Okay, here goes. I am going to assume you are doing just the thermostat housing.
The horror in this job isn’t the changing of the thermostat as it’s only three bolts and five pipes, but making space to get at it is key in accessing it that’s we’re all the time goes. I know of people who will say it can be done without removing the battery…….if you have teeny tiny hands made of rubber.
Disconnect the battery.
1, Disconnect the air intake temp sensor (Gently lift tab and slide of - nb the rest of the electrical connections you will have to take apart are the same type as this so note how it works)
2, Remove the crank pressure relief pipe, spring type jubilee clip at the sensor, gentle wiggle at rocker cover.
3, Remove the air box to turbo pipe, there is a small pipe under this connect to it, it has squeeze clips where it plugs to this pipe, squeeze and push back slightly, then as you withdraw the main pipe it will slide back, exposing a supporting clip that the smaller pipe should be popped out of.
4, Remove the resonator box cover, push clip on top.
5, Remove the resonator box, undo the jubilee clip (7mm) and push the concertina end of the air box, down the rhs of the res box there is a push in clip that allows the box to be withdrawn straight up.
6, Raise the aux fuse group from the top of the battery, two push tab clips on top left and right, and one down on the front of the battery cover, and gently place on top of the main fuse box (piece of string etc and gently tie back to bonnet strut etc).
7, Remove battery cover (lifts from the front, like a bonnet, then draw forwards).
Remove the battery, terminal at the back is 10mm and then the retaining clamp down the lhs is also 10mm.
I also took the rear section of battery cover out, two 13mm flange nuts and there is a plastic cable clip on the back of it. As well as the metal battery tray, two 13mm thread posts on the base (the rear cover flange nuts were on), three 13mm bolts to the left of the tray to the inner guard and one ‘hidden’ 13mm accessed from behind the wheels arch liner.
8, Remove the top of the air box, three torx screws
9, Remove the pipe that was connected to the resonator completely, gently pull forward whilst twisting left to right and it will pop out.
10, Remove the bottom hose off the radiator and allow coolant to drain into something suitable, taking the expansion cap off once disconnected will allow it to flow out quicker
11, 12, 13 Remove the vacuum lines that are over the engine harness support. 11 removes by squeezing the green tabs on either side and gently pulling up.
12 and 13 are just push on rubber pipes, using a pair of needle nose pliers get behind and push the pipe of, pull on the pipe strains it and can damage it. Tuck the two rubber ones back out of the way.
14, Open the flap on the side of the fuse box (it gives a little bit of slack for the next bit)
15, Unplug the coolant temperature sensor (same tab style as before & Unplug the thermostat control wiring, not in pic, but under where the 15 is written.
16, Raise the engine harness support, there is a push tab clip down the lhs and then it will lift straight up, gently rising it up off the thermostat housing, there should be enough slack to gently position it on top of the high pressure fuel pump.
There is a support bracket directly beneath the thermostat housing with a lower section of loom lay on it and attached with 4/5 cable ties. The bracket is affixed to the gearbox with one 13mm flanged bolt to the right and one 13mm flange nut to it left (it’s tucked under, so is by feel to find) 3/8 ratchet and short extension gives best fit for these two. With the bolts undone the bracket can be manipulated forwards to clear the bottom of the thermostat housing.
Standing tow the side of the car looking at the thermostat housing you can now see the five coolant hoses that attach to the thermostat.
The two large pipes going to the radiator are help by jubilee clips, 7mm socket or flat screw drivers will remove these and provide access to the coolant pipe to the turbo. The turbo coolant pipe is easier removed from the thermostat by removing it, as the rubber end section is only aprox 60mm long and doesn’t give much flexibility. Aprox halfway up there is a 10mm bolt attaching it to a support, the banjo bolt on the turbo is a 19mm which is seal on the car by two copper washers (new copper crush washers recommended on refitting or at least a means of annealing them if reusing. The turbo pipe at the thermostat is held by a spring style jubilee clips, remove with suitable pliers or clip clamps.
