues.

[Tricky Dicky]

We've had a extensive downpour today and I've checked the battery well ,dry as a bone , I've not taken off the trim covering over the area you removed ,but it all seems dry at the point were the trim meets the area were your photo showed a pool of water , the trim would be damp if this were so, but as the batt well is dry I think I'm ok ,our car is a March 2013 car if it's of any use

[Angie4m]

Well I've been to check my car. Been chucking it down all day. I have no water around that seal. The only water that was there was after I lifted the boot up and watched it run down to it. Seems that the seal around the boot is doing its job. Had a look from the underside and along the wiring harness and no water. I'll remove the trim at the weekend if the weathers alright but looks like at the moment but it's definitely one to watch.

Just out of curiosity, do you have a warranty at all?

[Maniac]

Well I've been to check my car. Been chucking it down all day. I have no water around that seal. The only water that was there was after I lifted the boot up and watched it run down to it. Seems that the seal around the boot is doing its job. Had a look from the underside and along the wiring harness and no water. I'll remove the trim at the weekend if the weathers alright but looks like at the moment but it's definitely one to watch.

Just out of curiosity, do you have a warranty at all?

That's the thing it is a single not double seal that's only wet once you open the boot lid. So not mega serious probably but still a single seal is not good where a flood of water can run by it when opening the boot.

I don't believe the OP has a warranty having sourced his own pump.

[Jasey]

Definitely one to keep an eye - Cheers all for the heads up