exposing vacuum lines behind M54, to find a mystery leak

[workingonit]

Ok, the weather is about to get cooler around here in N.Texas, and the X5 and my other cars/trucks have either passed inspection (X5, GMC, Lexus, Chevy 2500HD) or will, later this month (HHR Panel... it tests OK per my Foxwell). Side note: It gets sorta expensive, all my vehicles needing inspections and registration renewals in Sept., Oct., or Nov., especially if I need to do repairs to make them pass.

Now's the time for my annual (or more frequently done) "search for the mystery vacuum leak" on my X5. The fuel trims are always on the lean side, and I'm regularly cleaning and/or resetting the MAF sensor, to prevent P0171 and P0174 from setting a CEL. Long term trims are always above zero, and slowly climb (unless I'm on a super-rare, extended...20+ mile, highway run).

This year, I'll delve deeper into the bowels of my engine bay, by taking apart the plastic microfilter housing and associated crap covering the rear of the engine, since I can actually park the X5 in a garage bay (recently cleared-out for my wife to park her "new" Lexus in), out of the open space where my vehicles live outside.


That space is dirty (sand, gravel, Oak tree leaves and debris blowing around) and open to invasive critters (we have mice, squirrels, 17? feral cats, free-range chickens from the neighbor's yard, and snakes and insects of all kinds); if I open up anything automotive outside to work on it, it's most likely to have something unwanted getting or crawling inside. The three garage bays (two are semi-permanently taken over by non-vehicular items) have much less likelihood for similar contamination, so I'm moving the X5 inside for a short-term exam.

I'm either rebuilding my home-made smoke tester (it needs greater output) or I'll buy a cheap one from Amazon or Ebay (not wanting to, having just spent about 2 grand on parts, repairs, tires, inspections, and registration renewals in a just over a month, from Sept.29-Oct.31), and try smoking out the mystery leak (my twelfth attempt, IIRC). This time, with no wind or bright outdoor light making the smoke disappear.

So, here's my question: when I remove all the obstructing covers over the rear of the engine, can I expect any difficulty upon reassembly, or possible breakage of 22+ year-old plastic pieces? I'll also be using an OTG/phone borescope, mirror, and stethoscope (I might hear an invisible leak?).