After a spot of advice.
A few weeks ago I decided to swap my cooling system over to a header tank style, having got a little tired of loosing a bit of coolant into the expansion bottle of hot days.
I got a Fiesta/Escort thermostat housing (rather than just run a blanking cap as I was keen to increase the bonnet clearance) and an expansion bottle (http://tinyurl.com/m6vc4n8
). I run the Raceline water rail and was running a heater bypass pipe (connecting the submarine pipe to halfway along the water rail) so I plugged the water rail connection and took the pipe from the submarine pipe and connected it to the heater tank, which I mounted as high as I could where the heater used to be. I also took a small pipe from the T'housing to the heater tank for the air to escape.
The other evening, when driving home from the pub meet, I noticed that the temperature was cycling - it would increase to around 100 deg before dropping rapidly. It would then repeat this, mostly stabilizing by the time I arrived home.
Now, I've never had this with the Raceline waterrail, but I do know it was a bit of an issue - the temp would build until the thermostat would open, letting cold water circulate, closing the thermostat, and so on.
So, I decided to try adding the bypass pipe back onto the waterrail, connecting it into a T-piece in the submarine to header pipe. This, however, has not worked as now the water is being pumped up through the engine and out of the waterrail pipe into the header tank, the air being expelled down the small pipe to the T'housing. The header tank fills up to the top and eventually leaks, but if I switch off, the water level drains back immediately and likewise, if I pinch the small pipe, the header tank doesn't fill up until released.
So - for the time being I have reverted to a non-header tank system to keep the car on the road while I figure it out.
What have I done? Anyone running a Raceline waterrail and a header tank - if so, what is the plumbing setup? I feel I need the bypass bit to keep water flowing around the engine, but it is causing the water level issue. The thermostat I have is an 88 deg one which has its own built-in small bypass hole, but I haven't, yet, drilled any additional holes.