Originally Posted by
sideways_madness
another thing i just fitted an alloy rad and i was wondering is there any way of testing my fan switch? as i dont know if it is uprated or standard? i see MSD also sells a UPRATED Ford Sierra Cosworth Fan Switch. (Sensor)
but MSD done nearly oll the work to my car going by all the recipts so they may have suggested/fitted one of these already?
The standard switch is red, where as the "Uprated" one is typically green or white, in any case the switch has the span written on it, in the case of 2WD the switch closes at 86 degrees.
The trouble with the standard one is in that it has a huge span and brings the fans on too early and keeps them on for to long, the latter is what causes the melting of the fuse etc.
If you have an alloy rad you need the "Uprated" one really as the standard one suffers from a heat soak effect and you may find the fans stay on indefinitely.
To test you simply need to remove the connector from the switch and bridge the connections, which should start the fans. The switch isn't usually the problem, as said the fans need rewiring along with the fuel pump wiring.
As said re your initial post, the cause will be the ignition system.
Martin