Z4 roof not moving, but everything seems fine.

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davidcharlescopp

Member
Hi all, I know this has been posted a lot and I've had a really good read of a lof of other threads. I'm now at the point of needing a little inspiriation. So my car is a Z4 2003 2.5. The roof packed up about 12 months ago due to water damage. I've replaced the motor and relocated it to the boot.

At first it worked brilliantly and since then slowed down and now doesn't move. The roof releases, the main motor turns, but there isn't enough power to move the roof down or up. If you give it a push with your hand it will move, but slowly.

If the emergency release is pulled the roof moves freely and the reservoir is filled to the appropriate level on the top of the motor.

The motor seems to spin quickly enough under load and with the emergency tab pulled it runs super fast.

The most likely scenario seems to be either air in the system or possibly a pinched line (I doubt the last one), but I've tried the suggestion of running the motor up and down to self-bleed and also run the motor back and forth with the tab pulled - no help.

Before I go and take the roof of again. Does anyone have any suggestions on things I might try?
 
The hydraulic pump could be worn out or the manual release valve may not be seated all the way and it is allowing the fluid to bypass.
 
Seal has probably gone inside the hydraulic ram (the black piston looking things) responsible for the roof open and close operation.

Not many people have done them on here, think there was a post from a guy in the states who did. Best thing to do is take it apart and have a look. You can buy seals online in a myriad of sizes. Alternatively try quarry motors breakers for a replacement ram.
 
Forgive the ignorance but are we talking about the unit that sits on top of the actual electric motor? When I replaced the seized motor I reused that part, so I guess it could be faulty.

Bumpy - thanks. The manual release ball was all gunked up when I removed the roof before. I cleaned it all out it seems to be fine.
 
Thanks PH. Sounds like the roof is coming back off and I'll take a look at them. The system is not loosing fluid, so I assume the broken seals are just allowing the fluid to bypass the piston.
 
davidcharlescopp said:
Thanks PH. Sounds like the roof is coming back off and I'll take a look at them. The system is not loosing fluid, so I assume the broken seals are just allowing the fluid to bypass the piston.
Click to expand...

Yes, exactly right. It just moves fluid from one side of the chamber to the other so you don’t get external leakage as such, just poor ram strength as it can’t hold the hydraulic pressure.
 
Turned out it was a faulty pump - the one on top the actual electric motor. Roof is moving fine now :D I guess that's what you get when you replace half the damaged part!
 
Good that you sorted it. I must admit I assumed when you said you replaced the motor, it included the pump on top!
 
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