In the process of changing the thermostat housing i lost the spring retaining clip that secures the crossover pipe at the rear of the motor. It fell somewhere behind the motor and could not be found. I called the Mini parts department and found it is not a stocked item. The pipe is rigidly mounted and does not move enough to come off once the housing is mounted so I finished installing everything. I bled the system, let the car run until warmed up and drove around the block, everything was ok. I found the clip where it fell out about 50 feet from the driveway. Now that I have the clip does anyone have any tips or tricks on how install it other than lots of patience and tiny hands?

Does anyone have an opinion if it is ok to leave the spring clip out?

I just did a thermostat housing replacement this morning....literally just finished. Honestly, you will probably be fine driving around until you can get it put back on....it seems that the tube that the thermostat "plugs" into is rigid as well. As I tightened the bolts on the housing, it seemed to press the two fittings together quite firmly, so I doubt that they will come apart.

That said, MINI put the clip on there for a reason, so I would definitely put it back on when you get a chance. Personally, after seeing how the pieces fit together, I'd be comfortable driving around town without the clip, but if I were taking a long trip or something, I'd probably be a bit nervous.

I'm assuming it's similar on the MC (I have an MCS....turbo boost/intake tubes involved). When you remove the airbox from the top of the intake manifold, you can look straight down and see the junction. I was able to grab the clip with a pair of pliers and just press it in. It presses in more straight down than it does diagonally from the back (if that makes sense). Easy to see it and get to when the box is off....even with big hands. Good luck.