MadaboutKitcars

How To – Release a stuck BMW Z300S Bonnet

Symptoms
Normally I pulled the release lever in the cabin and then went around to the front of the car where there was a lever I pulled to release the catch. I actually connected a piece of wire to this lever which I could pull through the front grill which made life easier. When I pulled the interior release lever the bonnet didn’t pop open a little bit like it does on normal cars but this is probably because of the weight of the re-enforcement I added under the bonnet.

Thinking about it now, it seems strange that I could pull the lever inside the cabin and it would stay pulled long enough for me to go to the front of the car and release the other catch. Possibly sticky cables and release mechanism. If you get these symptoms I would suggest you check and replace as required. Hindsight is so much more accurate than foresight.

Now when I pull the lever in the cabin and walk around the front to pull the lever nothing happens. Looking underneath the car it appears that the lever I pull at the front of the car, pushes against another piece of metal which should release the catch. This other piece of metal appears to have bent so that it is not releasing the catch.

The YouTube clip below shows all the bits that move and do stuff but unfortunately for a standar4d 3 series so useful for reference but not exactly the right instructions for a Z300S.
https://www.youtube.com/watch?v=e_73XgTOYjY

Diagnosis
The lever that releases the catches has bent. This needs fixing/replacing.

The reason it bent is possibly because the catch mechanism is seized or very stiff. This needs fixing/replacing.

The cables operating the mechanisms may also be seized or very stiff. This needs fixing/replacing.

The interior release lever appears to work in as much as the cable moves but there is no obvious sign that anything has happened. Ideally the bonnet should lift a little. This needs fixing.

I don’t ever want to do this job again so I will try and work out a fall back solution for opening a jammed bonnet. This needs inventing.

Actions
These will be updated as I make them up...

Maybe if its released on a spring fit a stronger spring to lift the extra weight as mentioned if pops up. Or those hydraulic pistons that extend slowly possibly short ones that raise to allow you to get your fingers in

First you need to choose the rainiest day ever to try and start work
[img] https://lh5.googleusercontent.com/-BXX6AuyumD4/U2uAH29r1VI/AAAAAAAAJ0M/gYhB6msm6UQ/w731-h548-no/IMG_20140508_124525.jpg[/img]

Then find somewhere dry to work. Remember that you will be working under the car so you will want lots of light and the car raised up. As you can see, my ramps are designed to be driven onto forwards so the weight of the engine makes it easy to tilt then to level. Unfortunately this would have meant putting the car into the garage nose first and working in the dark.
[img] https://lh5.googleusercontent.com/-gdi--DHSEPE/U2uAH-NZoRI/AAAAAAAAJ0M/fPL4VkHTP40/w731-h548-no/IMG_20140508_124601.jpg[/img]


The judicial use of brick and axel stands gets one side up and near level. If you look under the car to the other side you can see how much the ramps bend with the car on the wrong way round.
[img] https://lh3.googleusercontent.com/-Ru8O7ucUP94/U2uAH1whx_I/AAAAAAAAJ0M/hQgA_RisuIo/w731-h548-no/IMG_20140508_131720.jpg[/img]


Both side up, chocked with bricks and an axel stand each side
[img] https://lh6.googleusercontent.com/-TlpKr48JoOE/U2uAH7EewlI/AAAAAAAAJ0M/GOsilFg0CtI/w731-h548-no/IMG_20140508_134555.jpg[/img]

A trolley jack and a couple of wheels will also help hopefully. Notice that I ran out ofbricks so the left side is a bit lower. Also (not shown) is the fact that as I raise the car it moves slightly backwards so now the rear number plate is hard against the work surface. Hopefully no damage is being done there.
[img] https://lh4.googleusercontent.com/-IC7krdtqRy8/U2uAHyjYLUI/AAAAAAAAJ0M/Zo5CC7qdA5M/w731-h548-no/IMG_20140508_134602.jpg[/img]

More to come...

Well that’s ½ an hour spent under the car looking around for things to attack. Whoever decided the Z3 bonnet and grill should be replaced by a one piece unit should be bloody well hung! Actually it was me who decided and I am bloody well hung so that is one tick in the box.
I started looking at the rod that pulled the catch lever and tried to work out what it moved. The pictures below show the rod in the closed and then the open positions
Closed


Open


I then tried to see what the bit of wire I attached did. Again, closed and then open
Closed
[img] https://lh4.googleusercontent.com/-fDR4xX3whNw/U2uOTo-5zyI/AAAAAAAAJ3Q/0jPFlcZtSGs/w731-h548-no/IMG_20140508_141510.jpg[/img]

Open


Not sure if this helped at all until I suddenly realised what else I could see.
[Img] https://lh6.googleusercontent.com/-uDSjBLBQVR4/U2uQzMpLJMI/AAAAAAAAJ38/J4jL3QXeG5g/w731-h548-no/bonnetcatch.jpg[/img]

A quick look on the other side and ta-dah!! A black cable leading to the other bonnet catch
[img] https://lh6.googleusercontent.com/-SDFpcZdD_IU/U2uOTpEcj4I/AAAAAAAAJ3Q/JIDXRaonpTg/w411-h548-no/IMG_20140508_144140.jpg[/img]

Overcome with excitement and the need for a pee I have come inside to consider my options.

