Swirl-Flap Failure - DIY Cheap Fix

I managed to fix my swirl-flap issue and rebuild the original engine for £500, on my driveway, without raising the car or removing the entire engine bay. I wouldn't recommend it for a novice, but if you are the kind of person to run these cars on a tight budget then you probably have some grounding in car maintenance and can do it at home without shelling out that £1500 for a new engine or £3k+ repair bill.

** If you can afford to have this done professionally, or still have some kind of warranty on the car then go down that route. This is not a quick fix to get the car up and running again in time for work, it involves a near full top-end rebuild and reusing damaged components is never going to be as reliable as fitting new ones, so don't blame me for any further damage to the engine! **


1. Diagnosis - Removing the Inlet-Manifold
  1. Loosen the jubilee-clip on the EGR-pipe, to the left of in the air-intake pipe from the intercooler, until it can be freed and rolled off to one side of the pipe.
  2. Remove the air-intake pipe from the throttle-body by pressing the top of the metal-clip up with a flat-screwdriver and pulling the pipe towards the radiator.
  3. Fully loosen the 12 bolts holding the left side of the inlet-manifold using a 10mm socket.
  4. Remove the 7 nuts holding the main intake-pipes on the manifold to the studs on the head using an 11mm socket. The last one is located down the back of the head, in line with the others.
  5. Lift the inlet-maifold off the studs and unclip the large rear wiring-connector, as well the smaller connector to the swirl-flap solenoid by pressing the metal-clip up with a flat-screwdriver.
  6. Pull off the small vacuum-hose running to the diaphragm on the throttle-body and the one running to the swirl-flap solenoid.
Inspect where the main inlet-pipes join the head. The swirl-flaps should be in the open position just inside. If one is missing then you know where it's gone... My no.4 came off and was blown back into the intake-plenum, wrecking cyls. 4, 5 and 6!

2. Removing the Cylinder-head (Simplest Method):
  1. Remove inlet-manifold as above.
  2. Remove the wiring-connectors from the mass-airflow sensor, camshaft-sensor, fuel-rail, ... and all injectors.
  3. Remove the injector-pipes and main fuel-pipe from the injectors and fuel-rail using a 17mm open-end spanner.
  4. Remove the fuel-rail by undoing the three bolts along the side of the head using a 10mm socket.
  5. Remove the nut holding either side of each injector down using an 8mm deep socket, preferably a 6-sided one as the nuts strip easily with a 12-sided one.
  6. Using a large flat-screwdriver, gently prise each injector out of the rocker-cover and slide off the metal collars that hold them down. There is no need to disconnect the braided leak-off pipes along the top - all the injectors should come out like a string of sausages and be move over to the right. [Inspect the injector-tips for damage.]
  7. Remove the twelve studs that hold the injector-collars onto the rocker-cover using a 10mm deep socket.
  8. Remove the captive-bolts that hold the rocker-cover to the head using a 10mm socket and lift off the rocker-cover.
  9. Remove the bolt from the cog and gear wheel of the inlet-camshaft using an E12 double-hex or star socket. 
  10. Pull the chain and cog wheel away from the camshaft and remove the plastic guide-rail from inside the right of the chain. Now the chain is loose, roll it off the cog wheel and remove the cog wheel. 
  11. The tensioning-rail should now be removable from inside the left of the chain and the chain-tensioner will spring completely out and the chain can be lowered into the head. [You can push the chain-tensioner back easily after the head is off, but refitting it is nigh on impossible after the head is put back!]
  12. Remove the 3 bolts holding the vacuum-pump to the front of the exhaust-camshaft using a 13mm socket and remove the pump.
  13. Remove the bolt holding the vacuum-pump sprocket and gear wheel to the exhaust-camshaft using an E12 double-hex or star socket and remove the sprocket and gearwheel.
  14. Working inwards from the outside, remove the 14 screws holding the cap-caps over each camshaft using a T30 Torx socket and remove the caps and camshafts.
  15. Remove the exhaust-manifold by undoing the twelve nuts that attach it to the head using a 10mm 6-sided deep-socket, [copper washers strip with a 12-sided socket], and the three bolts holding it to the turbo using a 12mm twelve-sided socket, or 13mm 6-sided one.
  16. Remove the bolts holding the front of the cylinder-head to the lower timing-case using a 6mm male-hex or allen socket. One is right under the timing chain.
  17. Remove the 14 cylinder-head bolts using an E12 double-hex or star socket using a reversal of the tightening order below, from 14-1.


