Thermostat replacement

Mark 3 Ford Mondeo Thermostat Change (1.8 or 2.0L Petrol Duratec HE)

Symptom: car takes more than a few minutes to produce hot air on a cold winter's day, and even then, it's not as hot as it should be. You can also use the cluster diagnosis tools to view your cylinder head temperature, which should reach 90-105°C after a few minutes driving, then stay there.

Thermostats always fail in the open position. In the old days it cost 5 quid and took 5 minutes to change. On the Mk3 it has fancy electronics, costs 90 quid and the garage will quote you at least 60 quid to fit it. It's in a terrible location behind the power steering pump.

Fuel economy was also bad as car was constantly revving at 1,200rpm as it though engine was cold, hense using more fuel.

BTW, to confirm it's a 2001 1.8 Mondeo, job took me about 1 hour.

So I fitted a new thermostat and took some pics to post a little how-to.

I'm not that great with working on engines but this is a pretty simple procedure to do, it's just a very tight place you have to get to which takes the time and skin off your hands. If you can change a set of break pads like myself then I think you will have no problem with this job.

Let's get started - make sure you have all the right parts, these are all the tools I needed -

1 - New Thermostat in housing (£75 from ebay) 2 - plyers 3 - magnetic tool (for those dropped screws...) 4 - small ratched set (only need 10mm/8mm bits) 5 - 4l bottle of engine coolant/antifreeze

You may need a torch too, even in good daylight.

Now out to the car, open up the bonnet and remove the front grill, there are two small plastic clips either end holding it in place, twist these and pop then off, the whole unit will then pop off, just don't force it so you don;t snap any of the small platics holding it in place.

Now pop out the drivers side headlamp, I was suprised how easy this was, in the pic below are two small metal posts, these just pull upwards to release the whole headlight, just unplug the electronic connector at the back and the headlight will wiggle free.

Make sure you unplug the connector before you start pulling the headlight out

Now the headlight is out we have the essential access route to the Thermostat.

Below is the view that should greet you when you peer though the empty headlight socket. First remove the large coolant pipe, I found it best to use plyers on the clip, it realy is horrible and will take a few goes to move but keep at it and it will eventually move, I promise!

And now with the large hose removed...

You will lose quite a bit of coolant when the big pipe is removed. Next undo the 3 nuts that hold the Thermostat in place (Blue lines in pic) these are all quite hard to get to, you will loose skin, blood and possibly a nail. Be careful not to drop the nuts, or the magentic tool may have to some out..... You may find it easier to undo the nut holding the power steering hose bracket, this will give you a bit mote room. When all 3 nuts are out you should be able to move the Thermostat into an easier position to remove the electrical connector and smaller hose.

Now everything is removed you can take out the Thermostat, below is a picture of my faulty one, you can see that one of the plastic arms has snapped off causing it to stay in only one position.

Now you can install your new thermostat ! you should know how to do it now, I would place the small hose on first, then screw in the three bolts (this may take a while as it is so fiddly) then clip on the electrical connector and finnaly spend a while swearing at the large coolant pipe as you try and get the clip back on. If it's too hard you could always put a jubilee clip on.

Nearly done, the thermostat is now fitted but we have lost a fair bit of coolant - this need to be topped up but with engine running and filler cap off as there will be air locks in the system which need time to reach the filler tank. Run the engine for about 10 mins revving to about 2500 rpm and checking the coolant level every min or so, keep doing this until the level remains constant and no longer drops.

Done, you should now have a warm car that knows what temperature it's running at and is not wasting fuel!