# Gaggia classic broken thermostat



## TomHughes (Dec 16, 2019)

After burning out my thermostat for the espresso side of the classic I thought I'd replace the thermostat. 
However I stupidly sheered it off!

Any ideas how best to fix this? 
drill it out? 
currently having to temp surf a lot to not burn the cr4p out of the espresso!

I've got a sage duo temp but I'd like to get the classic up and running again


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## MartinB (May 8, 2011)

How much thread is exposed if any?


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## TomHughes (Dec 16, 2019)

MartinB said:


> How much thread is exposed if any?


 There is a small nub of 1-2mm left on the thermostat, enough for it to sit and locate in the hole but not enough to screw in


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## ratty (Sep 22, 2019)

Centre punch the centre of the broken off part first.

Carefully drill it out with a small drill bit to start with, and gradually build up sizes.

When you're near the size it should unscrew with a pick, being weakened due to the hole in the middle of it.

Failing that get close to the size (without drilling the threads in the boiler of course!) and screw a stainless steel bolt of the same thread size down the boiler thread, in effect, recutting the thread as it's a softer aluminium.

This has worked for me in similar situations.


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## El carajillo (Mar 16, 2013)

TomHughes said:


> After burning out my thermostat for the espresso side of the classic I thought I'd replace the thermostat.
> However I stupidly sheered it off!
> 
> Any ideas how best to fix this?
> ...


 You will need to remove the broken piece of thread. Initially you can try tapping a narrow (electrical) type S/ driver into the broken piece to try and for a slot to enable you to unscrew the broken stub.

Alternatively you could use a fine drill bit to form a blind hole and then use a fine screw /stud extractor to unscrew the broken piece.

You will need the thread in the boiler to attach the new T/ stat. DO NOT DRILL RIGHT THROUGH INTO THE BOILER/ WATER JACKET


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## TomHughes (Dec 16, 2019)

Thanks chaps! 
I'm on gardening leave till February so I should have some time to sort it!


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## ashcroc (Oct 28, 2016)

Is it the brew stat on the side or the steam stat on top? If it's the steam stat, you could just leave it & fit a PID.


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## TomHughes (Dec 16, 2019)

ashcroc said:


> Is it the brew stat on the side or the steam stat on top? If it's the steam stat, you could just leave it & fit a PID.


 It's the brew stat on the side.

ill dismantle it tomorrow and post some pics.


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## El carajillo (Mar 16, 2013)

TomHughes said:


> It's the brew stat on the side.
> 
> ill dismantle it tomorrow and post some pics.


 And do not over tighten the new one :classic_biggrin:


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## Iwan (Jul 12, 2019)

I did this yesterday! Managed to get it out by using a jewellers screwdriver and hammer to make an indent in the sheared bolt, and then unscrewed it with the same screwdriver. Much easier than expected.


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## TomHughes (Dec 16, 2019)

Iwan said:


> I did this yesterday! Managed to get it out by using a jewellers screwdriver and hammer to make an indent in the sheared bolt, and then unscrewed it with the same screwdriver. Much easier than expected.


 Awesome! I'll give that a go!


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## ratty (Sep 22, 2019)

Yes, good one with the screwdriver Iwan.

The broken off piece is brass, so it's a soft material similar to aluminium depending on the alloy mixes.

Applying some direct heat might do it too, as aluminium expands faster and more than brass. Not too much heat though, or the aluminium will melt!


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## TomHughes (Dec 16, 2019)

Ok I'm not going to say exactly what I did as it is frankly embarrassing, but clearly when I did this (about 5 years ago) I decide to just try and ream the thing out! There is no way the original broken section can be removed or that anything resembling thread is left.

But...

What I did before was to sit the thermostat with the nubbin in the hole and used blue tac to hold it in place.

Based on some temp measurements thus seems to be still conducting the heat from the boiler (as the thermostat is sitting against it) and causing the thermostat to trip the switch when it reaches 100 or so degrees, which I presume is so the water comes out 93 at the group.

When I remove the bluetac and the thermostat falls away from the boiler it continues to heat beyond 110 to make steam wand temp.

Does this sound logical?

It was really interesting measuring the incredible temp fluctuations of the gaggia though, 85-100, which I guess why the PID is an upgrade!


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