I finally got around to fitting the TM2 engine temp alarm I purchased a few seasons ago
As recommended, I attached the sensor to a rearmost rocker cover bolt (passenger side in my case). I fed the long cable under the centre of the engine cover and ran it around the edge of the driver side engine bay opening (just to use up some of it length!), securing it under a continuous strip of PVC insulating tape, with the display mounted low down on the fascia towards the footwell area but in clear view and reachable, to the left of the steering using 4 self tapping screws. It seems to work great and I'm going to enjoy seeing what is going on in the engine bay.
Spurred on by this I decided to overhaul the scavenger over-ride facility I'd installed originally 8 years ago but which had been inoperative for some time. My approach was to fit a fresh supply to the fan, fed by a switched relay. But I'd used 15 amp wiring and fuse and the fuse kept blowing because (I assume) the fan was capable of drawing more than that amperage. So I rewired it using 30amp wire (with a fuse) and got it all going again.
This morning I decided to see what the scavenger fan could do. After stopping a warm engine and nipping in to the shops, I switched on to find the sensor reading 84 degrees. I switched on the fan for the 1 minute journey to my house. My the time I arrived the sensor was reading 74 degrees. Part of that would have been achieved by forward movement of the car and by direct flow of cool air over the surface mounted sensor, but I'm pretty sure the major contribution was from the scavenger fan. Its hard to escape the conclusion that the TM2 and the scavenger over-ride switch between them provide an valuable means of preserving your engine in case (1) the factory fitted sensor fails with age and (2) you find yourself in a situation where lack of forward speed means hot air in the bay is not getting flushed out, the more so if - for example - you are labouring and working the engine hard up a long slow incline, though sitting in a traffic jam on a hot day would be another good example.
I don't know if my approach to fitting an over-ride is the soundest although it seems to be working fine. The more recently used method of a switched by-pass to the scavenger fan sensor seems better, but no-one had discovered that one (in fact I don't think anyone had fitted an over-ride at all!) when I opted to make this mod. to mine.
As long as you are happy with making a non-standard mod to a component that is involved with the ECU (the main warning I was given when I did mine) then I'd strongly recommend an over-ride facility on an old Bongo.
