Coolant leaking from thermostat housing.

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F41XTH
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Coolant leaking from thermostat housing.

Post by F41XTH »

I've finally had time to identify where the coolant is leaking out from, it appears to be between the thermostat housing and the block. As seen in these photos, it's been eating away at the shield for some time.

I tried to tighten the bolt but didn't want to force and snap it. Do I get a new housing? Just remove, clean and reseal the existing one?

It's only a minor inconvenience right now, but we all know that one 20 minute job turns into a 5 day ordeal if a bolt snaps off
'88 1.9 78HP Petrol WBX

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Aidan
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Re: Coolant leaking from thermostat housing.

Post by Aidan »

remove and inspect and then probably clean and reseal, the o ring isn't expensive so expect to replace. Overtightening the bolts can crack the housing, 10Nm I think is enough. Corrosion of the block at the mating face can be an issue.

Are you sure it's not coming from any of the hose connections ? Jubilee clips aren't the best for these connections, originally they were sprung clamps specifically sized for the job, but they often get damaged or lost or are too rusty to want to reuse
AIDAN :)

F41XTH
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Re: Coolant leaking from thermostat housing.

Post by F41XTH »

Possibly. It's hard to get a proper look. It slowly weeps out from the bottom but I just can't identify the source point for sure.

I do need the van on weekends so I'm slightly reluctant to try to remove the housing in case it breaks or the bolts snap. Should also probably have a replacement on hand before even attempting to remove.

I'll try and get a look from the top down of this weather ever breaks
'88 1.9 78HP Petrol WBX

F41XTH
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Re: Coolant leaking from thermostat housing.

Post by F41XTH »

It's finally time to sort this leak out, it's losing too much to just ignore it. It's definitely coming from between the engine and the housing. Is it better to just replace the housing, thermostat and obviously all the seals and gaskets rather than just try to replace seals and gaskets?

https://ibb.co/1fx3XyF1
https://ibb.co/rGjZWstk
https://ibb.co/HTXSxHRM

Should I just get this?

https://www.justkampers.com/thermostat- ... -1992.html
'88 1.9 78HP Petrol WBX

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maxstu
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Re: Coolant leaking from thermostat housing.

Post by maxstu »

Cheaper to buy from Brickwerks the 2.1 version and block off oil cooler outlet.

https://brickwerks.co.uk/wp-content/upl ... 06600_.jpg
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F41XTH
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Re: Coolant leaking from thermostat housing.

Post by F41XTH »

maxstu wrote: 30 Dec 2025, 16:10 Cheaper to buy from Brickwerks the 2.1 version and block off oil cooler outlet.

https://brickwerks.co.uk/wp-content/upl ... 06600_.jpg

Forgive me, but is that easy to do?
'88 1.9 78HP Petrol WBX

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maxstu
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Re: Coolant leaking from thermostat housing.

Post by maxstu »

Yes. A bit of small pipe. Jubilee clip over oil cooler outlet spigot. Small bolt in the open end of pipe and another jubilee clip.

https://brickwerks.co.uk/product/thermo ... ternative/
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maxstu
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Re: Coolant leaking from thermostat housing.

Post by maxstu »

Note at bottom of link the other bits you may need. Almost half the price compared to JK.
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mioba
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Re: Coolant leaking from thermostat housing.

Post by mioba »

maxstu wrote: 30 Dec 2025, 16:20 Almost half the price compared to JK.

Like everything from JK
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Re: Coolant leaking from thermostat housing.

Post by PaulFDennis »

Did you resolve the issue with a leaking thermostat housing? I ask because I’ve just identified and fixed the leak from mine. It wasn’t the housing, pipes, jubilee clips etc., but the ‘o’ ring seals for the temperature switch and sender units. Both seals looked to be slightly undersized in cross section and the senders had been coated in instant gasket/sealant. A quick and cheap fix at just 60 pence for each ‘o’ ring from Brickwerks.
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