I have an 88 model 1.6 XR3i that has all of a sudden started to overheat..
Up until yesterday the temp would usually swing between the 8-o-clock and 9-o-clock position depending on the driving conditions..
The fan kicks in a few degrees above 9-o-clock..
Lats night it started to run constantly between 9-o-clock and 10-o-clock positions.. I checked the coolant level and it looked fine.. I tried running the heater last night to pull out some heat as well and it made no difference..
This morning on a short 30 min round trip it went all the way up to just before the red line..
The cooling fan is pretty much on constantly..
Any ideas what could be causing this?
My only ideas is either the thermostat or water pump but if it were either of these the water in the radiator would be cool since it wouldn't be circulating and so the cooling fan wouldn't kick in or the heater wouldn't put out any hot air..
Sounds like the system is air locked (possibly by a leaking head gasket,) check that the air bleed pipe is clear, especially where it goes into the expansion tank. From cold running hold onto pipes and establish whether the thermostat opens or whether hot water gets forced back into the rad via the bottom hose.
Thermostats tend to keep the temperature fairly stable and wouldn't usually be noticeable on the gauge unless you're loading the engine quite a bit (e.g. towing) or the thermostat is sticking.
Sounds about right.
Was the heater blowing out hot or cold air when set to hottest? If it's cold then you've probably got an air-lock.
Well at least you know the fan and sensor are working!
Ummm.... If it was the thermostat then you're right, the radiator should be cool, *however* the fan thermoswitch may not be in the radiator itself (on Fords of that era it tends to be on the thermostat housing) so it could still run even with a cold radiator. I wouldn't suspect your water pump as the engine wouldn't survive 30 minutes of driving with no forced circulation.
Based on your observations I'd go for the thermostat as it sounds like it been progressively opening less and less (hence the gauge going up more each time), until it eventually restricts the flow of water through the radiator so much that it can't cool effectively. The very fact that you can get hot air out of the heater shows that the thermostat is shutting off the flow to the radiator to warm up the engine - the question is, is it opening again and how much?
Of course, it could be that you have a seriously blocked radiator or too many missing/damaged fins but then, you'd notice damage to the radiator and if it's blocked up so badly, how come the heater matrix hasn't?
For solutions, your cheapest option is to warm the engine up with the expansion tank cap off and gently squeeze the coolant pipes - this should be enough to purge any air out. If it's still overheating then remove the thermostat and see if the problem persists (unlikely); if so then you've probably got a blockage or possibly a blown head-gasket. Thermostats for the CVH engine are about £4-£6 for an OEM one but check the temperature rating stamped on the original 'stat as IIRC the CVH used a slightly higher temperature than other Fords (about 88C instead of 82C)
I changed out the thermostat yesterday and it looks like it solved the problem, the temperature in no pretty much pinned in the middle and stays there..
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