Apologies for the lack of photos - I didn't think about this being useful until "after" the event and I'm trying to avoid taking everything apart again.
The Problem
The M22 x 1.5 threads on the RHS of the oil cooler are mashed up by the mild steel oil pipe fitting.
The Solution
I found that there is still some good threads left on the oil cooler beyond where the steel fitting screwed (perhaps 5 turns) - this gives us something to work with.
Step 1 - Buy these.
1x M22 x 1.5 Female Socket : http://www.ebay.co.uk/itm/301178655701 2x M22 to AN10 adaptor (The shorter Setrab one as per here - there is a longer type also) : https://www.ebay.co.uk/itm/382268993413 2x AN10 45 Degree Fitting : http://www.ebay.co.uk/itm/150781418512 1 metre AN10 : Stainless Steel Hose : http://www.ebay.co.uk/itm/360881217559 AN-10 Separator : http://www.ebay.co.uk/itm/360929317656
(FWIW - I've bought loads of fittings from Torques UK - the quality is great, the range is excellent and their service pretty damn good too. I recommend them)
Step 2 - Clean up the remaining threads on the oil cooler and make sure they're not full of swarf/oxidisation and fully degreased. Stuff a blue Shop towel (not rag) down the open end to make sure you don't get any swarf etc in the end.
Screw on the M22 Female socket. It will need some adhesive - you could perhaps use thread lock, but I I decided I want this socket to be a permanent fitting on the cooler and I've found JB weld to be the best consumer epoxy I can lay my hands on.
Step 3 - Unscrew the oil filter end of the existing hose and the adaptor - you will need to remove the OS intercooler hose.
Step 4 - Screw in the new M22-AN10 adaptor into the oil filter housing. Make sure you include the o-ring - or possibly you may want to replace it with a 22mm copper washer and a littler sealer.
Step 5 - Make up one end of the hose with a 45 degreee AN-10 fitting on. There's loads of guides how to do this well, so I won't cover it here. Make sure the internals of the hose are really clean. (FWIW, for cutting hose I recommend binding the hose with electrical insulating tape and cut it in the middle of the tape with an angle grinder with a 0.8mm cutting disk).
Step 6 - Temporarily route the hose through and hand tighten on the oil filter end. Measure up the length of the finished hose to the oil cooler using the 2nd 45 degree fitting. It is approx 0.7m IIRC.
Step 7 - Make up the finished final hose end. As above - make sure it's super clean internally.
Step 8 - Final install it and use the separator to mount it tidily. The new An-10 hose is a little large than the old hose, so it is a little tight - but it's fine.
Step 9 - Have a beer and congratulate yourself for saving several hundred £££ on the cost of a new oil cooler and various hoses (Because you know you'd have to replace a bunch of other hoses too when replacing the oil cooler!)
Final thoughts:
- I used the standard AN-10 Oil and cooler hose just because I have some stock from other projects. It fits well, but is a little tight @ 20mm diameter. If you use teflon hose, it's 16mm diameter so might give a little more room to maneouver. Check which fittings you'd need if you go down this route - they may be a little different too.
- In the oil system, cleanliness is paramount. Before hooking up either end of the hose, be really careful to make sure the hose is super clean. Just because this hose is before the oil filter is no excuse - oil filters have a bypass valve in them, so not all the oil goes through the filter, especially when cold!