fitted a 1.6 cvh engine in my mk3 escort new stat fan switch temp sender etc but fan cuts in right in the red and only for about 5 seconds is it possible i have a defective fan switch i thought the fan normally cuts in around 3/4 on gauge and stays on for atleast longer than 5 seconds . heaters blow hot so dont think its airlocked coolant level not dropping tried with stat out still same but takes longer to get hotter top and bottom hoses hot

 

I have always been told that the fan trigger switch either works or it doesnt so i would say everything is fine and it could just be you have the wrong temp sender or your gauage is out. The one on my turbo only came in just as it was touching the red, its just the way it was.

 

but why the fan only operating for approx 4 to 5 secs

 

The ultimate test is leave it ticking over for ages till the fan has cut in and out a few times, if it doesn't overheat don't worry.
I would as you thought assume the fan would come on for a minute or two, but if it's doing the job then don't worry.
I would say your guage is out, same as my car, my fan cuts in at 95C, then off at 92C, this can be anywhere on the gauge from the "M" to the "R", so I know I have a dodgy gauge!!
tabetha

 

problem solved new fan switch was duff got another new one kick in just before red stays on for about a min droppin it down between half and three quarters