Hi, I am new here and need help and advice. I have a 2003 Focus with a petrol Zetec SE 1.6L Engine. I have suffered from overheating since i first owned the car two years ago. It started with the temp gauge needle moving from its usual central 50% position to fully up to the red momentarily then back to normal again. It gradually started to get worse to the point at which at anything over 40 mph or under load on a hill the needle hits the red and gradually gets hotter until the ECU light comes on and the engine goes into limp mode!!!! During this time I have renewed the radiator, renewed the water pump, changed the thermostat, drained and flushed the whole cooling system several times, fitted air bleed nipples to the coolant exit manifold to remove possible air locks. None of this worked and the problem has worsened to the point at which I changed the engine, since every expert i consulted said its head gasket and probably a warped head ( expensive repair). I picked up a second hand engine and swapped it with my old one.. the newer engine runs as sweet as a nut but has the same overheating problem. I have read that this was a recall fault on 2001 models and there is an upgrade kit comprising of a new expansion tank and pipes, a new 73 degree thermostat and a pressure relief pipe to splice into the existing coolant pipes..I have scoured the forums for more info and the web for parts but can find nothing more concrete.  Q1 is this true and would it apply to the 2003 model? Q2 where can I get the upgrade parts? does anyone here know of this problem and can help? See text Below Thanks.. Bill

a few ideas - how much coolant can you get in the system, then is the stat opening, its the pump pumping, and the radiator in good condition with the right air flow

But I think I'd start with measuring the actual temp, not believing the gauge is telling the truth

I agree about not relying on temp gauge. Just because the car thinks the engine is hot is it really?  If it really is hot I would remove the thermostat and see how it behaves then.

On the Focus MK1/MK1.5 with 1.4/1.6 Zetec S(E) engine it is a known problem that the PCM starts showing signs of electronic wear. Capacitors and resistors on the circuit board wear out and loose their characteristics. The PCM detecting overheating of the engine while the engine is not overheating at all is a known symptom.

TSB 05-2001 is only appliacable on Focus MK1/MK1.5 with 1.4/1.6 Zetec S(E) engine that are produced before 09-2000. 

 

You should start investigating whether the engine is actually overheating or not by checking/monitoring the actual engine temperature. If the PCM suffers from worn electronic components both the temperature gauge and reading the temperature with an OBD reader are not reliable. 

If the PCM turns out to show signs of electronic wear which is causing incorrect engine temperature readings the problem can easily solved by installing a simple resistor between the sensor wire from the temperature sensor to the PCM. In most cases a 330 Ohm resistor compensates the wear of the electronic temperature measuring circuit of the PCM. This is an easy and cheap fix that makes replacement of the PCM unnecessary.

Hi.....erm what does PCM stand for?

PCM = Powertrain Control Module. 

It is basically Ford's name for the ECU.