hi peeps,
i have just bought a 1.6 automatic focus on a 54 plate , it has a zetec se engine and the old model. its only done 33k miles and runs sweet.

i did notice however that the radiator cooling fan seems to be on most of the time although the temp gauge sits bang on the middle (there is no aircon to complicate things)
it doesnt seem to have a fan switch in the radiator so im guessing the rad fan is ecu controlled.
today after about 25 miles at normal speeds, the temp gauge shot straight up into the red , i saw it move and it was pretty quick !
i pulled in and stopped the engine imediatley and expected a cloud of steam, but no, the coolant level was still spot on, but the top hose was very hot although the bottom hose was stone cold.
i cracked open the pressure cap a wee bit and could hear the coolant bubbling into the expansion bottle, left it for 5 mins to cool down , gave the hoses a squeeze and fired it up.

temp was back to normal and stayed that way for the 10 miles home.

but the bottom hose is still cold, top one hot.

am i right in thinking the thermostat is in the housing on the side of the head, under the coil pack ? if so then it sounds like its opening ok cos the top hose is getting hot, sounds to me like the impellor has fallen off the water pump and its not drawing the coolant through the rad (hence the cold bottom hose) ? im thinking it may be a circulation problem and the coolant in the head is getting hot enough to put the fan on but isnt being cooled by the radiator,does this make sense /? anyone come accross any thing similar with this engine ? thanks in advance, garry

ps , every time i come to a halt the engine cooling fan is on, but if i switch of the ignition, then back on , the fan stays off.

 

You are correct in what you are saying, the fan control input is from the NTC (CTS) sensor, which is located in the cylinder head, this controls other things, i.e. the temp gauge as well as being a vital input to the ECU for fueling calculations.

Your suspicion about the pump sounds right, they use plastic impellers and are known to break!

Martin

 

im guessing checking/changing the waterpump is a timing belt off job ?
i know the timing belt is a pain in the arse job, so want to avoid it if possible

 

sorted,
the thermostat is in the bottom hose, under the alternator, not the top one .its in a plastic housing that fits onto the back of the waterpump housing. 4 8mm bolts easy to get at once you remove the alternator.
i took the thermostat out and put it in a mug of boiling water and it did bugger all. so put a new one in (Ł7 from dingbro) the temp gauge sits in the same place (half way) but now both hoses get hot (so the coolant is circulating through the radiator) and the fan isnt on all the time.
i could also feel the waterpump impellor with my finger when the thermostat was out and its still attached and turning ok

i hope thats it

 

i did 30 odd miles last night , no problems, everything working fine , i did notice the heater took slightly longer to warm up than before, and once warm, its hot, but not scorchio like before.
i suppose the coolant was hotter with the dodgy thermostat, and most of the cooling was being done by the heater matrix rather than the radiator.

the car had been lying for about 5 months before i bought it and was only doing one or two thousand miles between MOTs laterley. meaby this contributed to the sticking stat.

so beware ! if your rad fan is on most of the time, get it fixed even if the temp gauge is normal.
eventualy something would have given on mine with a sticking thermostat, and it would have been expensive, and the only symptom was the rad fan on most of the time...............................
(and going into the red once)