how to change thermostat

richard165

silly question but whats the best way of changing thermostat and cts? how does the thermostat seal? Will I lose a lot of coolant?

thanks

KevinH

To change the cts have a look at this 'resource' by evocarlos:
https://z22se.co.uk/resources/water-temperature-sensor-change.72/

A new genuine GM thermostat (part # 12622410) comes with a rubber gasket which locates around the thermostat (I think I've got a pic somewhere so I'll post it up for you).

You will have to partially drain the coolant - the Zafira's may have a drain tap on the bottom left (drivers side) of the radiator (in which case it is easier than removing the lower radiator hose). Then undo the two thermostat cover bolts (M6x20) with a 10mm socket (ensure the engine is cold to prevent stripping the threads), there may be some coolant spillage then lift the thermostat cover and retrieve the old thermostat. Fit the new thermostat with the rubber gasket attached, replace the cover making sure the two surfaces are clean and tighten the bolts to 10Nm (the rubber gasket fitted around the thermostat will seal the cover to the body). Ensure the radiator drain tap is closed and the heater is set to hot, then refill the system via the expansion tank to the 'max' mark with long life coolant (orange-red in colour). Leave the cap off expansion tank, start engine and check for any leaks - let the car idle and get up to operating temperature so that the thermostat opens (around 82°C), and gently squeeze the lower hose to dispel any air (burping) that may be in the system, Lastly check the expansion tank level and top up if necessary (not forgetting the cap).

Hope that helps 🙂

richard165

thank you very much!

KevinH

Pics of the latest cooler running thermostat.

richard165

why have a cooler thermostat? I don't see the point?

I changed it today the car stays warm and doesn't cool down when I use the heater, crucial for winter!

it was a fiddly job to get the bolts back in upon reassembly, my socket is not magnetic, therefore a pick up tool was used a couple of times!

I've definitely done easier ones!

Thank you again for the advice!

KevinH

Glad you managed to replace it OK (y) (yes a fiddly job)

Out of interest, did you replace with genuine or aftermarket?

richard165 said:
why have a cooler thermostat? I don't see the point?

Not too sure why they changed to a cooler rating, but I know that the thermostats were renowned for the inner seal deteriorating which allowed the coolant to bypass the stat (having a similar effect to the thermostat stuck open). Maybe running cooler extends the life of the seals :confused: :unsure:

richard165

that's exactly what happened to mine. good as new now though!

I replaced it with an aftermarket, about £8

KevinH

Did you manage to replace the cts too?

richard165

no, took a look but thought I'd see how thermostat was working to make certain it was the problem

KevinH

Presumably the car was taking a while to warm up then?

Also, I see you have managed to reduce your oil consumption issue

Good work (y)

richard165

Thank-you!

yes it was, not good towards winter lol

fingers crossed its reduced it lol!(y) im going to report back after 500 miles where i would have used .75l of oil :jawdrop:. im frankly amazed that it made a difference but the seafoam was worth a try before considering more invasive options.

funny thing about that was a soon as that seemed to have made a difference, the oil level sensor decides to spring a leak:mad:. too cold to remove sump now so I just rtv'd it up.

its just one thing after another!

just a change to synthetic oil and that is it:whistle: semi synthetic feels dirty thanks to you and berto!

richard165

I've gaff a bit of a problem, after a long motorway journey, I discovered that there was coolant dripping from the passenger side of the radiator.

there aren't any visible leaks, but I remember that I over filled the coolant, as it kept going down after air was pushed out and I never siphoned out the excess. there is no coolant around expansion cap.

please tell me there is a pressure valve somewhere that released the excess!

this has happened before but the leak magically stopped.i over filled the coolant then too:unsure:

sinisa97

@[deleted] Hello, did changing the thermostat resolve your issue with engine taking a long time to warm up in the winter? Thanks

richard165

yes, it was an easy job too