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Discussion Starter #1 (Edited)
I posted this in another thread here about my soft top, but thought I'd post it as a separate thread hopefully to get more eyes (and ears) on the topic.
Having just replaced the soft top motor and reassembled everything the top does open and close okay, but when closing, just before the locks engage the top of the windscreen (apologies if the terminology is not quite right) there is a loud buzzing or vibrating type noise. It sounds like it's coming from the soft top motor area but I'm not sure what it is.
Here's the link to a video with the noise I recorded.



Anyone know what might be causing this? Sound insulation housing vibrating against body of car? Motor itself?

Thanks
 

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That's the pump motor taking up the load of pressing the top against the windshield. Mine does the same thing.
 

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Discussion Starter #3
Strange it never did that before. It's quite loud. I guess I'd need to hear some other tops to compare it with. If I was buying this car new and I heard that noise I'd be having some doubts about it...
Thanks for the reply
 

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Mine sounds basically similar but with much less of that last couple of second of buzzing. Do you actually feel the top vibrate during the buzzing or it's just noise?
 

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On mine it's just noise. I've been researching to see if there's a programmed setting somewhere to adjust the pump cutoff, but I haven't found anything to date. I don't have INPA yet so I haven't had a chance to peruse through to see if there's anything there...
 

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Sounds normal to me - mine has always changed pitch like that once the roof presses up against the windshield header. It sounds like a typical hydraulic system bypassing when it reaches a stop - doesn't hurt anything, and keeps up the clamping pressure while the latches engage. I doubt there are any settings, but if there were I don't think you'd want to change them.
 

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Mine did it before the motor died, but the volume level is much greater now than it was before. I'm thinking maybe sopping wet foam in the motor housing was a better sound damper than the dry foam in the new housing......:)
 

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Discussion Starter #10
Thanks for the comments everyone. There doesn't seem to be any vibration of the top, and it does it when the roof presses against the top header (windshield). I would have thought the previous motor full of water and rust would have been worse for noises like that.
It just seems like it's overextending itself, or spinning on as the top locks engage. I got someone to close the roof while I had a look through the back window and the motor housing (sound insulation) did not seem to move or vibrate at that 'noisy' part of the operation. It's got me beat (for now) but at least I have a working roof back again.
 

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Thanks for the comments everyone. There doesn't seem to be any vibration of the top, and it does it when the roof presses against the top header (windshield). I would have thought the previous motor full of water and rust would have been worse for noises like that.
It just seems like it's overextending itself, or spinning on as the top locks engage. I got someone to close the roof while I had a look through the back window and the motor housing (sound insulation) did not seem to move or vibrate at that 'noisy' part of the operation. It's got me beat (for now) but at least I have a working roof back again.
Read up on how a hydraulic circuit works. When the top reaches the windshield top rail, the pump continues to run to maintain pressure so the electric latches can secure it - but the rams cannot push the top any further. The pump continues to run at a fixed speed - the hydraulic pressure above a preset limit is returned through a relief valve. The strong audible noise in that end phase of the top cycle is indicative of a good motor, not a bad one. You should start worrying when then sound gets weaker.
 

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Read up on how a hydraulic circuit works. When the top reaches the windshield top rail, the pump continues to run to maintain pressure so the electric latches can secure it - but the rams cannot push the top any further. The pump continues to run at a fixed speed - the hydraulic pressure above a preset limit is returned through a relief valve. The strong audible noise in that end phase of the top cycle is indicative of a good motor, not a bad one. You should start worrying when then sound gets weaker.
Except I don't believe the Z4 pump has a relief valve so the motor is just running at higher pressures until the front latches close to complete the closing cycle and turn the motors off. It doesn't hurt anything to run in that mode for a couple seconds and the motor isn't stalling so no risk there. It's entirely possible that not having this noise is a sign of impending failure due to motor corrosion and the motor may actually be stalling, thus the cessation of noise as soon as the front bow makes contact with the window frame.
I also personally think that the water soaked foam in the motor housing provides better sound attenuation too so if your motor was making this noise and then it gets softer or goes away that may not be a good thing! :yikes:
All just speculation and I have absolutely no intention of testing this theory on purpose.... :)
 

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I've never had one apart, but I'd be very surprised if that pump did not have an integral relief valve - pretty well all hydraulic circuits do. When the pump is turning, it needs to move fluid - and when the top has bottomed on the windshield header the rams are stopped and holding the roof tightly down. The relief valve simply allows the excess fluid pressure to circulate back through the reservoir, by opening once a pressure limit is reached.

