Bob,
There are a number of things that could cause a high temperature reading -
check each until you have a solution:
Dodgy voltage stabiliser - this is a little box, that should be hanging off the
back of your speedometer. Its job is to take the rather variable 11-14 volts
from the battery, and give a stable 10V for the guages to work off. If it has
decided to die (as they sometimes do for no good reason), it will give the
full 11-14V from the battery. Test is simple - does your fuel gauge still
read correctly? If this too is high, it is your stabiliser, and it needs
replacing.
Temp gauge sensor - could just have got wet, in which case it will be fine once
dry. The water will provide an alternative source to ground for the
electrical current - the gauge works by sensing the resistance to ground of
the sensor, which is grounded in its housing, and its resistance varies with
water temp. It could be totally mis-functional, but in that case I would
expect you to get no reading at all.
That's it for the dodgy reading section. Now for the genuine overheating
section -
Is there enough coolant? You've checked this, the answer is yes, so it's not
that.
Is it a hot day? This will be enough to cause a Spit to overheat, particularly
in stop-start traffic, or if driving hard.
Is your fan belt tight enough? If it is even slightly loose, it will turn the
pump a bit, so some coolant will circulate, but not enough.
Is your thermostat operating correctly? Take it out, and stick it in a pan of
water, with a thermometer. Slowly heat the water, and check at what
temperature the thermostat opens. I think it should be about 180-190, but my
memory could be wrong, so someone out there please correct me.
There are no doubt other problems people can add, but I think these are the
most likely.
Getting the ignition system wet is unlikely to cause over-heating - if it does
anything at all, it will prevent the engine running completely.
It could be your timing - early timing will increase engine temperature. Worth
checking, but if the problem came on suddenly this is a less likely cause, as
timing is more likely to go off gradually over time.
Hope this all helps,
Richard & Daffy
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