Big Red Cat said:
I had some work done on the Zed at Redish Motorsport, Bristol on Saturday. While the car was up on the lift I got James to check the roof drains. Mine were fine but he said they had a Zed in recently where the owner could hear water sloshing about in the door area. They tracked it down to a blocked roof drain, the water had backed up so much that it had gone down into the sill under the door.
Thanks for the info FW, hope all has been well with the 3.4S steering rack since the work on Saturday?
I can confirm, we've had multiple Z4's in with water ingress issues. All of them bar one have been down to blocked roof drains.
I don't mean the bottom exit of the drain (underneath the car) but the entrance to the drain which is down in the lower deck of the roof compartment (beneath the hinges of the roof).
Very hard to see even with a torch and knowing where to look.
Years worth of water will wash dirt, grime, tree deposits etc off the roof and into the roof compartment and then into the drains.
It then builds up and creates a film/layer of dirt and silt which restricts water flow INTO the drain, and in extreme cases can block it altogether.
In heavily rain that water will sit on top the silt and rise due to a total block or a restriction.
As the water rises (takes some time) it eventually spills over the top of a plastic 'bed' at the bottom of the roof compartment (under the roof hinges).
It spills forward into the bodyshell and ends up traveling through the corner of the rear bulkhead cavity and enters the B-pillar where it travels to the sill.
Once in the sill, it can't escape and collects until you hear that sloshing sound.
If it's in there for some time, or builds up to a good volume of water it WILL enter into the cabin of the car and start to saturate the carpet(s) as it spreads around the floor pan of the bodyshell.
It's all perfectly fixable and normally just requires the roof drain(s) cleaning out.
You will also need to lever out one or more of the plastic jacking supports to allow the water to escape.
Drive backwards and forwards with the jacking supports out for 1 day to make sure almost all water is out.
If the water has entered the cabin and got the carpets wet, you will want to remove the seat(s), rear bulkhead trims, rear carpet section, and possible front carpet section to dry it out.
We had a Z4 in recently which was so wet inside it killed the NS Airbag B-pillar Satellite ECU which then had to be replaced and coded.
Cleaning the roof drains is possible on the OS (right side) as its just about visible with a torch (roof down) through the roof mechanism hinges.
We use stiff (but flexible) wire to push and break up debris, and then a compressed air line and tubing to enter the tube and blow it out.
You can't get to the NS drain (left side) as the motor sits directly above it. The only way to clear the entrance to the drain is by removing the roof motor.
You could try to blow up the tube in reverse but that's not as effective as blowing downwards and clearing the entrance.
You can normally locate your problem by listening to what side the water slosh is on.
If it's the right side its straight forward, if it's the left side it's tricky work as the motor is in the way of the drain.
Hope this info helps.
I have got lots of pictures of the subject, and even a borescope video showing how we enter a drain, go all the way through it and come out underneath the car and prove it's totally clear. They're on an old hard drive at the moment but hopefully I'll put them on our YouTube channel or Facebook page one day.
If you have any questions of would like to book in for any water leak or water ingress issues please call me in the workshop - 01179 781889
Best regards,
James
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