The two pipes to the right go to the heater matrix, the top one is secured with a standard jubilee clips 7mm or flat screw driver to remove. The lower one is held by a spring style jubilee clip, on a couple of occasions the tang has broken of on this when I have been refitting, so I strongly recommend having a standard jubilee clip 25-35mm to hand for reassembly (Circled in blue below).
I would also suggest at this point to remover the air box bottom. For the lower section there is one torx to the left front corner and then it is mounted on three rubber grommets that by pulling evenly upwards will pop out. With it free, manipulate it the the gap you have created by removing the battery box.
After all that you can see the thermostat housing, but resist unbolting it just yet.
The thermostat housing going into the cross pipe is held in place by a horse shoe shaped spring clip (I tried to find a pic online as I didn’t take any but wasn’t successful) you’ll have to feel along the thermostat housing to where it turns round the back of the engine and feel for where it joins to the cross pipe. The spring clip has a loop out of the top at aprox the 11 o’clock position which you can pull out with your fingers, if you stand to the passenger side wing and sort of crane you neck to the rear of the engine you will just see the top of it as a shiny chrome looking loop. When pulling it out try and keep a pinch on it as it seems to be drawn by magical forces to fall into an abyss if dropped.
CROSS PIPE INFORMATION Need to build a picture first, the cross pipe has a thin lipped groove with an O ring on it where it goes into the water pump location on the other side of the engine. The end we are working receives the O ring end of the thermostat housing. It looks like, from it pictures, like it would be bolted to something along the back of the engine by the three tabs along it, it doesn’t. It is only supported by the O ring on it at the water pump and then the O ring that goes into it, support it from moving when pulling on the housing.
The thermostat housing is held by two 8mm bolts and one 10mm flange nut to the top. Undo all of these and remove them completely. SUPPORT THE CROSS PIPE and start gently but firmly pulling the thermostat housing towards the wing. Resist the want to twist as you pull. The rubber O ring will have sort of bonded itself to the pipe/housing, stick with it and have patience. You’ll see that on my table on the first couple of pictures I was planning on changing all the associated pipes whilst doing the thermostat.
Now you have the old one off, examine the mating face on the block and clean really well, I use a drop of brake/clutch cleaner on a clean rag to make sure the surface is free from any contamination. To ease reassembly I put I very light smear of silicone grease on the thermostat O ring (don’t use oil or mineral grease as it can degrade the rubber O ring).
When inserting the new thermostat support the end of the cross pipe and press it back in to meet the face of the block, also ensuring the O ring of the thermostat is fully home. Reinsert the two 8mm bolts and the 10mm flange nut and bring to just a firm nip.
Insert the spring retain clip, if you keep in mind the 11 o’clock position and feel it back into place it will slide down quite easy, then go round to the wing of the car and jook for a look.
Torque the three fixing on the housing to 10Nm.
Re-attach all the hoses and secure the jubilee clips, the 19mm banjo bolt on the turbo, with the new crush washers, is torqued to 28nm.
Fill the cooling circuit with coolant (I use Coma G30, about 4.5 litres required).
Bleed the system (cold, not running), at this point. There are two bleed points, one on top of the housing and the other is on the upper heater matrix pipe where it meets the bulkhead, looks like a tyre valve dust cap. Bleed the thermostat first, using either a long flat of pozi screw driver until you see a trickle come out. Then back the dust cap off a little agin until you get a trickle. Rem when you are tightening these back up they are plastic, so a comfortable nip is all that’s required.
Go for a coffee /tea/whiskey and when you come back look for any leaks.
Reverse all the other steps to reassemble the rest of the car.
Start the car, put the blower fan on and temp to high, and run for about 20min checking between the engine bay for leaks the temperature guage and the hot air blower. If your getting hot air, moving to a steady 90 degree on the dash with no leaks in the engine bay your probably all good, run it on up for a bit longer and let any small air bubbles make their way around and out. Let it cool, top up the expansion. After your first actual drive of the car, when it cools, you may needs to top off again. If your anything like me i checked before each journey for a few days.
