Friday 24 October 2014

E60: Split Vac-line, some boost, weird noises.

The turbo whine and lack of boost has persisted, so I took off the inlet-manifold again to check the vacuum-lines and found one has snapped off. Luckily, there was plenty of hose left to cut it down and push it back onto the T-piece. I re-checked every line twice against the diagrams on and refitted the manifold, making sure the seals were super flush. Now when I fired up the turbo started making a ridiculous whoosh and dump-valve style hiss, as in the vid below. Some boost had returned too, though not as much as there should be and certainly nothing like the turbo sounded. Still, the vac-line repair did get a result, so it looks there could be life in the turbo yet.

There was nothing else I could do other than pore over the vac-line configuration, so I made this quick one-piece diagram to show the route of the four coming off the servo-pipe to save switching between several diagrams on RealOEM. I then started pulling vac-lines off in order to find the faulty area and, amazingly, managed to get rid of the whoosh/hiss and still have some boost. The turbo is still whistling though and there is not enough pull as you get over 2k rpm, so something is still amiss.

  • Split vac-line to swirl-flaps - Low boost, quiet turbo-whistle higher up.
  • Repaired vac-line - Some boost low down, cuts out higher up. Loud whoosh and hiss noise, turbo-whistle constantly.
  • Vac-hose removed from wastegate - Low boost, quiet turbo-whistle higher up.
  • Swirl-flaps and engine-mount vac-lines switched round - Some boost, no whoosh/hiss, constant turbo whistle, less engine vibration.
The diagrams do not make clear the route of the red/black striped hose on the right of mine. This turned out to be the N/S engine-mount and another scan of revealed how they work in the pic below. I had wondered about a problem with the engine-mounts anyway, as there seems to be a lot more engine vibration than before, especially on tickover, so my next job will be to find the pipes that link the mounts together and check their condition. They all run through the subframe next to the steering-rack. M57N is a complicated vacuum arrangement.