Dear members

Tomorrow (Wednesday 7th January) I should fit a new thermostat to my car due to a low reading temperature gauge and no DPF purging for the past few days - at last the rad fan is getting a well-earned rest! Fortunately the ambient temperature has risen so the frostbite problem has gone away, however it has now started raining here in Bournemouth UK - which must mean snow and ice problems further North.

I have a new FEBI thermostat and rubber 'O' sealing ring and understand I need very thin but powerful fingers and plenty of sticking plaster to get to the 'stat which is in a complex-looking plastic housing with lots of hoses branching off, fitted above the clutch bellhousing. From what I can see, that coolant housing has to be split in the middle to get at the thermostat and I also plan to fit a new coolant temperature sensor which looks just as challenging. It looks like the 'stat housing is made with some kind of turn-off joint which I assume will need the the rubber 'O' ring fitting. There are 3 questions arising from this short process if anybody can help me please;

1. can I split the 'stat housing in situ or will I need to fully disconnect all hoses and remove it from the car?

2. if in situ, in which direction do I need to turn the housing and any helpful hints on this?

3. judging by the design of the large end of the thermostat it can only be inserted in one position, is this correct?

I have also got the header tank with "mit Silica" helpfully stamped on it so I plan to remove the tank, clean it up and hope to find an unburst tea bag waiting to be plucked. At almost 300k miles I am probably being a little optimistic on that score. I do have a one-eleven which it appears from the forum has a setting to make it a bit easier to bleed the coolant system before I frolic up any motorways, I will need to find where that sits in the menu system. Such fun!

May I wish everybody reading this a successful 2026 without world wars, without a personal visit from Orange Man to declare your home the 93rd State of America, but at last a more prosperous future beckoning.

Really hoping to have any answer(s) today,

Mike Wattam

I ve got the same issue..... awaiting a new o ring for the pressure boost pipe where it meets the throttle body, does a scan show a sensor fault? i ve been advised not to replace that if no codes.....

Well done on 300k, mines at 142k and i'm hoping to get to 200k....

This guy appears to have done it ok but other vids on the Golf tdi say remove throttle body for access, the Thermostat can only go in one way, has 3 tabs that need to line up, i plan to make the existing one once i get the housing apart... Autodoc say there is another thermostat in the cooling system but local Skoda dealer say only this one.... looks like a rocket...

Edited 8 January8 Jan by adg1

HI there,

The 'rocket ship' thermostat (according to my trawls for somebody who could actually supply one) was only fitted for a short while on early series 3, being superseded by a more complex 2-'stat system and I suppose they had their reasons for that, I don't know. Perhaps more experienced members of the Forum know - please step forward?

There is so much 'gubbins' around that area on the car, I can understand why you want to strip out more to gain better access. My experience of VW Group cars is that the environmentalists got very enthusiastic about making 'new' parts from recycled plastic, but due to poorly controlled material content often dries out prematurely in that adverse environment. This means that when you disturb anything, 10 year old plastic tends to fall apart and if it results for instance in pipes hanging loose, that could lead to a future problem. VW were never very good at designing anything for easy access in service but they are not the worst in this respect - yet the very best when it comes to reliability in service over the years.

Slow-moving parts such as the 'O' ring are generally in very short supply and even the OE manufacturers are notorious at the moment for having nil stocks at their factory, at UK warehouses and at the dealer network level. VW Group in the UK have a semi-independent network of parts wholesalers called TPS, they supply independent car repairers but if a ordinary person such as you or I try to approach them, they treat us as too 'dirty' to even talk to, let alone sell to. You might find a friendly person if you try phoning round their various locations.

Consequently I believe you have 2 alternatives; either do not remove the pipe to gain better access, or remove it hoping not to damage the old seal - a good soaking in a silicone-based oil (but NOT WD40) and 'Gently Bently' should help you achieve that. Alternatively try independent wholesalers such as on eBay who sell Febi-Bilstein parts (which are generally of OE quality). Be very careful when ordering parts as VW Group vehicles changed specification and part numbers very often which tends to make parts finder searches by independent part suppliers inaccurate. Local parts suppliers could be helpful if they have a 'free returns' policy in place. Much as I like Amazon in general, their car parts finder appears to be way off beam for anything other than routine maintenance parts, so do your research thoroughly and cross-check.

Nobody so far has come back to me to let me know about how to split the 'stat housing and whether I'm being optimistic to open it up without breaking the plastic.

Mike Wattam

Mine is 2016 model & has what i would call the rocket ship stat, as per video, gave vin/reg to Skoda dealer, he carried them in stock, its also what GSF and ECP specc'd as well, it was only autodoc that said there was a 2nd stat, more conventional looking... but no idea where that is.... its not only any parts diagram i ve seen.

I got the o-ring really easily, off a VW garage, in stock.... its winging its way to me, TPS deal with the trade, so i wouldn't expect to be able to bypass retail mark up.

Do you have a photo of your housing? this is what Skoda say i have got, car is a 1.6 tdi Greenline, so has more emissions stuff...

I have to say though that unless the removal of the pressure pipe gives better access, mine will be going to a garage!

Edited 8 January8 Jan by adg1
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