temperature suddenly drops?

What year is it for a start?
Older Mondys Mk I and II (93 - 00) Zetec engines 1.8 and 2.0 were renowned for problems with the temperature guage senders. They would comonly fail and need replacement.
The sender is located under the thermostat housing and is quite awkward to get to. This housing is where the top radiator hose leads to on the engine block. The sender is underneath and easier to get to if the top hose and thermostat housing cover are removed first. I got to mine with a deep socket set over the top of the sender.
They are dirt cheap from Ford ( less than £15 ), and will 99% of the time be the cause of a malfunctioning temp guage.

Steve J
August 2007