Roof hydraulic test for top not moving

Jade · Post by **Jade** » Wed Dec 27, 2017 2:27 am

Hi, new Z4 owner, and mechanic by trade, and I just now purchased a Z4 with a top that doesn’t work.

I have the top out and have tried bench test it. You could always hear the motor work, and upon inspection there is very little corrosion on anything except a bit on the banjo fittings, doesn’t seem to be any leaks or anything.

I took off the motor and hydraulic lines and tested the motor, fluid will come out one side quite vigorously, but when motor polarity is reversed, very little (maybe 4-5cc’s of fluid per 30 seconds) comes out.

Is that reason enough to think the hydraulic part of the unit doesn’t work? Should there be equal flow of fluid in both ports? Can just that unit be purchased without the expensive motor?

The roof does absolutely nothing, not even try to go up or down with the motor running.

I’m hoping this will help some others, as I do hear a bit on this forum “I can hear the motor running but it doesn’t do anything” and then they go and buy the hydraulics and the motor, hope to save them a few dollars by having a proper diagnosis and test.
Thanks

firebobby · Post by **firebobby** » Wed Dec 27, 2017 10:32 am

Welcome to the forum.
If you have been a lurker for a while, you will be aware that there a members who do roof motor refurbs and moves. I'm sure these members will be along soon and your problem will be resolved.
A bit more info of your Zed and some photos would help too.

Post by **srhutch** » Wed Dec 27, 2017 11:33 am

Could be as simple as the emergency red handle in the wrong position in the boot.

What lights come on by the button and does the roof unlatch at the front?

Number5 · Post by **Number5** » Wed Dec 27, 2017 1:22 pm

Is the Hydraulic Bypass valve stuck in ?
Very often when you pull the red handle it will push in the valve to allow manual operation ( letting the fluid bypass the valve) and then it stay's in even though the red loop has been released.
Remove the cable assembly off the pump/motor and get some WD40 in and around the 'ball-valve' and press it in/out until it moves freely.

Ducklakeview · Post by **Ducklakeview** » Wed Dec 27, 2017 2:49 pm

Number5 wrote: ↑Wed Dec 27, 2017 1:22 pm Is the Hydraulic Bypass valve stuck in ?
Very often when you pull the red handle it will push in the valve to allow manual operation ( letting the fluid bypass the valve) and then it stay's in even though the red loop has been released.
Remove the cable assembly off the pump/motor and get some WD40 in and around the 'ball-valve' and press it in/out until it moves freely.

+1 although if it's well and truly seized, remove the blanking plug on the opposite side and give it a tap from behind.

Mike

Jade · Post by **Jade** » Thu Dec 28, 2017 1:56 am

Yeah have tried all those, opened up the blanking plug opposite and spray stuff down there, but haven’t tried remove any of the brass fittings deep inside there (as yes, I have disconnected and tried the bypass valve, doesn’t seem to be much difference in how it acts)

Number5 · Post by **Number5** » Thu Dec 28, 2017 10:28 am

Hi Jade,
It sounds like you've done all of the logical tests. If its pumping on one side of the pump I would expect you to get roof movement in one direction and then by flipping the lines over, restore movement in the opposite direction, which would indicate a weak side on the pump.

I think its time to get hold of another motor pump and try it, even if you can just borrow one ?

One last thought... are you sure the motor is turning the pump and that you've got the tiny steel insert fitted in the centre hole of the plastic disc that sits between the motor and the pump and that the connecting pin and spring are engaged. It just sounds like the motor (even though spinning) possibly isn't turning the pump ?

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