OK, so probably the biggest (or second biggest mod I was planning), but still doable in 2 hours first time.
No such thing as third-time lucky, as the hose retainer had corroded and after struggling to even turn it around for 20 mins, it was apparent one off the twin bands had snapped. This meant as much as I squeezed the release tabs, the snapped ring never opened (released), so I had to angle grind.
But that was the only gremlin, in fact this was the "driest" change I'd done and I think I lost less than cup of coolant in total (main reasons were unscrew the drain plug over the bucket :? , and use the reservoir cap up top to control the flow rate - also, to stop the block dripping on me continuously once "drained" in some sort of water-torture - I simply lightly screwed the drain plug back in whilst I continued lying under the car)
I'm rambling, because basically, the method is here:
http://911uk.com/viewtopic.php?t=83808
and
http://911uk.com/viewtopic.php?t=65932
Only real difference between 997 and 996 was the E10 Torx (rather than hex bolts) and "quick" release hose retaining clip (rather than Jubilee)
Oh, and for the 996 I used an insert only (£80 from Hartech) and gasket from OPC (I think £4.50) now I can get a full housing, gasket and insert by Wahler (but housing actually Porsche part) from
https://www.frazerpart.com/ for £45
The part is the same for any M96/M97 (ie 996.1 3.4 all the way through 997.1 3.8)
Note: the Porsche part number has been removed by Wahler (as no one but Porsche can sell OEM parts). But note the official "triangle P" OEM part stamp :floor:
Photo list:
1.) BorgWarner Box (Wahler)
2.) Housing and 71 deg tstat
3.) Part number redaction (but \P/ stamp)
4.) Gasket
5.) Chock
6.) Raised rear by (the higher the better for air-lock mitigation on re-commissioning) - I drove up onto a sleeper and then jacked for a 55cm lift in total)
7.) ... and front view
8.) WD-40'd hardline and housing bolts (and the recalcitrant hose clip)
9.) Draining (and the drain plug on the socket)
10.) Pink!