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Thread: Z4 Top opening slowly, stops part way

  1. #1
    Join Date
    Aug 2022
    Location
    NY
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    My Cars
    2005 Z4 3.0i

    Z4 Top opening slowly, stops part way

    2005 Z4 3.0i
    Top begins to open… moves very slowly and stops about 1/3 way. At that point I attempted to close - I can hear the motor whine but no top movement. I grabbed it with my hand to assist it and it closed and latched easily.

    It’s as if it’s very low on fluid.

    Appreciate advice on potential causes. Seal failure? I see no signs of fluid leakage. I’m assuming the top will have to come out. I’ve see. Posts where top motor is pulled out through the trunk - is this a viable option? Also - I do not see the infamous red pull ring. I’ve adjusted the tray up and down by moving the know on the left hand side.

    Comments welcome.

  2. #2
    Join Date
    May 2017
    Location
    Georgia
    Posts
    165
    My Cars
    2003 Z4 2.5
    I forced my top down to move the motor which was sitting in water. I got the motor moved and refilled it and motor came to life. Top went up and down , but ,when forcing it down, I blew out the hydraulic seals in the hinges. I had oil on the concrete in front of the rear tires. My red valve was frozen in place.

  3. #3
    Join Date
    Aug 2022
    Location
    NY
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    4
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    2005 Z4 3.0i
    Considering it’s a closed system, it shouldn’t be low on fluid unless there is a leak somewhere. If I can access the motor and refill it that may help temporarily, but it will likely fail again if it’s losing fluid - no?

  4. #4
    Join Date
    Sep 2018
    Location
    Mechanicsburg, PA USA
    Posts
    123
    My Cars
    2003 2.5 BMW Z4
    Hey

    From your posting your motor is running but the top is not moving, correct? If so, then it's hydraulic. Your correct, it's a closed system.

    Ok, let's try a pressure check. Start the car, then push top down and when the top releases from the windshield turn the car off. Now manually attempt to move the top down/up. Does it move freely. It should be as hard as a brick. Generally, if you can move the top freely without engaging the emergency release there's a hydraulic problem.

    Ok, go on youtube and search under e85 z4 convertible top and find where the red emergency roof release is and how to use it. Is it engaged? or when you found it, was it in it's normal position?

    However, you should be aware that the emergency release might be jammed at the pump. You should also be aware that if your system is fully pressurized (top hard to manually move) then this issue might be the pump which is joined to the electric motor.

    are you sure that the drains on both sides (driver/passenger) are open? If either is blocked your fluid may be in the blocked drain and you would never see the leaking fluid.

    The hinge lifters have seals where the metal nipples of the hydraulic lines plug into it (one on top, the other on the bottom). The bottom seal is the one that almost always fails and leaks fluid out since it is the line that lifts the weight of the top. However, there is another way a hinge lifter can fail without it causing any fluid leak. Inside of the lifter is a piston with a rubber ring around it. This piston is pushed up/down by the fluid. If over time the rubber ring around the piston should fail then instead of pushing the piston, the hydraulic fluid simple passes thru the broken rubber ring.

    This issue might also be a broken/rusted hydraulic line (with a blocked drain).

    Your best bet is to pull the top and run it off the car. You can check the fluid level in the motor and at the same time make sure the emergency release at the pump isn't jammed open. If the fluid level is low you can top it off and run it off the car to determine the location of the leak. Honestly, an off the car inspection will give you the best results.

  5. #5
    Join Date
    Aug 2022
    Location
    NY
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    My Cars
    2005 Z4 3.0i
    JAS1169 - thank you so much for your detailed response. A few additional points:
    - when the top first failed (open) I could not pull it close. I was able to pull it up 12-18”, but at that point I was clearly pulling against the hydraulics and it wouldn’t move.
    - I popped the trunk looking for the “release”. I didn’t see the red ring I was looking for (?). I’ve really looked. Could it be wedged somewhere out of position? In any event, I turned the black knobs that change the shelf height and I could then easily pull the top up.
    - I then tried to lower it automatically. It unlatched and moved back very slowly then stopped about 1/3 of the way. The motor continued to run but no movement.
    - I then pressed the close button. No movement. Grabbed it with my hand and easily pulled it closed.

    I thought there was a way to snake your hand down into the driver side quarter panel to check for water. I can’t seem to get my hand in there. Tried to take a photo and I don’t see much (top of the motor cover?). I can’t tell if there’s water there. Not exactly sure where the drain is under the quarter panel (I looked yesterday and it wasn’t obvious).

    Does it make sense that there’s no red ring? Could that have been replaced by the black knobs I’m tuning to adjust the shelf height?

    Not sure I’m up for removing the top. I already have two ongoing projects (apartment renovation for my daughter and I’m hanging gutters on the garage). Plus I’d have to work in the driveway (the garage has my other cars and they are not allowed to sleep outside!). I’ll watch a couple of videos - but if I do tackle it - what’s the level of difficulty and time required? Could I get it off and back on in an afternoon (assuming average backyard mechanic skills)?

    Is there anything else I can check without pulling the top?

    Thanks again -
    Bill

  6. #6
    Join Date
    Sep 2018
    Location
    Mechanicsburg, PA USA
    Posts
    123
    My Cars
    2003 2.5 BMW Z4
    Hey Bill

    No, the black knob has nothing to do with the hydraulic system. While you were fooling with the black knobs, gravity drained the fluid in the hydraulic line allowing you to close the top without effort. You can reach the motor case from the drivers side quarter panel. However, the drain area which floods is below, and access is blocked by the motor housing.

    Based on your posting I have a feeling that a prior owner of your car did a motor change and the emergency hydraulic release handle (red) was somehow misplaced/lost.

    I'm going to alter my recommendation, based on your ongoing other projects, as well as the fact that I believe your the kind of person who can live with a top that you lower and rase manually. Basically, you just want to enjoy the car.

    I'm recommending that you use the thru the trunk method and pull the motor/pump into the trunk. Once you have the motor/pump in the trunk you can put a old coffee can under it and loosen the 10mm bolts banjo bolts (no need to take them off) & drain the remaining fluid. Having access to the motor in the trunk should remove a lot of possible problems. Afterwards, you'll be able to release the top from the windshield with the down button and then manually bring the top down. You'll close the top by bring it up manually to the windshield frame and then push the top up button to lock it in place.

    This will allow you to use and enjoy the car until your ready to pull the top.

    There are a few youtube video's on doing this thru the trunk method.


    After viewing the youtube video's read this posting which is basically a step by step instructions (with pic's) of how to do the thru thr trunk method. I believe this is one of the best posting on how to do this.

    https://zroadster.org/threads/z4-roo...to-boot.19256/

    No, I didn't write this, I found it on a Z4 forum from the UK
    Last edited by JAS1169; 08-15-2022 at 03:48 PM.

  7. #7
    Join Date
    Aug 2022
    Location
    NY
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    My Cars
    2005 Z4 3.0i
    JAS1169 - you’re right about a couple of things. The motor was replaced several years ago by my European car mechanic, which might explain the missing red ring. You’re also correct that I’d gladly operate the top manually (same as my ‘65 vette), but the Z4 is my wife’s car. She has a high expectation that things work as they should.

    I may attempt to pull the motor into the trunk to see if there’s anything obvious I can address. Otherwise, the car will likely go to the mechanic. Thanks for the suggestions/support. If I get into it and find something interesting (or more likely, get into trouble) I’ll update this post.

    Thanks again,
    Bill

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