Hi Old Bailey,
I realize this is an old thread and you might have already sorted your issue, but I just stumbled on this thread while sorting a similar problem in my '91 HIF44 Carb'd Mainstream Cooper and thought I'd share some information that I stumbled on.
Also see the other thread here for more "how to identify info" that other posters have contributed.
You wrote (and shared a photo)...
IMG_0660.jpegI’ve this at the radiator which I haven’t figured out what it is yet, anyone any ideas?
I'm thinking (only thinking - not certain) that the plug connector in your photo might be similar to this pigtail
If it is that connector, then according to Minispares, it connects to this 12mm thermostatic switch as the "...sensor for [the electric] fan and ECU fitted in sandwich plate below thermostat on twin point cars...introduced by Rover in Tech buletin 0043 for twin point cars where the fan did not work correctly"
And again, according to Minispares, that switch then screws into this MPI sandwich plate atop the thermostat on the cylinder head - the 12mm hole does point longitudinally straight out from the engine towards a wing-mounted radiator, so with that short a bit of wire, it might just be what I [only] think it is.
It's hard to tell from your photo...but it looks like yours is a RHD, with the wiper motor on the left side of the engine bay when seated in the car looking forward (on the right side when bending over the engine with your shins near the bumper)...
But if you have a radiator there on that #1 cylinder side (as well like MY Mainstream, rather than up front at the grill), maybe you have an older Mini with a newer MPI wiring harness?
You did mention that you were in "...the final stages of my Mainstream restoration..." so did you procure a new wiring harness for your rebuild?
Long story short: MY '91 Mainstream seems to make use of THIS combination of a different thermostatic switch WITH bullet connectors that screws into the FRONT of the sandwich plate, and does NOT screw into the the side like the one I've linked to above. It's in the shop right now, but I'll take photos of the wiring routing when I get it back.
it’s a standard mainstream with no changes during its life so everything is as it was from factory.
Just tested the plug on my carb Cooper which is the same as the one identified by The Old Bailey above. Switched the ignition on then stuck a paper clip into the 2 terminals and lo and behold the electric fan came on. So the strange plug in The Old Baileys photo does indeed operate the aux. fan. Only problem now is finding a reasonably priced M8 threaded fan switch to go into the sandwich plate instead of having to fork out £60-£70 or so on those advertised. Ive searched high and low on the net but none so far have an m8 thread.
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The short answer is I bought the mini spares switch and crimped spade connectors onto the new and my old one. So it now works as it should once it’s MOT’d I’ll connect the wires properly heatshrink etc.
Unfortunately there wasn’t a cheaper solution or a solution that didn’t involve cutting the new wiring.
I hope this helps.
