Monday 28 January 2019

When a roof falls on a 4 Series...

As if the aftermath of the high winds across the UK this weekend was not bad enough with roof tiles downed and half my barbecue making its way over to next door's garden, I was then called to one of our sites this morning to help lift the forecourt roof off of a customer's 2016 425d...

The bonnet/hood took the brunt, but the rear window has smashed too and, considering nothing hit the glass directly I would assume that just the shock of the massive impact to the front of the car caused it to shatter. Must have made quite a bang...

Considering the size and weight of the metal awning that collapsed I think the Beemer took it pretty well... car is atill driving ok... still, I wouldn't like to be the member of our Service department who had to call the customer this morning and tell them...

Sunday 20 January 2019

F10: Clutch Bleeding Guide... the whole nightmare! [Manual transmission / gearbox 520d, 530d, F10, F11, G07, E90, E92 3er etc.]

You will need:

  • Short / stubby ... wrench.
  • One-way valve type bleeding-kit.
  • DOT4 regular brake/clutch fluid.

Clutch-bleeding on the F10, F11, G07, E90, E92, G20 and a lot of other contemporary BMWs can be a right pain, but if you are replacing the master-cylinder / slave-cylinder, the pipework or removing your CDV, then it is necessary. If you clamp the clutch-hose by the slave-cylinder and don't allow a lot of air back into the system, then bleeding should be pretty straight forward, but if a fair bit of air does get back into the system or you are removing the master-cylinder then it can't be helped and a full bleed is needed. The trouble with a full bleed is that these systems are notorious for air locks, primarily in the master-cylinder, which can be tricky to dislodge and get fluid into.
The main drawback with a regular bleeding process, where the bleed-nipple is opened as the clutch is pumped, is that the bleed-screw is located half way up the transmission tunnel and very difficult to access with a wrench. This makes it difficult to quickly shut the bleed-valve, which is kind of essential for this process and air can get back in. If you are able to access the bleed-screw without difficulty or have some special tool designed for the job then regular clutch bleeding should work a charm with air locks and, though it may take a while, you will be on your way.
A pressure-bleeder may give the time needed to tighten the fiddly bleed-screw, but does not work to get rid of air locks and seems to bypass the master-cylinder completely, so I would avoid using one of these kits at all if there is a lot of air in the system. Some trapped air at the top of the system seems to want to exit through the reservoir anyway, so it's better not to cap it with a pressure-bleeder as it just does not seem to want to go with the flow. If you clamped the hose and only the slave-cylinder needs bleeding then a pressure-bleeder should do that in no time.
I found that a one-way valve bleed kit was the way forward. It prevents the return of air/fluid while the bleed-screw is left open and gives time to shut it when the process is complete. It leaves the reservoir open to be manually topped up, which shows precisely how much fluid is entering the system. This was the key, for me, to finally shifting the stuck air from the master-cylinder.

I have detailed the various techniques and problems below:

Location of Brake + Clutch Reservoir:

The brake/clutch reservoir is not very apparent in the engine-bay. It is located under the black panel in front of the windscreen on the driver's side of the car. Looking from the front, left-side for RHD cars and right-side for LHD. The opposite panel covers the climate-control entry-ducts.
The panel is held in place by 4 plastic clips, which can be removed by prising up the centre of the clip and then prising the base of the clip out with a panel-popper / trim-tool or a couple of flat-screwdrivers.
The fill-neck for the reservoir is right under the bonnet-hinge and pouring DOT4 in without spilling it can be tricky, so a funnel is a good idea when topping-up. I would recommend putting a towel around the reservoir also, as brake-fluid is not a nice thing to get everywhere and it is easy to over-fill. Special care should be taken when replacing the cap - the large plug that hangs under the cap will surely displace some fluid over the top of the reservoir as the cap is dropped in.

Bleed Nipple + Regular Bleeding:

Unlike BMWs of old, the bleed-nipple on the slave-cylinder is way up in the trans-tunnel and difficult to access with a regular spanner. Getting the spanner onto the bleed-screw is not a problem, but if the spanner has any length to it then no more than a few degrees of turning is possible and the valve cannot open enough. A short spanner, the one I used was about 4.5 inches long, has just about enough room to get the bleed-valve open a half-turn or more, but it is still a fiddly process, particularly with the car on low ramps and quickly shutting the valve can be tricky. This can allow air to get sucked back in before the valve is closed fully, as below.

