Roof issue - not motor

[AMM]

Hi. I'm looking for some advice regarding a potential roof issue on a car I'm going to look at (hoping to become a Z4 owner).

The current owner has advised that the roof was working well until a couple of weeks ago when there was a sound like a snapping cable. Now it seems that the motor still works but the roof won't go up and down.

Before progressing with this any further, I'm keen to understand potential causes of this issue and how expensive it could be to resolve. Can any more knowledgeable forum members make any suggestions along with a worst case cost for correcting the issue please?

Thanks

 

[enuff_zed]

Good evening.
To start with, the operating mechanism is purely hydraulic. The motor is linked to the pump with a brass pin. Very unlikely that will snap.
If the motor is still running then logically it is a failing in the hydraulic circuit.
1. Bypass valve operated. But this is sprung loaded out and would need the red ring pulled to operate it.
2. Loss of connection between the motor and the pump. Need to get it into the boot and separate the halves to see if anything is broken.
3. Hydraulic leak. Need to get it into the boot and check the reservoir.
4. If the fluid has gone, then where? Probably one of the connections at the rams. That needs the roof lifted to investigate and replace the pipe.
I would see this as worst case. £180 for a set of four replacement pipes. (Why would you only replace one after all that effort). A days work to remove the roof, replace the pipe and rebuild.
I'm about to undertake exactly this with a fellow member, having never done it before. My time is not costed but I reckon you'd be well up to $5-600 at a garage.
For starters, until the motor is relocated to the boot you are grabbing at straws tbh.

thinking about it, you'd also need to ascertain whether the roof is unlocking from the front. Though I think I'm right in saying that if it didn't then the rear motor would not be triggered to run.

Assuming you won't be able to relocate the roof motor during an initial viewing then the best you can really do is pull the red ring in the boot, operate the switch to unlock the front, then manually pull the roof back.
then get a strong torch and look down beside the rams at the front of the roof each side.
If you can see any fluid in there (about 6 inches down) stick something in to sample it. If it's oil then either walk away or knock a minimum of £500 off the price to fix it.

 

[AMM]

Thank you, that's very helpful.

The current owner has said that the roof is working manually so presumably the bypass has been operated. Apologies for my ignorance, but to look at the rams at the front of the roof each side, do you mean to look down at them once the roof as been folded down? Thanks.

 

[enuff_zed]

Thank you, that's very helpful.

The current owner has said that the roof is working manually so presumably the bypass has been operated. Apologies for my ignorance, but to look at the rams at the front of the roof each side, do you mean to look down at them once the roof as been folded down? Thanks.

Yes, you need the roof folded down, then shine a torch down beside the ram and look for any signs of fluid. Dip it with something to see if it's oil or water.
Whereabouts are you?
Maybe someone close enough to come with you and offer a little advice?