3. Repairing a Damaged Piston:

Any piston affected by a swirl-flap going in is going to be well battered, but as long as there are no holes in the top and the 'swirl-pot' is still intact, as in it is still in shape and no large cuts in the side of the pot, then it will still fire and can be re-used.

** I would advise replacing the piston as a matter of course if you have the facilities to do the work. The parts will not break the bank and if the piston isn't destroyed it can always be reground anyway, but removing it involves a huge amount of extra labour. First, the plastic under-trays need to come off, then the metal one that sits above them. Next, the cross-members and engine-mounts, so the gearbox needs supporting on a jack. The sump then comes off with the big-end shell for the affected piston and, finally, the piston is knocked out of the top of the block with a hammer and piece of wood. For this, the car will need to be lifted a good way off the ground, ramps I think are essential. I was on gravel and couldn't move the car, so this job was out of the question for me. I went with the quick and very dirty method of re-grinding the piston while it was still in situ, slightly down the engine-block. If you can be bothered doing the work, but not spending the cash, removing the damaged piston to be reground properly would be better than doing it in the block. If you're comfortable with this, see this post - E60: Engine Rebuild 2 - Mashed up piston re-grind - ghetto style...


4. Locking the Chain-Tensioner:

** This is best done while the cylinder-head is still off the car, as accessing the tensioner is very difficult when it is back on.

  1. Remove the front-plug for the chain-tensioner using a 17mm male-hex socket. [It is located just under the belt, where the allen-key is sticking out in the pic.]
  2. Slacken the nut located just inside the chain-tensioner, accessed through the plug recess, using a 10mm deep socket. This releases oil-pressure and allows the tensioner to be pushed all the way back in.
  3. Push the spring and cylinder back into the chain-tensioner, using a large flat-screwdriver or similar and insert something that resembles BMW's 'Special Tool 11 3 340' into the small sleeve in the tensioner, via the plug recess, as in the pic. [I used a 3mm allen-key which worked perfectly, though anything long enough will do, although if it is too thin the tensioner may spring back out.]
Pressing the cylinder back in is so much easier while the head is off, above. It's a good 8-inches deep when the head is on, though refitting the tensioner is just about possible.
Here is a condensed version of the locking and unlocking of the chain-tensioner from BMW TIS:


























5. Refitting the Cylinder-Head:

If you are comfortable with what you are doing, just tighten the head-bolts in the sequence shown in the pic below from 1-14, using this torquing sequence - 80nm, loosen all bolts 1/2 turn, 50nm, 90 degrees, then wait a bit and turn them another 90 degrees.



The complete guide for refitting the cylinder-head from BMW TIS can be found in this PDF [RA Removing and installing Cylinder Head (M57TU).pdf], which includes the tightening sequence and references to the tightening-torques that can be found in the image below.



6. Refitting Camshafts and Retiming:

The complete dealer process for refitting the camshafts and retiming the engine using all the special tools can be found in this PDF from BMW TIS [RA Replacing camshafts (M57TU).pdf], with references to tightening-torques mentioned in the images below.

If the crank remains in position then there is no need to remove the lower portion of the chain from the bottom cogwheel. The lower chain-tensioner will hold it in place. For the ultra quick and easy guide on how to retime the engine this way, without any special tools, see this post -  E60: Engine Rebuild 3 - Camshafts + Re-Timing - ghetto style...




7. Fitting Swirl-Flap Blanking Plates:

** Some say the engine won't run properly without the flaps, but I am assured it will and for a lot longer. All the swirl-flap is designed to do is to dump air into the engine when the inlet-pressure is reduced and soot would normally be dominant. In other words, it reduces the little puffs of black smoke on harsh gear changes. The car will still pass MOT and won't use any extra fuel.

See this post for the how-to-guide and fitment info. - Swirl-Flap Blanking Plates.

1 comment:

  1. Hi,
    Great post but having read many articles on the subject of swirl flaps I could not understand why everyone buys the blanking plugs.
    I bought a 525d and immediatly stripped out the inlet manifold and sure enough they were in poor condition. I simply removed the flaps, and their mechanism and removed the flaps from their plastic circular mountings. This left me with the now empty shaft holes. I used an M6 tap (begged, borrowed or...) and tapped the holes to about half way down then screwed in (from the OUTSIDE) M6 10mm headed bolts with a little loctite on the threads. The purpose of only tapping to halfway was to provide an interference fit. I've now done over 30k miles on this zero cost fix and of course there has been no problems. I can also confirm that the car drives just as well as before the swirl flap removal.
    Chrisr

    ReplyDelete