Part 1.
My heater circuit is 15mm I/D pipework with shut valve right at the heater matrix. My bypass is a 10mm tube (O/D I think) linking feed and return pipes as picture.
![Image](http://i241.photobucket.com/albums/ff42/richardpope50/By-pass%20-%202_compressed_zps17cdtczd.jpg)
![Image](http://i241.photobucket.com/albums/ff42/richardpope50/By-pass%20-%201_compressed_zpsfsub3ynx.jpg)
Part 2
My setup: Dax Ally rad was just an ali version of the Cortina rad. Cortina rad is thin and tall so in a Rush cannot be vertical and extends below nose cone opening where there is no air flow. My rad is short and thick (75mm 4 core) to match / use all the nose cone’s air flow and be as vertical as possible.
I have a nose cone cowl that directs all air flow through rad. Unlikely for any air to escape.
![Image](http://i241.photobucket.com/albums/ff42/richardpope50/Rad%20cowling_compressed_zpsgkq8oyst.jpg)
I have a puller Kenlow rated at 3,125m3/h. Highest capacity I could find and fits close to rad. I can feel plenty of air flow through my flared side panel when sitting at idle so there is plenty of room for air to escape.
![Image](http://i241.photobucket.com/albums/ff42/richardpope50/Kenlow%20Fan%20-%201_compressed_zpsyvnvt9o5.jpg)
Thermostat is a straight housing (photo) and standard thermostat that opens correctly. Header tank is above all levels except probably heater pipework - cannot be located any higher. I do not use / lose any water from system.
![Image](http://i241.photobucket.com/albums/ff42/richardpope50/Overall%20Water%20Flow%20layout_compressed_zps1rjbkfzr.jpg)
![Image](http://i241.photobucket.com/albums/ff42/richardpope50/Thermostat%20Housing%20amp%20Heater%20feed_compressed_zps6vx1bv2j.jpg)
Fan speed 1 controlled by ECU sensor near thermostat housing – brown sensor in photo. Speed 2 controlled by inline sensor in rad input pipe – see photo. Same place as header tank pipe connection. Fan stage 1 = on 92, off 87, stage 2 = on 95, off 87. I consider normal to be 90 and too hot 105 / 110 being the temp I seem to be running at.
Part 3
Tom’s right, my belt only covers about a quarter of the pump pulley however there does not seem any sign of a shiny belt. That said, I found an old idler bracket I had made some time ago together with a sprung pulley wheel so I fitted it this week making a true ‘W’ arrangement. Went out yesterday and it does seem to hold the temp at 105 max and my fan comes on / off much more than it did meaning it heats up then cools down. On the 25 mile trip I also got the temp down often to < 95 so perhaps that was it. Still a bit too hot but will now try the 10/40 oil.
Part 4.
Got back and parked in driveway. Now I do not have any 12v ignition circuit! Never ends.