More to come...

You can do it. Come on!

Got the bastatd

The bonnet pins have a slot in the end. A long flat blade screwdriver just reaches and using my special super hero 'strength of seven baboons' power I managed to unscrew the drivers side pin so one side of the bonnet was free.



The passengers side was more awkward and I only managed to loosen it about a turn and a half before I had lost all the skin off my knuckles.



I resorted to getting the site to gently bounce the bonnet while I pulled the lever in the cabin for all I was worth. Suddenly it released. I scrambled under the car to release the safety catch and propped the bonnet open.
It was all just sticky catches so I will update tomorrow with cleaning and testing the bonnet catches before refitting them. Now I am going for a bath and beer.

A good not of advice is not to use the same foam square to lie on a you used the previous weekend while fibre glassing. My back feels like it has been dragged across a thousand metres of loft insulation

More to come...

Scottie's comments on how to remove a BMW steering wheel might also apply for stuck bonnets?







Don't try this at home people!

Okay, bath bathed and beer drunk it is back to the task in hand. Let’s get the bonnet catches working. With the bonnet open it is clear that it is the sticky catches that are causing the problem but first lets remove the bonnet pins so the bonnet cannot close itself again.

So much easier with the bonnet open
[img] https://lh5.googleusercontent.com/-aIrJ5FTQHSo/U20G5yr_GAI/AAAAAAAAJ_Y/qJTspzf9big/w731-h548-no/IMG_20140509_125104.jpg[/img]


And look at the state of the catch
[imgt] https://lh5.googleusercontent.com/-aiVgBdQzqks/U20G5_0dmgI/AAAAAAAAJ_Y/z5PQItyWlqA/w731-h548-no/IMG_20140509_125112.jpg[/img]


The other side still has the pin stuck in the catch and you can see the thread where it was unbolted from the bonnet
[img] https://lh4.googleusercontent.com/-Wl1lxg2d2yE/U20G5zV6KuI/AAAAAAAAJ_Y/uHUlJmTT3ao/w731-h548-no/IMG_20140509_125117.jpg[/img]


Use a T30 torq spanner to undo the three bolts holding the latch mechanism in place. The bolts are self tappers fitted at the factory so bastard tight. I had a lovely imprint of my Ratchet Rocket wrench by the time I had done both sides. I found it best to start with the bolt sitting vertically as if you leave that until last it is really awkward as the latch moves around a lot.
[img] https://lh3.googleusercontent.com/-1dv3fAbCC5U/U20G5woF3iI/AAAAAAAAJ_Y/yz4dMRqa4v4/w731-h548-no/IMG_20140509_125838.jpg[/img]


Now it is loose you can do the other side. The driver’s side latch has a cable coming in from the left which goes to the cabin and a separate short cable going right which activates the passenger side latch.
[img] https://lh4.googleusercontent.com/-0uWqr5Ug_ZU/U20G52giqmI/AAAAAAAAJ_Y/FffkZviWjz0/w731-h548-no/IMG_20140509_130212.jpg[/img]


Once you have freed up the latches you can see how badly corroded they were. At this point I was thinking I would need to buy new ones.
[img] https://lh5.googleusercontent.com/-Jub0Z2fh-Hs/U20G5ygHvxI/AAAAAAAAJ_Y/ba1ZsRnj1e8/w731-h548-no/IMG_20140509_160403.jpg[/img]


The latches are now stuck in the car with the cables from the cabin and between the two preventing you removing then. First remove the short connecting cable from the driver’s side latch. This is just a case of poking it about with a screwdriver until it releases
[img] https://lh3.googleusercontent.com/-mUlEPiHDOJA/U20G58dLW7I/AAAAAAAAJ_Y/mLeuuBn-z6k/w731-h548-no/IMG_20140509_160415.jpg[/img]


I gave them a quick scrub with a wire brush and they looked a lot better and possibly re-useable.
[img] https://lh6.googleusercontent.com/-HCvqAZDZct8/U20G5y9gL2I/AAAAAAAAJ_Y/Aa-0SBgM-sY/w731-h548-no/IMG_20140509_162238.jpg[/img]


I decided to give them a bath in assorted cleaner fluids to try and get them moving again
[img] https://lh3.googleusercontent.com/-kIc_vMzLDgA/U20G578HOZI/AAAAAAAAJ_Y/Goc910TZX-4/w731-h548-no/IMG_20140509_162447.jpg[/img]


