Now back to the VANOS. When I drove a friend's Z4M back to back with mine, I had a slight impression his car was more responsive or faster than mine - at the time I put it down to the intake he has or just perception of speed with very different exhaust volumes. I always thought that the S54 was characteristically weaker down low to not compromise the top end (ie relatively high lift cams to breath at 8k). Rebuilding the VANOS was always on my list, but I had no real rush to do it as I had inspected the exhaust hub tabs during the last service and it passed all the ISTA tests.
I had far too much time over winter to read about bolts coming loose, guides breaking etc, so I got pretty neurotic and decided to do a lot of preventative maintenance before summer when I know the car will be seeing a lot of high RPM. I ended up ordering all the bits I thought sensible from Hack Engineering just for ease of getting everything from one place - worth while for the sake of £20-30 one would save by going with various sellers for all the individual bits. What I ordered:
When I received my order from HE and saw that their 'upgraded' sprocket bolts were A2-70, that did not feel right to me. In short, do not use that, go with 8.8 as spec'ed by BMW. More on my thread on
M3cutters.
Here's where my VANOS unit sat for a week as I did some work on the engine itself and got the oil pump disk re-drilled:
I got the oil pump drilled by someone at work. Which meant I had to CMM the part and CAD it up, so feel free to use this if you want to go via someone other than Hack Engineering and their £100+ fee:
Here's the before and after of the re-drilled oil pump disk:
[youtube]UaYhD7sb4m4[/youtube]
It wouldn't be me if I didn't polish it up and improved it a tad. Test piece:
Cleaned up unit:
Exhaust sprocket removed to give me access to the chain tensioner guide. It doesn't matter how confident I feel, messing around with timing chain of an engine that costs £6k to rebuild is quite stressful:
Old vs new. Probably wouldn't last much longer before the end snapped:
The 'VANOS guide' was not bad at all. Just polished a tad. You see some horrific wear pattern in some cars (ie two deep grooves almost), but I guess my chain didn't feel or look like it had any noticeable stretch, it looked/felt exactly the same as the new chain
Mr Vanos fitted to this E46 M3 CSL at 4:30s
My cam bolts were all tight and consistent, thankfully. But I installed new bolts with Loctite 243 and torqued them to 12Nm.
What really made me nervous about this job is getting the timing correct. You can't mess it up massively, but you can have it slightly out and have to take it all apart to correct it. The sequence which you have to pre-load the hubs made me quite nervous as I wasn't sure I would be able to torque the bolts once the VANOS unit was in place. Although I have good feel for tightening bolts, when I'm dealing with engine internals, I would feel very neurotic about doing them by feel alone. Thankfully I used one of these extenders with my torque wrench and it worked really well. Also tested it with the torque tester at work and I was getting 14N/m +/- 3% consistently.
As I turned the engine over, I kept checking timing both with the bridge you're supposed to work with and the timing check tool. Timing was bang on every time and I was a happy man.
According to the label on the Beisan seals, it takes about 200 miles for them to bed in properly and full performance to be achieved. But as soon as I drove out of the garage I noticed an improvement. I rev my car up to 3k until it reaches 90deg oil temp and only ever part throttle, but could notice the pick up was much smoother and responsive. When it was warm, night and day different to the low end. Turns out the S54 is super linear and that dip around 2.5k is gone. I noticed that driveability improved, too. No more oddities with the throttle response at very low speeds like the mild kangaroo hoping with sport button on or the eventual non-existent throttle response for a split second (don't know how to explain, would sometimes happen after rolling into a round about).
All the work done at 98875 miles.
For anyone wanting to know more about this DIY, feel free to contact me. I'm happy to help, and give Z4M specific advice, especially on the timing side. It's two much to write, so it would have to be a call once you're at least familiar with the steps after having read/watched a guide or two.