i have a focus 1.8 diesel 2003 and it is overheating. i have changed the thermostat and still no joy.the water is circulating around properly. is there a sensor on the engine that detects the heat so the fans kick in? i have tried to switch the aircon on and the fans dont kick in, what is the problem? the fans come on when the engine is hot but the it stills overheats.

 

How do you know it is over heating? Lights, gage, loss of coolant? Bad gage?

Such a tiny diesel, 1.8 L. Is it a 'stone'? Can't get out of it's own way?
About the size of a boat motor down in a sailboat bilge. Ford probably runs these things hot for emission reasons. Fitted with a turbo? That will make it perform for sure. Also heat up. Waste gate working?

Anyway as they said about my XJ-12C Jaguar, ANY temp is fine as long as you do not loose coolant. Many times I have pegged the gage when sitting in traffic on Edens Expressway in Chicago. It gets so hot under the bonnet a box and cooling fan sits around the battery and the power steering pump is fitted with a radiator. And that's with an iron block and aluminum heads with wet sleeves.

Find out what the Ford coolant temperature should be. Might be 160~180 deg. F.
Check V.W.'s designed diesel coolant temperature too. Probably the same.

Check the temp. See what it is. Put a long stem dial thermometer right into the coolant with the engine running...Pull the rad cap and insert. Watch it for 20 minutes. After it's normal or heading toward hot. Take a reading.
You may not have a problem.

Bare in mind that on the water jacket side it's 160~180 deg. F. but 1/4 inch away on the other side of the jacket it's 2,300 deg. combustion temperature. If the water goes past too fast it will not pick-up much heat. Too slow and it's saturated steam. Sits and boils it becomes super heated steam. With the cap off this won't happen, I was just pulling your leg.


Armed with knowledge you will be able to determine if you are within the designed coolant temperature.

The fan on/off temperature switches can be jumped through to make them turn on and pull air through the rad and fins. Fins clean and tight? Watching your thermometer you may note a difference. Ignition timing in a gas engine makes a temperature difference. Can't say about a diesel's timing.


You say you "the water is circulating around properly". So when you look down the radiator neck you see coolant moving around and the heater core is delivering hot air into the cabin. Pull off a heater hose cold and hold it up as high as you can. Start the engine. Does the coolant dribble out, rush out, gush out, or just barely trickles down your arm? We are looking for flow when cold. Or starting to get warm when the thermostat opens up. Weep hole on the thermostat mounting flange up?


And last. I use a product called Wetter-Water in my 82 year old Ford Model 'A'. The long stem dial thermometer says 15 deg F. cooler with it then without it.

BTW, how well does this diesel run? Injector pump injecting the right amount of fuel?

skip.