Air Getting Sucked Back / One-Way Valve:

With only a few seconds to shut the bleed-nipple before air gets back in, I found the best solution to be a one-way valve bleed system. These are basic, widely available kits and just have a valve with a ball-bearing in the end, which sucks back and blocks the tube so no to air or fluid re-enters the bleed-nipple after each clutch stroke. At the least it makes the return of air and fluid very slow and that gives the vital time needed to shut the bleed-screw.
I used the Vizilbleed branded kit, left in the pic, and it worked brilliantly, with a soft rubber hose to fit over the nipple and a plastic collar that slides over it to make a tight seal. It also has a built-in bottle to catch fluid and, though the tube could do with being a bit longer, the kit is a bargain at £7 from Halfords. The kit on the right in the picture is even more basic, just a tube with a one-way valve at the end, but I am sure it works just as well. This Halfords branded kit was dearer at £10, but kits like these can be bought from eBay and Amazon for less.
The clutch takes a lot of pumping to get out air stuck in the master-cylinder next to the pedal and the fluid level in the reservoir needs topping-up constantly to ensure it properly fills. The section of reservoir dedicated to the clutch fills from quite high up in the bottle, so when topping up make sure you fill into the neck of the reservoir.
The one-way valve will prevent air getting back in, so the bleed-nipple can be left open and I found the best technique was to pump the clutch-pedal about 20 times, then top-up the reservoir. The level in the reservoir after the first 20 pumps should drop significantly and continue to draw more fluid after it is first filled, so make sure it is topped right up before pumping again. This should not take more than 2 or 3 goes and I found the amount of fluid that bled out of the slave-cylinder was less than I had poured in, meaning after a couple of failed bleed attempts I had finally got that stuck air out of the system.

Pressure Bleed Kit + Air Locks:

If you have clamped the clutch-hose and don't have a lot of air in the system or any air locks, then a pressure-bleed kit should work as normal. These kits, such as the Gunson Eezi-Bleed, work by pumping fluid in using air-pressure from one of the tyres. Problem is, if you do have air locks, particularly air in the master-cylinder by the pedal, then a pressure-bleed will not work to get rid of them. I found that the kit would just pump neat fluid directly through the system, giving the impression of an air-free system, but still leaving the master-cylinder full of air and no clutch-pedal. Even pumping the clutch while pressure-bleeding did not seem to clear the trapped air, I think because it wants to exit the system from the open reservoir and has been pushing against the incoming fluid pressure.
A 'reverse' pressure-bleed kit that builds up a vacuum and sucks the fluid through bleed-nipple as it is topped-up from the reservoir might be effective in getting rid of air locks, as the reservoir remains open and the fluid/air will be pulled down from the master-cylinder, rather than pumped straight past it, but I did not have chance to test one.

Back Filling + Clutch Delay-Valve (CDV):

I have seen many articles discussing back-filling of the BMW clutches to be the easiest way to clear all air from the system. This works by injecting/pumping fluid in through the bleed-nipple using a syringe or suitable pump and ejecting the air out the top of the reservoir. While this may work great for older models, modern BMWs have a slow-return valve fitted before the slave-cylinder [pictured]. This is known as the 'CDV' or Clutch Delay Valve and works by slowing the return of fluid to the master-cylinder when the clutch is engaged. This makes it impossible to dump the clutch too hard, as it ensures a nice soft engage every time. Flow from the master-cylinder to the slave-cylinder is unaffected, so the clutch releases as quickly as you like, it is just when fluid returns that it is slowed down. This is all wonderful technology, but throws its hand in when trying to back-fill the clutch to bleed it as you are pushing against the CDV.

Sunday 13 January 2019

F10 530d: Clutch Replacement [Manual 520d, 530d, 535d, F10, F11]

