View Full Version : DIY: Z4 Convertable top drain claening

10-27-2007, 10:52 AM
A long, long time ago in another forum called Z4um.com (long gone) there was this post. It recently resurfaced on another site, and is great preventative maintenance for the Z4.

So here you go fellow Z4 drivers:

Just trying to save cached How-To's from Z4um.. this originally posted by "GV from Belgium"...

There are quite a few zzzz with a faulty soft top hydraulic system out there. The reason for the problem: water!
The soft top motor is rapped in an insulating foam and is located in the area where the soft top folds down.
There is a water drain on each side. The drain on the right side (side of the fuel filler cap) is only visible if you watch closely between the soft top mechanism (top down) with a flashlight.

The drain on the left side is not visible because the soft top motor blocks the view.
Now what happens: these drains get clogged, water can't get away and gets absorbed by the insulating foam. Result: soft top motor fails. (pic courtesy of www.zroadster.com (http://www.zroadster.com) !!!)

The repair is pretty difficult as the complete top needs to be removed to access the soft top motor (and we all know what can happen when your skilled dealer needs to do that kind of repair).
When I'm writing this DIY, there are at least 20 zzzz I came across that had this problem.
So, lets get to work!! The goal is to unclog the drains so the water can run away freely.
You need:
1 flat screwdriver
1 8mm spanner
1 10mm spanner
1 vacuumcleaner
1 tube inner diameter 6mm or 4mm
1 or more jackstand(s)
1 jack
Lets start at the RIGHT side. You can see the inlet of the drain if you peek with your flashlight in the space where my finger is:
Jack up the car and secure the jackstand!! (very important!!)
You could remove the wheel, but that is not necessary
Remove the wheel arch cover by removing the 2 8mm bolts (part 51718204807) and the 1 plastic 10mm nut (part 51711958025) together with the splash thingy by removing 2 expanding rivets (part 51118174185), 1 8mm bolt and 1 plastic 10mm nut.
The rivets are a pain in the a$$.... I broke them so I replaced them with new ones.
The splash thingy and the wheel arch cover come off as one piece:
Make sure to unclip the ABS/DSC sensor that is clipped onto the splash thingy:
Cover and splash thingy removed:
Now, get UNDER your car and you will see the drain!!
Pull out the drain!
Drain removed from the car:
Whoever designed this should be shot or at least fired! The drain hole is about 8 mm in diamter, but the internal tubing of the drain is only 5mm in diameter. Must get clogged eventually!!
I used compressed air from THE TOP and flushed to system with some Evian mineral water:
Here is a small example of the crap that came out (a lot more was flushed out with the compressed air):
Put everything back and get to work on the other, more important side (because the soft top motor is located on that side).
Same as on the right side, only here I didn't use compressed air, as the system is only accessible from the bottom. Instead, I modded my vacuumcleaner somewhat Smile
6mm tube goes into 4mm tube... and that tube goes into the bottom of the drain:
The "problem" is that you can't be 100% sure the left drain isn't clogged anymore because you can't verify it by flushing the system. But, judging by the amount of crap that came out of the drains it looks like this will be a recurring DIY Smile
Don't forget to put everything back and... DONE