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Great thread, thanks!

After being quoted north of NZ$300 for the job (GBP150), I decided to do it myself.

The local Alfa dealer parts here are just a ridiculous price - $180+GST (GBP 105) for the thermo, plus 'special' coolant and it became apparent that it was going to be a DIY job.

I sourced an OEM thermostat from Poland for 29 quid, shipped, which arrived in about 8 days! Congratulations Poland Post - the fastest I have had from Europe.

Now to dirty up my daughter's drive.
 

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This is by no means the definitive guide to changing a thermostat but is how I did it (with inspiration from Andymac). Its meant as a rough guide and I take no responsibility for you damaging your own car whilst using this info.

Click on pictures to enlarge.

You will need a new thermostat, thermostat gasket (mine came with the stat), 1x 29-41mm hose clip, 1x 10-13mm hose clip and 2x 13-19mm hose clips as well as an assortment of tools.

1. Open bonnet and remove air intake pipe that goes from the airbox to the throttle with 7mm hex socket.
View attachment 39305

CAUTION: do not turn the ignition on with the temp sender disconnected.

2.Remove big hose at the front of the thermostat (lots of coolant will come out), the small hose at the top, the hidden hose underneath at the front and disconnect the temp sender(the bit with the wires at the top). Note there is still one hose connected at the back. Unless you have the special pliers that takes the clips off you may have to cut them.
View attachment 39306

3.Using a 13mm socket remove the two bolts that hold the thermostat onto the side of the engine. Prise the thermostat away from the engine with you hands and disconnect the last hose on the back.
View attachment 39307

4. Take time to clean the mating surface of the engine being careful not to scratch it or get debris into the engine. Wash the drained coolant out of the engine bay as well.
View attachment 39308

5.Using an appropriate spanner, transfer the temp sender to the new thermostat giving it a good clean with solvent as well. You can buy new ones for about £15 but I am too mean.
For added support you can remove the temp sender wile the thermostat is still attached to the engine.
View attachment 39309

6.Refit in reverse order using the two 13-19mm clips on the lower hoses, one 10-13mm clip on the top hose and the big 29-41mm clip on the front hose.
View attachment 39310

7.Refill the coolant (50% mix) upto the max line and squeeze several times on some of the big hoses to bleed slightly. Then refil back to max and replace cap.

8. Re-install air intake pipework.

9. Start the engine and look closely for any leaks. Let the engine run up to normal temp while keeping an eye on the coolant level and for leaks.

10. let cool down for a couple of hours and refill the coolant to max, as the system will have bled itself.

11. The next few times you use the car check the coolant level before you start and top up if neccesary. Make sure to check the coolant level with the cap removed.

12. Enjoy :thumbs:

If you are an AO member please leave feedback on the topic of 'how to do guides' @http://www.alfaowner.com/Forum/club-requests-and-ideas/100017-how-2-guides.html
Thank you
 

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Hi I'm new to Alfa and this site,I recently bought a Alfa 156 and I find driving normally the temp sits at about 65 degrees c and when I stop awhile it goes up over 95,I don't hear the fan kick in and I assume my thermostat is stuck open,my question is and forgive my asking as I haven't stripped it yet but why do we have to replace the whole body,dont Alfa make a replacement thermostat without replacing the whole body
 

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The thermostat and housings are all one piece, you cannot seperate them so you need to change the whole lot.

It is a right PITA especially as they fail so often.
 

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This is by no means the definitive guide to changing a thermostat but is how I did it (with inspiration from Andymac). Its meant as a rough guide and I take no responsibility for you damaging your own car whilst using this info.

Click on pictures to enlarge.

You will need a new thermostat, thermostat gasket (mine came with the stat), 1x 29-41mm hose clip, 1x 10-13mm hose clip and 2x 13-19mm hose clips as well as an assortment of tools.

1. Open bonnet and remove air intake pipe that goes from the airbox to the throttle with 7mm hex socket.
View attachment 39305

CAUTION: do not turn the ignition on with the temp sender disconnected.

