Z4 noise, crunching from center console

[Jstic]

Finally found the time to complete this repair. The initial gear position and diagrams are attached. The PDF file also gives the part numbers for anyone who needs to buy the new gears. Cost is less than $30 for the plastic parts.

I think I have also discovered what caused this problem. When I pulled out the cabin air filter, a bunch of leaves, small twigs and other debris was clogging the fresh air flap opening, which did not allow the gear and actuator to close it properly. This is probably what caused the actuator to skip gear teeth as the white gear was trying to turn the black gear(see previous posts for photos) but the black gear which controls the flap, had no where to go.

[ANUSTART]

Excellent! Thanks for posting this. I'm going to dig into it this Spring.

[Jstic]

Here is a picture of the two gears I replaced, damage and missing teeth circled.
At first look, I did not see this, once I took them out the damage was far greater than I first thought.

[gas-can]

Hi Jstic,

Thanks for posting that alldata sheet up and for the pics. I noticed the same thing in the new z4 I got, so this seems to be a common issue...

I'm going to do a full service to the car either this weekend or next, and this is on the itineary. Do I have to just pull the panel underneath the glovebox and the glovebox? Or do I have to pull apart the entire dash? IIRC, that panel is held in by just a couple of screws, right?

Thanks for sharing this info with us!

gas-can

[Jstic]

Yup, 2 screws. That is all I pulled. The General Module for body electronics is attached to the backside of the panel, so don't just yank the panel out. Lower it a bit after removing screws and you will see the module. It is held in place by two 8mm bolts that lag into the plastic panel. I also removed the passenger seat so I could stretch out a bit and work comofortably on my back. Be very patient, this job took me all of 8 hours total.

The TIS says to remove the glove box. I did that initially and also removed the passenger side knee airbag. It really did not give me any better access, I would have had to take out the fuse panel to be able to gain access to the actuator and gears. I found that I could do everything I needed to do by working on my back rather than taking the dash apart. Others may find it easier to follow the TIS and remove the glove box and air bag unit. If you are big,(I am 5'11" and 190 lbs.), you may not be able to do it the way I did.

[SD Z4MR]

Originally Posted by Jstic

Finally found the time to complete this repair. The initial gear position and diagrams are attached. The PDF file also gives the part numbers for anyone who needs to buy the new gears. Cost is less than $30 for the plastic parts.

I think I have also discovered what caused this problem. When I pulled out the cabin air filter, a bunch of leaves, small twigs and other debris was clogging the fresh air flap opening, which did not allow the gear and actuator to close it properly. This is probably what caused the actuator to skip gear teeth as the white gear was trying to turn the black gear(see previous posts for photos) but the black gear which controls the flap, had no where to go.

So how did this stuff get past the cabin air filter? Was it not installed or not installed correctly? When I replaced mine there were a few leaves on the inlet side, but the outlet side was clean. That cabin air filter is a PITA, it's much easier to replace on my wife's 335is Coupe.

[Rick F.]

Originally Posted by Jstic

Finally found the time to complete this repair. The initial gear position and diagrams are attached. The PDF file also gives the part numbers for anyone who needs to buy the new gears. Cost is less than $30 for the plastic parts.

I think I have also discovered what caused this problem. When I pulled out the cabin air filter, a bunch of leaves, small twigs and other debris was clogging the fresh air flap opening, which did not allow the gear and actuator to close it properly. This is probably what caused the actuator to skip gear teeth as the white gear was trying to turn the black gear(see previous posts for photos) but the black gear which controls the flap, had no where to go.

Jstic,

Excellent, really excellent. Thanks for your diligence in tracking down this information and sharing it with us!

Rick F.

[Jstic]

Originally Posted by SD Z4MR

So how did this stuff get past the cabin air filter? Was it not installed or not installed correctly? When I replaced mine there were a few leaves on the inlet side, but the outlet side was clean. That cabin air filter is a PITA, it's much easier to replace on my wife's 335is Coupe.

The cabin air filter is after the outlet flap in the air flow cycle. The filter is actually part of the problem as it is within 2mm of the open flap and the leaves rest up against the filter and accumulate. If fresh air flap is left open for a long period of time, leaves and debris accumulate and once they hit the filter, they have no where to go. On my car the leaves had accumulated about halfway between the cabin filter and the inlet under the hood. Bottom line, check or change air filter regularly.

[SD Z4MR]

Originally Posted by Jstic

The cabin air filter is after the outlet flap in the air flow cycle. The filter is actually part of the problem as it is within 2mm of the open flap and the leaves rest up against the filter and accumulate. If fresh air flap is left open for a long period of time, leaves and debris accumulate and once they hit the filter, they have no where to go. On my car the leaves had accumulated about halfway between the cabin filter and the inlet under the hood. Bottom line, check or change air filter regularly.

Thanks, good to know. It was such a PITA to change I tried spending as little time as possible wedged in under the glove box!