Unlatch the grey wiring connector from the battery tray;

15 by Chris, on Flickr

Disconnect the MAP sensor. Start by prying out the yellow locking tab then squeeze the black tab to release it;

16 by Chris, on Flickr

17 by Chris, on Flickr

Then unlatch the lambda sensor connector from it’s bracket - You don’t need to disconnect the connector.

18 by Chris, on Flickr

Move the wiring harness (green) out of the way. Next up is the High Pressure (HP) intake pipe which feeds into the throttle body (red).

20 by Chris, on Flickr

20a by Chris, on Flickr

There’s a couple of pipes in a clip attached to the pipe (red) unlatch the clip and move them aside.

The pipe itself is bolted to the throttle body with 2 number bolts which are arrowed in green – The lower of the two being under the pipe. They’re 5mm allen bolts.

21 by Chris, on Flickr

The bottom end of the HP pipe is bolted to a bracket using another 5mm allen bolt, undo this as well;

22 by Chris, on Flickr

The lower end of the pipe is married to a flexible pipe. Access to the clip holding them together is limited. You might be able to get at it to undo it from underneath, which means jacking the car up and faffing with the undertray, if fitted.

But, as the pipe is flexible, you DON’T need to undo it. You can simply wriggle to the other (top) end free of the throttle body and pull the pipe out of the way to access the thermostat;

23 by Chris, on Flickr

And there it is. The thermostat….

23 by Chris, on Flickr

24 by Chris, on Flickr

27 by Chris, on Flickr

It has 5 number coolant connections (circled in various colours below and an electrical connection to the temp sender. Interestingly, my new thermostat cam with a new temp sender already fitted – circled green. This is released in the same way as the MAP sensor.

Now you need to think about where the coolant is going to go. Downwards usually. If you have an undertray fitted, you should jack the car up and remove it, otherwise the coolant will soak into the sound insulation.

Based on what I’ve read recently, most owners have elected to remove the undertray on the assumption it prevents the subframe from corroding.

Either way, I’ve not considered removal as part of this thread as mine doesn’t have one fitted.

Coolant is nasty stuff, it’s sticky, it migrates easily and it’s poisonous. Don’t let your pets anywhere near it.

 

Moving on…

The smaller pipes circled orange and blue are held in place with standard clic-r clamps. You can release them with a small pic or flat blade screwdriver.

The big pipe circled cyan (light blue) feeds the radiator. In my experience they come with a clamp that can’t be reused from the factory. This needs to be cut off. Use a pair of side snips to cut the “belt buckle” off to remove it. You’ll need to replace it with a jubilee hose clamp. In my case this had already been done. The clamps have various diameter drive heads that usually include a cross head for a screw driver, but you’re better off tightening it with the hex head – either 6, 7 or 8mm depending on make.

26 by Chris, on Flickr

The remaining 2 hoses feed the heater matrix in the cabin. They have “quick” (yeah right, not after 213k miles they’re not!) release connections…

“Simply” prise up the spring clips (you don’t need to remove it, just lift it up) and pull the hoses away;

28 by Chris, on Flickr

29 by Chris, on Flickr

That’s it. All that’s left is the 2 13mm bolts holding the thermostat to the side of the cylinder head. Un do them and lift it out. The bolt locations are circled in green below;

30 by Chris, on Flickr

New and old thermostats side by side;

31 by Chris, on Flickr

Note, the ‘o’ ring pictured is from the old one. The replacement ‘stat should come with a new one already fitted.

Before fitting the new part, make sure the face of the head where it fits is clean of debris and corrosion. I cleaned with a solvent (white spirit) and a wall paper scraper.

When fitting the new thermostat, remember the bolts are going into an alloy casting, so they don’t need to be particularly tight. The ‘o’ ring is doing the job of sealing it.

Refit everything in the reverse order.

Curse about having to reset the time date and personal preferences.

Top up the coolant using a suitable coolant type – make sure it’s the right stuff - Usually red longlife coolant and of the right concentration which is dictated by the manufacturer. 50/50 with water usually.

Run the engine up to temperature with the cap off, tighten it once at 90 deg and keep the engine running until the fans kick in (make sure that the air con is off…). Check the coolant level regularly for the next week or so, topping up as necessary.

- Note - I couldn’t find a bleed screw on the system and AFAIK, there isn’t a readily available workshop manual to confirm this.

Consequently, this guide is based solely on my own experience and I take no responsibility for any ensuing carnage!

Good luck.

 

Consequently, this guide is based solely on my own experience and I take no responsibility for any ensuing carnage!

I have created carnage, and hold thee solely responsible! Jk jk... but yeah those 'quick release' connectors are an absolute pig. I've managed to snap one barb off the thermostat which is now stuck in the connector, and the second is refusing to budge and I'd rather not repeat my mistake. Using silicone grease on sealing surfaces for reassembly would probably be a good idea!

 

Thank you for this, I've got this job to do next week, Managed to get w thermostat at an eye watering price of £90 (thanks brexit) and fully expect this to take 15 days, 4 knuckles, a £300 investment in extra tools and a new engine if past work on this car is anything to go by. Wish me luck.