Ford Focus 1.8 Petrol Leaking Thermostat Housing

October 11, 2012 Ford  No comments

We have a 2000 year Ford Focus 1.8 petrol which has been a great car over the years and has reliably been through the family a number of times. It had recently started losing a bit of coolant so it was brought round to mine so that we could take a look and work out where it was going, it wasn’t too hard to find the culprit! After a few seconds of opening the bonnet we could see that it was the thermostat housing on the side of the engine that was appearing to let the coolant escape!

Tools/Parts required:

  •     Assortment of pliers for removing pipe clips
  •     10mm socket and handle
  •     T25 Bit (?? for removing the main pipe adapter)

Ford Focus Thermostat Housing

It turns out that there is a common problem with the older thermostat housings, as they are made from plastic they have a tendency over time to break inside and that allows the seal to move around and therefore you end up with the leak, in our case the coolant was leaking from the seal, running along the lower bolt and pooling by the head of the bolt.

Ford Focus Thermostat Leaky Bolt

It isn’t a difficult job to fix and will cost about £40 – £100 in parts depending on where you get the parts from, we got the new housing off eBay for £30 and a thermostat from a local factors for just under £10. In hindsight, it would have probably been a good idea to replace the annoying pipe clips with new stainless jubilee clips but for us that will be a job for another day.

Ok, on to the job.

Firstly you will need to remove the pipe clips with whatever pliers or grips you can get your hands on and then carefully ease the pipes off the fittings. Be careful with the small hose on the top of the thermostat housing as they can break quite easily apparently. You will start losing some fluid at this point, once the pipes are off get them pointing upwards as quickly as you can to make sure you don’t lose too much of the coolant.

Ford Focus Thermostat Pipe Clips

You might find that it will be easier to remote the 3 x 10mm bolts that hold the housing in place to allow you to get to the rear lower pipe.

Once the bolts are out and the pipes have been removed you will be able to manouver the old housing out for inspection.

Ford Focus Broken Thermostat Housing

As you can see from the photo above, part of the retaining plastic for the seal had broken and then the seal itself has also mis-shapen and broken.

Quite a difference to the new unit.


Ford Focus New Thermostat Housing
Whilst the old unit is off the car make sure you clean up the mating face of the head as yours will probably look very similar to ours.

At this point it is time to start putting everything back together.

You will need to install your new thermostat in the new housing and if your new housing didn’t come with one (ours didn’t) then you will need to remove the 3 screws (we think these are Torx T25 but ours were so rusted we had to replace them with some similar screws we had in the garage) holding the main radiator pipe adapter on the front of the unit and move it along with the screws over to the new unit.

Manouver the housing back into place and fasten the pipes back in place whilst it is easy to move the housing round before finally putting the three housing bolts back in place.

Ford Focus New Thermostat Housing Fitted

Once finished, you will need to slowly top up your coolant to make sure that you expell any air bubbles and then after checking for any initial leaks start the car up and let it get to operating temperature to make sure that you aren’t getting any leaks under high temperature.

Once the car has cooled back down again (sometimes its best to leave it overnight) then check your coolant level and top up if required.

Disclaimer: The information contained here is to be followed at your own risk, takes no responsibility for your own personal experiences be smart, be safe and have fun!

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