Roof motor working(?) but roof ain't moving...

[FelixTheCat]

Hi,
I went to lower my roof and after holding down the button the roof automatically unhitched from the top of the windscreen as usual, but didn't peel back like it should.

I could hear the motor whirring round on the left side. Exact same noise as it usually makes, but the roof didn't move.

I hadn't lowered the roof for a couple of months. Could there be a problem with the hydraulics? I could move the roof back manually, but nervous that this would add to the problem if part of the mech is damaged, so I won't do it again.

It was at the dealer for a couple weeks at the end of last year, which included them lots of faffing around with the wiring in the boot. Not sure if this has cocked anything up.

I had a look through old posts to try and find something on this but couldn't find the exact same problem, so any new advice (or links to old) would be much appreciated.

Thanks

[AndyS]

Not sure if this applies or not but page 20 of the manual mentions assisting the power operating mechanism by hand the first time it's closed if the soft top has been stored down for a lengthy period, e.g. the winter months when the hard top was in use.
I'm guessing it could be a possibilty the same thing applies in reverse.
Don't quote me on this though as I have no experience of this personally.

[Tommo]

This sounds exactly like how my roof went when it finally died from water corrosion. The latches would work perfectly but the roof wouldn't peel back. Then a few tries later it would work perfectly. Around 1-2 months later it finally died and the motor had to come out. (Big job!)

[Z4play]

Is the part in the boot that raises and lowers, on the low setting.
Its for adding extra space in the boot.
Not sure what it's called. You need to turn the two knobs.

[Shipkiller]

Is the part in the boot that raises and lowers, on the low setting.
Its for adding extra space in the boot.
Not sure what it's called. You need to turn the two knobs.

It's called the 'compartment floor' and if it was UP, then the locks would not unlock.



Back on topic, Felix, you said that the motor makes its noise but there is no movement?

If the bypass in the boot has been pulled and set, then the motor would run but there would be no pressure to move the top. Check that out first.
If the bypass is ok, then you have other issues. See below. Also, there is no wiring for the softtop in the boot.

Just to be clear, hydraulics are a sealed system. If you have a hydraulic problem, then two things:
1. A leak. Chances are less than 5% for that. If you had a leak, you would know. NEVER heard of a BMW Z4 with a hydraulic leak. There is less than a pint of hydraulic fluid in the entire system.
2. Motor is bad. The motor drives the hydraulic pump. If the pump does not produce pressure, no movement to the top.

[FelixTheCat]

Thanks for the replies guys.

Yep, I checked the compartment floor thing on the day, it was already in the lower position.

What is the 'bypass' in the trunk please Shipkiller? Is that something different? Only other thing I know in there is the pull chord to release the roof from the down position (IIRC).

I'll be able to do more investigation, motor etc. when I get a dry day. Without any workshop space right now, it's difficult to do the job to access the motor, unless it's going to stay dry for a bit. That and I need the car daily - Ah, the British weather!

P

[un1eash]

The red pull cord releases the roof from the motor to allow manual operation.

[Andy]

Yep.. Mr Shipkiller is usually right, but that was my thought too, check the Red pull chord is angled correctly, as it basically acts as a bypass valve for the fluid, allowing you to move it manually

Rotate it, you should feel it lock, try again.

[Shipkiller]

The Bypass (Red Handle) is a bowden cable that is attached to the hydraulic motor which activates the hydraulic bypass valve which allows the oil to flow freely, without the pump to push it.

To set it, you PULL the handle and then move the cable laterally into the slot on the tube. This keeps the cable taught, keeping the plunger on the pump depressed, and allow you to move the top by hand.
To unset, you PULL the handle and move the cable OUT of the slot allowing the handle/cable to move back into the tube housing.

Topics to look for using the search feature of the board:

http://www.z4-forum.com/forum/viewtopic ... 32&t=11274
http://www.z4-forum.com/forum/viewtopic ... 32&t=10189
http://www.z4-forum.com/forum/viewtopic ... 32&t=10190
http://www.z4-forum.com/forum/viewtopic ... 32&t=11615

[FelixTheCat]

thanks for the prompt and thorough replies again.

Yeah, the red pull was in the right place, but I've since pulled it out, turned, and let it go in again. Did this a few times and at first it was sticking and there seemed to be some slack in there but then it all freed up and the roof is working fine again now, so I assume there was something sticking in the bypass/valve/plunger somewhere. Just pleased it isn't going to cost me anything this time.

[no fit state]

thanks for the prompt and thorough replies again.

Yeah, the red pull was in the right place, but I've since pulled it out, turned, and let it go in again. Did this a few times and at first it was sticking and there seemed to be some slack in there but then it all freed up and the roof is working fine again now, so I assume there was something sticking in the bypass/valve/plunger somewhere. Just pleased it isn't going to cost me anything this time.

This is well worth knowing about. Can you imagine replacing the motor when all you really needed to do was this?

[The_Real_BruceWayne]

In fact, I'm going to try this tomorrow.. before doing an open heart surgery on my Z4.