The clutch on my F10 has felt like it's on the way out for about a year now and over the last month or two I've noticed it starting to slip a few times, mainly when moving off in first gear with the car pointing uphill. Time to throw a new clutch in, one of my least favourite jobs and just as with everything on the 5 Series, way more involved a process than swapping a clutch into a Ford Focus. Even I was tempted to just leave the F10 with someone to do the clutch for me, but with quotes in the £1000 - £1500 range I figured it was better to bite the bullet and do it on the drive. Just as well too, as you can see from the pics to the right just how far gone the clutch was, with hardly any face left on the friction-plate and some lovely hot spots on the pressure-plate! Nice.
I'd love to say this job is the same as the E39/E60, which are pretty straight forward, but it is trickier due to updates in the car's design. The main difference is in the prop-shaft removal, the F10 requiring the rear gearbox-mount to be removed to access the bolts to the coupling. This makes it almost impossible to move the car to rotate the prop and access the top bolts, so a bit more ingenuity is needed. I also notice that the gearbox must be lowered in order to remove the slave-clyinder, which is wedged up in the trans-tunnel, something that was not necessary on the E39 and E60. The hose to the slave-cylinder also needs to be unplugged and fluid drained so the gearbox can be lowered. This is an added annoyance that BMW have engineered in here.

** Before you undertake this job yourself, it should be understood that 5-ers are complicated cars and a lot needs to be removed before the gearbox / clutch can be accessed. This is a short list...
  • Main under-tray and both side trays.
  • Exhaust.
  • Two heat-shields.
  • Brackets.
  • Rear gearbox mount and bracket on back of gearbox.
  • Propshaft coupling and centre-bearing.
  • Starter-motor.
  • Hose to slave-cylinder. [inc. refilling and bleeding of clutch].
  • Only now can you remove the gearbox and swap the clutch...
But hey, if you have made it to this guide then chances are you aren't fazed by this kind of thing! So read on... the whole job can be done at home over a weekend by yourself, taking your time and enjoying yourself... or could be done in one day by two of you...


** Disconnect the battery negative-terminal and put it safely out of the way. **

1. Remove the front belly-pan under-tray located below the engine and gearbox. It is held in place by 8mm screws all around the edges and a couple in the middle.

2. Remove the left and right middle under-trays. These are located under the sill on each side and held on by a lot of 8mm screws and some plastic clips.

3. Remove the centre cross-brace by undoing the eight 13mm bolts, four on each side. This is a steel plate that runs across from left-to-right near the back of the prop-shaft.

4. Remove the exhaust up to the down-pipe. First loosen the 16mm nut on the flange connecting it to the down-pipe at the front. There are then two rubber-hangers, one next to the rear-axle and one to the front of the back-box. A third rubber-hanger is located to the front of the exhaust, not far back from the down-pipe and this can be separated on its bracket by removing the two screws using an E10 double-hex (female-torx) socket. Finally there is a 13mm nut holding a bracket at the very back, up inside the rear-bumper. The exhaust can now be carefully lowered [watching the rubber-bush that has no purpose on the right of the back-box does not get caught in the bumper], worked free of the flange on the down-pipe and fully removed. If the car is high-up on a lift then you will likely need a second person for the last bit.

5. Remove the main heat-shield located above the exhaust. It is held on by several large, flat metal nuts that can be loosened with a 10mm wrench and then spun off by hand.

6. Remove the aluminium bracket that sits around the centre-bearing of the prop-shaft by undoing the two 8mm bolts holding it to the bearing and wiggling it free.

7a. Place a jack or suitable stand under the gearbox to support it so the rear mount can be removed. 

7b. Remove the rear gearbox mount by undoing the three 13mm bolts on each side holding it to the car and a single 13mm nut in the centre that holds it to the rubber-mount on the gearbox.

8a. Remove the braided electrical-earth strap at the back of the gearbox by undoing the 13mm nut attaching it to the body.

8b. Remove the bracket at the back of the gearbox that attaches it to the rear mount, by undoing the four bolts using a T55 Torx socket. Make sure the socket has good purchase here, as it can slip out easily and round the edges of the bolt-head.

9. Remove the 3 bolts holding the prop-shaft coupling (donut) to the back of the gearbox using an 18mm wrench on either side of the nut/bolt. The bolts on the upper side of the prop-coupling are difficult to get to up in the trans-tunnel. If the rear wheels are not lifted and the prop cannot be turned to get to the bolts, it is possible to get them with CV-joint type sockets as I did.

10. Undo the bracket holding the centre-bearing of the prop-shaft by removing the 13mm nut either side.

11. Uncouple the prop-shaft from the gearbox by pulling the centre-bearing down enough for the locating pin on the gearbox to be clear of the prop-coupling. The front of the prop can now be lowered and moved to the side. If you have the whole car raised on a lift, then you will need to support the front of the prop, or remove the rear coupling to the diff. and get someone else to help you lift it down.

