E60: Horrible dash rattle - loose Strut Brace.

If there is a loud rattle from behind the dash on your E60, the sound of two plastic surfaces creaking against each other like tectonic-plates, or a cracking noise that sounds like the windscreen is flexing, then the strut-brace is loose. 

This is the alloy bar that bolts across the front suspension turrets and also to the firewall in the middle, which cuts down on chassis-flex as the front wheels move around. The E39 didn't have one and the E60 doesn't need one, but it's there and if one of the bolts come even slightly loose then it produces a rattle inside the dashboard like no other. It is not easily identifiable as a loose component in the engine-bay by ear as the noise is so internal and you may find yourself, as I did, spending forever adjusting panel fit inside the dashboard and cable-tying wire connectors with no joy. Rest assured it is a loose bolt on the strut-brace.

The problem is steel bolts going into alloy threads on the strut-tops, which become loose easier and are more prone to damage if overtightened or the strut-brace is removed and refitted a lot. BMW are aware of the problem and they're official fix is detailed in this PDF [http://5series.net/forums/attachments/e60-discussion-2/37844d1190387791-cracking-sound-e60-dashboard-sib_511304.pdf], but they will charge a premium for this and probably replace the brace.

The strut-brace attaches in three places, with two bolts in the centre joining the firewall and one either side on the strut-tops. They have E10 double-hex heads. Two of my four bolts were loose - one of the centre ones, which just kept spinning and needed coaxing out, and the O/S strut-top. This would get near tight then skip and go finger-loose again. The strut-brace was so loose this side that it could be moved around by hand at the end with the bolt in place.

Quick Repair Options:

• Heli-coil - This is the recommended or 'pro' way. You can get a hell-coil kit for £10-£20 and it basically winds a new stainless-steel thread into the old one so the original bolt tightens straight back in.
• Drill out and re-thread - This is cheaper and dirtier as it just involves boring out the hole with the damaged thread to a larger size and using a die to re-thread it to accept a larger bolt. This is what I did, drilling the offending hole in the O/S strut-top out to 9.5mm and threading it using an M10 tap. I then used a short M10 bolt (17mm) with a large knurled collar to keep that end of the brace nice and tight.

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This did NOT fix the rattle?

If you're strut-brace is not loose and the noise is still there then it could be two other things:

• Axial tie-rod / Track-rod end failing - Yes, when the axial tie-rod / track-rod ends start to fail it does produce a rattling / cracking noise from behind the dash, just like a loose strut-brace. No one would ever guess this defect would make this sound where it occurs, but there you go. I suspect this was the cause of the rattle in my E60 after all, though never had chance to replace the part before I sold it and the guys buying it both agreed the noise was something steering-rack related. 
• Loose trim - If the sound is definitely originating behind the dash then loose trim or structure is likely your culprit, though this is quite rare. E60s use alloy design and the body absorbs a lot of flex, so when stuff behind the dash does become loose the sound is amplified in the cabin. I am sure when this does happen, every case is different so there is probably a lot written about it online. Best of luck tracking it down. 

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This is a common fault and there is plenty of information on the forums:

http://5series.net/forums/e60-discussion-2/cracking-sound-e60-dashboard-45017/

http://www.bmw-driver.net/forum/showthread.php?t=44948

http://forum.bmw5.co.uk/topic/80790-a-slight-knocking-noise-from-the-dash/

http://forum.bmw5.co.uk/topic/17634-rattle-from-dash-on-start-up-from-cold/

E60: Update + New Turbo!

Right, now the E60 is back on the road and all legit it's time I fine fettled the engine-vacuum and rattling exhaust issues left from the engine swap. The exhaust needs realigning at the back of the turbo so it doesn't contact the bracket and the vibration-dampers can be set correctly. The only way to do this is to first remove the rocker-cover and injectors and after my injector-seal problems with the new engine I haven't been able to justify doing that unless it's really essential and that time is now.
The culmination of all my messing around with the vacuum-lines [from this post] is a partly-boosting turbo that sounds like a police-siren. From the word go I was told this is the key sign of a broken turbo, but just couldn't believe it as the turbo seemed to be working ok after the initial engine rebuild (or was it?!) and the other vacuum niggles gave me false hope that it could be a cheap, easy fix. I should have learned by now that this is never the case and have now come to the conclusion of a glaringly obvious broken turbo. I guess that swirl-flap destroyed every part of the motor that it passed through, so lets hope and pray, seriously, that I don't have catalytic-converter issues in future.

So here is my replacement turbo. It's from an E65 730d and was the only used turbo I could find that fits my 'vacuum-actuated' setup, rather than the later and far more common 'electronic-actutor' type. I got it for the spiffing price of just £200, including delivery, but alas there is another catch - the front casing is dented at the outlet-port to the intercooler and the alloy has cracked, maybe during transit, but probably in the crash that wrote-off the 7-Series. This isn't a major setback though, as the front casing just bolts on and is a dry fit, so should not be much drama to swap the cleaner casing from my turbo onto this one. It also plays no part in the functionality of the blower, so if the mechanism works then it works. I'm no turbo expert but there is less play in the spindle than my current blower so if it cures the problem it will have definitely been worth the extra effort for the knock-down price.

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 RealOEM.com 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 RealOEM.com 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.

E60: Turbo whine and no boost!

With the engine-swap teething problems put to rest and the car back on the road [at last!], there was bound to be a few running faults. All in all its going like a dream, though I would say the engine is a lot noisier and vibrates more than before. This could mainly be due to the lack of acoustic-covers and under-trays as I iron out defects, but not entirely so I will have to look at the pneumatic engine-mounts when I have time.

When I got the car out for a good run, the main problem I notice is a serious lack of boost. The turbo is also making a low-pitch whining noise, which sounds a bit like a police siren. I read that this is the noise of a dying turbo, though I find this a little hard to swallow as it was fine before and I see no reason how being removed from the car for 3 weeks would affect it. Far more likely that I've messed up attaching some vac-line or wire-connector, or lets hope so anyway. It's an annoying whistle, as it can only be heard while driving under load and not when revving at a stop.

• Turbo can be seen spinning.
• No front-rear play on spindle-shaft, hardly any left-right play.
• Pipes from turbo to intercooler and intercooler to inlet OK.
• Removed and cleaned air-temp. sensor.
• Some boost air is coming from the intercooler outlet.

Before I diagnose a dead turbo and start spending any more money, I will check the vacuum lines meticulously and also re-check the pipes for splits. The turbo also needs looking at, from the oil-feed to how it's fitting the manifold. The waste-gate doesn't seem to be operating and that seems a bit too serious to be caused by such a small vac-line fault. Ho hum, the saga continues...