It's much like the power steering on a car (those that use a constant flow hydraulic pump). When you turn the wheels all the way to one side, the steering hits the limit stops and the power assist has nothing it can push any further. That's when the pressure peaks, the relief valve opens. and you can hear an audible buzz/moan from the engine compartment as long as you continue to hold turning pressure on the steering wheel. Note it will still keep the wheels turned at their limit while doing so - it's just relieving the excess pressure from the pump.
 

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Discussion Starter #14 (Edited)
I've never had one apart, but I'd be very surprised if that pump did not have an integral relief valve - pretty well all hydraulic circuits do. When the pump is turning, it needs to move fluid - and when the top has bottomed on the windshield header the rams are stopped and holding the roof tightly down. The relief valve simply allows the excess fluid pressure to circulate back through the reservoir, by opening once a pressure limit is reached.

It's much like the power steering on a car (those that use a constant flow hydraulic pump). When you turn the wheels all the way to one side, the steering hits the limit stops and the power assist has nothing it can push any further. That's when the pressure peaks, the relief valve opens. and you can hear an audible buzz/moan from the engine compartment as long as you continue to hold turning pressure on the steering wheel. Note it will still keep the wheels turned at their limit while doing so - it's just relieving the excess pressure from the pump.
Thanks for the info on hydraulic operation (don't need to 'read up on hydraulics' now :))
The consensus seems to be that the noise is not a bad thing, the motor's working fine. But it's just a damn annoying noise. If I was buying this car new and it made that noise I would be having serious doubts. Fortunately I love the car with a working roof so will learn to live with the strange new sound.
Just out of curiosity, why doesn't it make this same noise at the other end of travel, when the roof is down and the hooks are locking it down? I would have thought it was the same process - ie, the motor runs on while the hooks are locking. But that part of the process is no different, noise wise, as when the old motor was in.
 

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My car makes very similar sounds when it reaches fully open or fully closed - does yours not change in pitch at all when the roof reaches the fully retracted position? If the noise is markedly different, perhaps there is some part interference, mounting issue, etc. that is causing a sympathetic vibration that amplifies/exacerbates the noise only when the roof is fully extended. It's very difficult to judge amplitude from a video clip - but the pitch, duration, etc. 'sounds' very similar to mine.

I've never at any point considered the sound the top makes to be obnoxiously loud or overbearing. As yours obviously concerns you, I'd suggest your best bet is to compare with another Z4, so you have a live basis for comparison. Good luck! :thumbup:
 

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Discussion Starter #16
My car makes very similar sounds when it reaches fully open or fully closed - does yours not change in pitch at all when the roof reaches the fully retracted position? If the noise is markedly different, perhaps there is some part interference, mounting issue, etc. that is causing a sympathetic vibration that amplifies/exacerbates the noise only when the roof is fully extended. It's very difficult to judge amplitude from a video clip - but the pitch, duration, etc. 'sounds' very similar to mine.

I've never at any point considered the sound the top makes to be obnoxiously loud or overbearing. As yours obviously concerns you, I'd suggest your best bet is to compare with another Z4, so you have a live basis for comparison. Good luck! :thumbup:
The motor does change pitch when locking in the 'down' position but not as loudly as when locking the roof in the 'up' position - that's what had me concerned as it used to be pretty much the same 'run on' noise from the motor in both directions locking.
Very good idea about comparing with another Z4 - there's one in the car yard not far from my work so I might pop in for a look...
As DC Wright jokingly suggested, maybe I need to pour a bucket of water back into the sound insulation to 'fix' it :yikes: :rofl:
 

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Mine makes the exact same noise when closing

Hi, I just came across this thread now.

My roof just starting exactly the same noise as yours (I checked your YouTube vid). Its noticeably louder for the last 2 seconds or so during closing.

I would really like to know if this ended up being a problem or not?
I just replaced the hydraulic pump in my car 3-4 months ago so will be really pissed if theres another issue.

Many thanks for your feedback.
 

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Discussion Starter #18
Hi, I just came across this thread now.

My roof just starting exactly the same noise as yours (I checked your YouTube vid). Its noticeably louder for the last 2 seconds or so during closing.

I would really like to know if this ended up being a problem or not?
I just replaced the hydraulic pump in my car 3-4 months ago so will be really pissed if theres another issue.

Many thanks for your feedback.
Hi,
I've replied on Youtube, but the consensus is that there's no fault, the noise is normal (just a bit annoying). I've learned to live with it and it doesn't bother me too much any more.
Just got the dreaded DSC/DTC/Brake warning lights on the dash so much worse things to worry about now :cry:
 
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