I have a mk5 escort converted to rst power (s2).

The problem i have is that the fan isnt comming on, and the temp guage inside the car is sitting in the block below normal for ages when its left ideling (bout 30 minuites) thing is the engines getting really hot and its started to bubble.
I shorted the fan out to test it and from cold the temp guage is doing the same thing, but the waters fine in the pipes. No sign of oil in the water, the pipes arnt too hot (you can touch them fine) theres no air bubbles or pressure in the pipes either. i turn it off so the fans off and it bubbles with pressure in the pipes, but strangley not when its running. the pipes also get hot but im thinking thats down to haveing no circulation.
I expect theres a faulty sender and its thinking its colder than it really is so it may be sticking abit. as if i put the ignition/fan back on it cools down fine.
is the fan sposed to stay on when youve took the keys out of the ignition, as mine one isnt?

ive flushed the system incase of a block and it was fine.

its also giving out lots of heat from the heaters, so tjere shouldnt be a air block in the system?

does anyone else have any ideas as to what it could be?

 

Thermostat opening?
take it the fan goes on when shorted out but not when pluged in as normal? (replace fan switch)
earth the plug for the temp guage sender...does it now go right up to the top on the guage? if so, replace temp guage sender. their only a few bucks, as is fan switch.
header tank cap in good nick? not leaking?
Fan should stay on with ignition, not when keys are out.