I then took a detour and decided to try and hunt down the annoying rattle coming somewhere from the passenger door region that had been eating away at me for months. Having taken the door card off I was greeted with this.
Guess that's a quicker way of replacing a window regulator. I've of course had the door cards off before but somehow it hadn't registered. It would have been prior to the engine swap so the priorities would have been elsewhere. I then reached into the door and discovered a handful of glass shards.
Would never have noticed it otherwise but the window was of some random brand and not stamped with a BMW logo like the rest of them. Only then I discovered that it was also the only side window to not have window tints. To top it off it also had a row of little gashes on the inside in one place from something rubbing against it. Not enough to notice on its own, but enough to annoy me having discovered it. I'm planning on redoing the window tints all round before next summer so figured I might as well have a set of original windows and not lock in some random, slightly damaged one. So, being the lunatic that I am, I set off to Pick-A-Part for a replacement original window and vapour barrier.
Having carefully peeled away the vapour barrier and taken out the glass, I discovered that the car I'd been scavenging was pre-wired for heated seats. Score! The seats themselves were already taken, which made access to the wiring that much easier. Naturally I turned a quick half-hour trip for a new window glass into a 5-hour mission of extracting the heated seat wiring all in one piece...
Got to satisfy my curiosity in knowing exactly how it was done from factory and have the full kit ready for when I eventually get around to ripping my interior apart again.
What started off as trying to chase down a rattle had well and truly snowballed out of control. With the window out, I figured why stop there - I might as well remove the door handle and give the whole door a good cut and polish as well. It definitely needed it.
From there on, the window regulator also came out, as did the whole door lock mechanism and everything else along with it until all that remained was the wiring.
"But hey, since you've got it all apart, why not install some sound deadening", said my stupid brain.
The door panel got the same treatment as the hood, minus the wet sanding. Came out pretty sweet.
The door cavity got a proper cleanout with a vacuum and blown out with compressed air. The door lock mechanism, door handle and window regulator got cleaned and lubed up with some white lithium grease. All internals reassembled, I sealed it by taking a heat gun to the butyl tape attached to the new vapour barrier and sticking it on nice and snug. All the door and window rubbers also got some Gummi Pfledge treatment whilst I was at it.
Not that there was anything noticeably wrong with it prior but the door handle and window regulator now seem to operate slightly smoother, and the door sounds that wee bit less tinny when slamming it shut. Took it for a quick test drive around the block and...
...the damn rattle is still there.
Looks like it might have been the seat belt trim inside the B-pilar all along.
Cars are pain.