Lots of crud started falling away but I really wanted to shake them up and get the insides clean. I have heard of vibration cleaning tanks where things get shaken about while submersed in cleaner so I thought I would give it a go. Take one orbital sander
[img] https://lh3.googleusercontent.com/-0pIvCY4DG9I/U20G579vpMI/AAAAAAAAJ_Y/xZ27oge3jJM/w731-h548-no/IMG_20140509_163244.jpg[/img]

And one pot of cleaner and dirty parts, put one on the other, switch on the sander and you have a vibrating cleaning tank. I was really surprised how much extra crud came out this way. I also decided not to take the pot back to the kitchen as the bottom was half sanded through!
[img] https://lh5.googleusercontent.com/-hcBTk1W9QF0/U20G58Aj40I/AAAAAAAAJ_Y/07sO_rBZ_04/w731-h548-no/IMG_20140509_163301.jpg[/img]
The end result was what I wanted though. The latches were reasonably clean and after drying carefully, spraying liberally with WD40 and then packing with grease it was time for a coffee break

After the coffee I took the clean(er) and fully functioning latches and started to fit them. Passenger side in first
[img] https://lh5.googleusercontent.com/-djX4VTxpc-Y/U20G597LGHI/AAAAAAAAJ_Y/r1fWT6YmB2Y/w731-h548-no/IMG_20140509_164855.jpg[/img]


I couldn’t get the cable through the enclosed bit of bodywork it was in before but it is now out of the way of the fan and the short length means is won’t get in the way. Don’t bolt the passenger’s side latch in place until you have managed to get the connecting cable back into the driver’s side latch. I found it easier to connect the cable from the car to the latch and then the connecting cable.
[img] https://lh4.googleusercontent.com/-x3pg0Q_1zR8/U20G5_YKK3I/AAAAAAAAJ_Y/yr0NRjXD03w/w731-h548-no/IMG_20140509_164903.jpg[/img]

Grease the bolts and refit
[img] https://lh4.googleusercontent.com/-547WXtuuYG4/U20G5zbKzjI/AAAAAAAAJ_Y/GkSSUyoNafc/w731-h548-no/IMG_20140509_171040.jpg [/img]

You might just want to test that they still work before you fix the pins to the bonnet and close it. I spent ten minutes with the wife sat in the car pulling the bonnet release and me lifting the pins in and out of each side

Pin stuck
[img] https://lh4.googleusercontent.com/-dS6zIKQTP4s/U20G5z_qvMI/AAAAAAAAJ_Y/y4DFnIWqN9Q/w731-h548-no/IMG_20140509_171713.jpg[/img

Pin released
[img] https://lh6.googleusercontent.com/-pBP7jR_9MYg/U20G52KaSQI/AAAAAAAAJ_Y/vxU3kTL52KA/w731-h548-no/IMG_20140509_171727.jpg[/img]


Lots of copperslip in the pins before fitting to the bonnet. Remember how hard they were to unscrew last time? If it ever goes wrong again then it will be easier.
[img] https://lh3.googleusercontent.com/-SMvOvPWWmz4/U20G51j_p5I/AAAAAAAAJ_Y/zUJNilQM9G4/w731-h548-no/IMG_20140509_172136.jpg[/img]

The bonnet catch is sat there waiting for them.
[img] https://lh6.googleusercontent.com/-2vLLXjMyur8/U20G56fSXbI/AAAAAAAAJ_Y/HQOTXvgseUM/w731-h548-no/IMG_20140509_172147.jpg[/img]

Dare you fit them? Will the bonnet stick shut again? Will it all have been in vain?
No!
The bonnet fails to shut at all. In the excitement I had managed to move the locking nuts on the pins so that they were too short to engage with the latches. This is closer to the correct length but it will probably vary between cars. It was a lot easier removing them with the copperslip on though
[img] https://lh3.googleusercontent.com/-8LMYhxWmZVU/U20G5zIlb-I/AAAAAAAAJ_Y/5h_j1RPwTI4/w731-h548-no/IMG_20140509_172758.jpg[/img]

The final task is to wipe off the greasy finger prints
[img] https://lh5.googleusercontent.com/-_jhX48soEk8/U20G5z0NCUI/AAAAAAAAJ_Y/pk5hWpJUnho/w731-h548-no/IMG_20140509_173846.jpg[/img]


I hope no-one else has to go through this. If you own a BMW Z3 please step away from the computer and go grease your bonnet catches. There was no warning that this was about to happen other than perhaps a slight stiffening in the pull on the bonnet release. Go do it now, you do not want to try and release bonnet latches from underneath the car I assure you.

If it does go wrong for you I hope some of what I have written helps