So about 4 weeks ago my car started overheating on the motorway at about 70mph, I changed the thermostat and it still overheated the next day but then the next it wasn't, a couple of days later I noticed coolant leaking from the water pump and it was making a grinding noise but still not overheating, got the water pump and timing belt done about 2 weeks ago the cars running smooth and a lot quieter ( no grinding noise ) but started overheating again, since then I've changed the expansion tank cap ( only from scrap yard not brand new ) flushed the system with Holts 2 part rad flush tested for head gasket leak with block tester twice both negative. It's driving me mad!! All ideas and input welcome. It's a 2000 1.6 Zetec 99k, oh and heaters in car work fine as in blow hot and cold although do smell abit funny now and again not sure if related, I've read somewhere about a PCM update?? Also cooling fans kick in at 104 degrees C?? I think that's abit high but hopefully someone can shed some light on the situation

U sure it overheating an not fault coolant temp sensor

Cheers for the reply, that was gonna be my next step just wondered if anyone else had experienced similar issues

Right u replace thermostat an water pump hot air in car done sniff test in engine not head gasket so check rad not blocked an every hose on car gettin hot if no blockage has be sensor

Sorry I read that wrong I was gonna change the cylinder head temp sensor not coolant temp sensor?? Or am I being dumb and there the same thing??

Yeah they basically same thing it has one or other cylinder one measures temp of the metal an coolant measures the coolant Urs is cylinder I think not coolant I just call them all coolant temp sensor but ur right

Ok well I'll change the sensor and let u know the outcome in the next few days, cheers again for the reply

U can test wit a multimeter but not that expensive for sensor keep us posted with outcome

Not done the sensor yet, but noticed that when I finished driving sometimes the bottom rad hose is hot and sometimes it's cold is this normal??

Sounds like a potential blockage causing the coolant not to circulate efficiently.

I flushed the system a few days ago so would of thought that would clear a blockage? How could I determine where the blockage could be? ie radiator, hoses etc

Also after driving and the car overheating (according to temp gauge) after switching car off and waiting for the fans to stop of course I've actually put my hand on the radiator through the gaps of the fans and the radiator is stone cold?? Surely if the car is apparently overheating the rad should be hot shouldn't it??

Wat u flush it wit only water be no use bud

you need to get the engine hot, then move your hand around the hoses and find it. There will be a point where it starts to cool down!

I flushed it with Holts 2 part rad flush

I flushed it with Holts 2 part rad flush, should the rad be hot or cold if the cars apparently overheating?

rad should always be hot, or at least very warm!

So do you thinks it's cold because a blockage is stoping the coolant getting there or the rads shot?

Ok now this may sound mad but this is wat I have done before go to a plumbing shop an buy domestic flush which is suitable for rubber seals an run this for an hour or two then complete flush with thermostat out this worked for me an didn't burn any seals I kid u not

the rad will not always be warm in this temperature the rad will likely not be used as if it did open in the temps now as youre moving it would close quickly to prevent over cooling the coolant will bypass the rad as its meant to circulate through the head and back to the expansion tank this will continue till the temp gets hot enough to open the thermostat then it will go through the radiator leave the car running at idle it will take a while though with the dash test on when it shows 140 head temp leave it to keep idling you should hear the cooling fan kick in now check the rad and bottom hose do the job right mate you may just find youre rads fine if you do the above and its still cold then the thermostat is likely stuck closed

It does seem as tho the thermostats not opening but that was the first thing I changed?? I suppose it could of been a duff but I didn't bother checking it before fitting it as it was brand new out the box and people are telling me the thermostat must be working or else I wouldn't be getting heat from fans inside the car, is this true?

Where did u place the giggle pin on stat top or bottom

At the top, I put the new one in exactly how the old one was

No that's grand just least we ruled that out so did u leave it idle for while an check hoses again

No I just finished work but as soon as I got back after the temp gauge jumping up and down the whole way back and fans going mad checked the hoses and the top hose was hot and the bottom hose and rad was cold