I've had my Sept 2000 M5 for nearly 4 years now and so far I've only had a very few niggly problems that haven't cost the earth, or caused me any great pain to put right, until.... I noticed back in the spring that she didn't feel quite right, but just put it down to age catching up with the car (117,000 miles now) and that I hadn't noticed things changing through the colder months. Shortly after I'd noticed this feeling of age though, I kept getting intermittent episodes of dramatic changes to the exhaust note, but with no noticable drop in power. I'd had a faulty Exhaust CPS before, so was fairly convinced it was that again, but was getting different codes this time - namely B1 Exhaust CPS, B1 Inlet CPS & Crankshaft Correlation Sensor.
I paid for a full GT1 diagnosis and VANOS test just to be sure, which showed Bank 2 (5-8) was fine, if a little noisy, but Bank 1 was utterly shot. The GT1 couldn't even get past the first measurement. Hmmm, I thought - it's not just a 90 quid sensor then! The official diagnosis by Phil Crouch was a failed solenoid unit so I spent £300
and changed it over.
Where it felt almost fine before, bar the intermittent exhaust note change, now the car would barely run. I couldn't understand how changing one part for a newer one could make a problem soo much worse??
Back to Phil and he plugged her back in again and we got 3 pages of codes! He now diagnosed that either the new unit was faulty or that the little gauze filters round one of the solenoid valves themselves had broken up on the old one and clogged an oil channel or two inside the VANOS unit, which would have the same effect. Ironically, I'd probably made it worse by puhing more bits of gauze in when I fitted the new unit.
(This is where BMW would make you by a new VANOS unit for £3,500 or whatever they cost..... I think even a recon'd unit is £1,500)
So I took her in to Phil's again so he could remove the VANOS on bank 1, break it down to its component parts and give it a thorough clean. He'd then re-assemble it with all new seals. It was only due to be 2 hours labour so I asked him to do both sides while he was at it - half the time is taking off the plenum chamber etc anyway, so it seemed sensible. The total, in theory, for both sides to be fully stripped and cleaned would be around £500. I would then have peace of mind that both units were in rude health and be safely fitted with new seals all round.
The car went back in, and after a while I called Phil to see how things were going. He said that B2 was fine and done, but B1 was full of a tar-like goo, presumably from years of oil not being able to flow freely through the unit. This wasn't to be a problem though - it'd just take a little more effort to clean. At least it explained all the problems in one go!
Very excited, I went to collect the car on Wednesday evening just gone, as Phil had finished the clean, given it an oil service, run it up, performed a completely successful test and driven it home. Phew! Happy days are here again I thought......
It had cooled right down by the time I got there, so I fired it up and my heart completely sank. It was worse than ever! The idle was so rough it was almost like sitting inside a washing machine. I drove it to the end of his road and back and it even stalled twice. Not good.
Even though it was late, Phil being Phil, agreed to struggle back to the workshop there and then, where he discovered that one of the tiny wires that powers the solenoids had chafed through on the way home and was shorting on the body of the unit. He sleeved and resoldered it and the idle impoved dramatically, but GT1 still couldn't advance the inlet cam.
We took it all apart again (it's getting pretty late now!) and with a magnifying glass found a crack in one of the tracks on the solenoid pcb. This is starting to drive me nuts!
It must have happened as we took it apart for the 3rd time!
Anyhow, he laid a thin strand of wire along the track and soldered it in place. Now things were starting to sound and feel better and the only thing still failing the test was the exhaust retardation. Since we'd suspected the Exhaust CPS for over 6 months, I agreed to take the car and I'd do the sensor myself on Saturday and go from there.
I'm extatic to say that that went fine and the car is utterly transformed.
I am certain that my Bank 1 VANOS has been gunked up for years, as I have never experienced such awesome torque so low down AND such a desire to rev right to the top. It's like a new engine and the noise coming out of my Tubi Rumore is cleaner, and more powerful sounding - in a cold blooded, menacing kind of way. It's like music to my ears! Don't misunderstand me here, the car's aways been amazing, and between 2k & 6k, it's always been like sh*t off a shovel. It's the 2 extremes that have made themselves so apparent now and across the whole rev range it's smoother, mechanically quieter and more willing to rev. When you blip the throttle now, instead of a rattle and a pause, you hear a huge rush of air into the plenum and the rev counter flicks round the dial instananeously
. On top of that, the odd idle and wandering revs at parking speeds that I put down to age, have completely gone. The difference in the way the engine feels is like the difference between your head with a hangover and the way you feel after a billiant sleep on the weekend. (Sorry, but I can't think of a better way to desribe it!)
I thought my aging beast was getting long in the tooth and I'd have to nurse her along to the end, but how wrong I was. All she wants now is to be grabbed by the scruff of the neck and driven like she's been stollen. I pushed her hard this weekend and all she wanted was MORE. I have to say I feel the same way.......
Total Bill, including the arguably unnecessary solenoid unit, all the peripheral seals etc, CPS, fuel back an forth, tests and service, was near enough £1200. In my mind, for a car of this calibre, that's a very small price to pay for peace of mind, a mile wide grin and chills up your spine very time you drive it (or even just think
about driving it!!)
I'd like to thank Phil for not letting this get the better of either of us, not counting the hours too closely(!), and to Kumaran (M5 London) for all his help with the DIY bits and bobs. Big thanks also to all those on the board who helped out with all my questions leading up to this over the last few months.
I hope this thread may ease the fear that some M5 owners like me, have/had about VANOS failure, and give a few pointers to those with odd problems out there. I've bored you with all the gory details here, as it shows that there really isn't anything you can't fix on these cars if you have the inclination (or know Phil!) and they aren't as expensive to run as some would have us believe...... They are just the greatest cars in the world.