2.Remove big hose at the front of the thermostat (lots of coolant will come out), the small hose at the top, the hidden hose underneath at the front and disconnect the temp sender(the bit with the wires at the top). Note there is still one hose connected at the back. Unless you have the special pliers that takes the clips off you may have to cut them.
View attachment 39306

3.Using a 13mm socket remove the two bolts that hold the thermostat onto the side of the engine. Prise the thermostat away from the engine with you hands and disconnect the last hose on the back.
View attachment 39307

4. Take time to clean the mating surface of the engine being careful not to scratch it or get debris into the engine. Wash the drained coolant out of the engine bay as well.
View attachment 39308

5.Using an appropriate spanner, transfer the temp sender to the new thermostat giving it a good clean with solvent as well. You can buy new ones for about £15 but I am too mean.
For added support you can remove the temp sender wile the thermostat is still attached to the engine.
View attachment 39309

6.Refit in reverse order using the two 13-19mm clips on the lower hoses, one 10-13mm clip on the top hose and the big 29-41mm clip on the front hose.
View attachment 39310

7.Refill the coolant (50% mix) upto the max line and squeeze several times on some of the big hoses to bleed slightly. Then refil back to max and replace cap.

8. Re-install air intake pipework.

9. Start the engine and look closely for any leaks. Let the engine run up to normal temp while keeping an eye on the coolant level and for leaks.

10. let cool down for a couple of hours and refill the coolant to max, as the system will have bled itself.

11. The next few times you use the car check the coolant level before you start and top up if neccesary. Make sure to check the coolant level with the cap removed.

12. Enjoy :thumbs:

If you are an AO member please leave feedback on the topic of 'how to do guides' @http://www.alfaowner.com/Forum/club-requests-and-ideas/100017-how-2-guides.html
Thank you vwry much
 

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I think most of the ones I have fitted were made by Facet.

Had no problems with them...

My last two have been Facet's ... the new one was put on when I had overheating problems .. turns out it wasn't the thermostat ... but a hole in the head-gasket! :censored:

Anyway that's now fixed and just need to swap out the radiator rheostat to get low speed fan working again .. that's on the bench waiting for a day when my hands won't freeze to the the spanners! :biglaugh:
 

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I have replaced twinspark thermostats before, but I have read through this as a reminder as my 156 1.8ts thermostat must be stuck wide open, the temp never gets of the low mark until I stop. Doing it this weekend, this was well worth a read through. Many thanks.
 

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I'll blame spellcheck! :)

I've had my fill of thermal fuses on the MiTo heater ... THREE resistors died in weeks .. have replaced one and that's been working fine no for a couple of months. Slightly dirty pollen filter (but not clogged), one small leaf in fan but rust forming near the bottom motor bearing .. may have been causing the fan to overload.
 

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I'm about to do this on my own, very novice but it seems manageable.

Question is, I don't have a new gasket, only a new O-ring in the package that the thermostat came with. Do I really have to have a gasket or can I use any liquid gasket or some kind?

Thanks!

Update. In the picture I've marked a hose with red. What's that? On MPH's pictures that one is not there. Is it safe to disconnect?
 

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I'm about to do this on my own, very novice but it seems manageable.

Question is, I don't have a new gasket, only a new O-ring in the package that the thermostat came with. Do I really have to have a gasket or can I use any liquid gasket or some kind?

Thanks!

Update. In the picture I've marked a hose with red. What's that? On MPH's pictures that one is not there. Is it safe to disconnect?

No gasket and no sealant required. Just clean the face to the engine with some fine wet&dry paper. The o-ring will work fine.

That's the throttle cable .. leave that well alone!
 

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Have just read through the guide and have a couple of questions about filling the coolant back up after changing the thermostat...

When starting the engine should you set the heaters to hot and have the blowers on full?

Also, should you remove the coolant expansion cap when starting the engine after refilling?
 

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Yes, since the heater is part of the cooling system you should put the heater on i.o.t. get rid of air bubbles, but no need for putting on the cabin blower, though.

Usually, I wouldn´t remove the cap after refilling.
 
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