12. Remove the live terminal from the starter-motor using a 13mm wrench and the earth-terminal using a 10mm wrench.

13. Remove the 3 screws holding the starter-motor to the engine using an E10 double-hex socket and work the starter-motor out from the gearbox.

14. Disconnect the reverse-light switch by depressing the metal wire-clip to remove the plug and unclip the wire along the gearbox.

15. Clamp the rubber-hose to the clutch slave-cylinder and disconnect the clutch-line where the slim metal tube enters the slave-cylinder. This is done by prising the metal-clip out of the connector with a small flat-screwdriver and pulling the rubber-seal out of the slave-cylinder. Don't worry too much if you cannot clamp the clutch-hose, but it will involve more bleeding later on, which is a nightmare.

16. Remove the four bolts from the lower half of the gearbox bell-housing attaching it to the sump using an E10 double-hex socket.

17. Remove the remaining 6 large bolts from the gearbox bell-housing holding it to the engine-block using an E12 double-hex socket. [As in diagram.The 2 down each side of the bell-housing are easy enough to access, but the 2 at the top are quite tricky. There is no easy way to get them, so it might be worth feeling around the top of the gearbox with the socket only until it is on the bolt and then get the ratchet / extension bar or CV-jointed socket to them.

** CAUTION: The gearbox will now be loose and held to the engine only with the locating-pegs, so ensure it is safely supported! **

18. Gently prise the gearbox away from the engine until it is clear of the locating-pegs and held up only by the centre-spline. Rocking it side-to-side should also help here. Draw the gearbox back slowly until the centre-spline is clear of the clutch/flywheel and the gearbox can be safely lowered partially. ONLY LOWER IT ABOUT HALF WAY!

19. Disconnect the wiring-connector from the cars neutral-sensor, located at the top of the gearbox by reaching around the top while it is partially lowered and pressing in the plastic clip on the connector. Fully lowering the gearbox before disconnecting will stretch the wire and potentially snap it!

20. Fully lower the gearbox safely onto the ground.

21. The clutch is now accessible, bolted to the back of the flywheel at the back of the engine. The clutch is removed by undoing the 6 bolts around its circumference using a 6mm allen-key socket [shown in photo]. The clutch can now be prised away from the engine! Be careful the clutch does not drop at this point, so it is best to support it with one hand while loosening the final bolt.

22. Remove the release-module / bearing from the spline inside the gearbox bell-housing. The metal lever should be held in place on the opposite side to the slave-cyinder by a piece of metal-wire and after removing that it should easily pull off. [If your clutch-kit includes a new release-module that is - if you are not replacing this then leave the old one in place.]

RELAX! You are now half way through the job!

23. Clip the new bearing into the new release-module as per the clutch-kit instructions and refit it to the spline in the gearbox bell-housing, replacing the wire-clip.

24. Fit the new clutch friction-plate into the new pressure-plate and mount it to the back of the engine leaving the 6mm allen-bolts loose by a few turns so the friction-plate can be moved around inside, but will hold in position.

25. Use the correct clutch alignment-tool to centralise the clutch, or if you do not have one look directly into the centre bore of the clutch and centralise the friction-plate by hand. It does not have to be perfectly in the centre, so you can get it accurate within about 0.5mm by eye.

26. Fully tighten the 6mm all-bolts.

27. Partially raise the gearbox to leave a few inches clearance above it and reconnect the wire to the neutral-sensor.

28. Fully raise the gearbox so it is in line with the back of the engine and move it forward, guiding the centre-spline into the clutch. Rocking the gearbox left-to-right should locate the spline into the clutch plate without too much fuss and it should then be able to rotate into position to meet the locating studs. The main problem here is the height and pitch of the gearbox on the jack / gearbox-stand, so watch out for differences in the gap at the top and bottom of the bell-housing when marrying it up.

29. Reverse steps 17 to 7. For tightening-torques refer to this post -

30. Bleed the clutch - if you clamped the hose you shouldn't have too much trouble bleeding it, but the nipple is difficult to access and it can be easy to let air back in, so I have devoted a post to my bleeding issues here - F10: Clutch Bleeding Guide... the whole nightmare! [Manual transmission / gearbox 520d, 530d, F10, F11, G07, E90, E92 3er etc.]

31. Reverse steps 6 to 1.