How to change your inline thermostats.

[pudding]

Have a check around the plastic flanges that attach to the block under the chain cover, above the gearbox.  There’s an O ring that likes to go hard and leak.  The KO4 engines also suffer from a slight head gasket weep from the rear corner (pass side) of the head, which is what mines doing.  Mine takes about 6-9 months to drop from max to min.

[Newbieintown]

Guys does anyone know how much coolent it would need to fill back up the system? Also are there any bleed nipples to get the air locks out? Thanks

[andyiseddy02]

About 2 litres.

[Octoparrot]

So I went to change mine today thinking it'd be a nice easy job. It was, there isn't one! Which is a bit of a bugger as it means I'm going to have to delve into the depths and change the main thermostat.  if anyone needs a genuine inline thermostat drop me a pm £20 posted. By the way mines an 06 manual BWA.

[griff30]

  Cheers for the info Pudding. Didn’t know I’d have to undo engine mount to remove alternator though... changing thermostat took 5 maybe 10 mins on my old mini!     
max amplitude:  VW call the inline ones “coolant regulator” or something very similar. They first told me only one but then when we looked I recognised the shape of the part under that name. But now it looks like I don’t have one anyway...

[pudding]

No worries.

Yeah I also have a spare inline thermostat 

The main one is easy once the alternator is off.   It's a great opportunity to check / replace the serpentine belt, alternator clutch pulley and the electric after-run water pump 

[shaunK]

Does anyone have a part number for the main thermostat? Thanks

[Ollieeee]

So I went to change mine today thinking it'd be a nice easy job. It was, there isn't one! Which is a bit of a bugger as it means I'm going to have to delve into the depths and change the main thermostat.  if anyone needs a genuine inline thermostat drop me a pm £20 posted. By the way mines an 06 manual BWA.

Bit of a thread from the dead but I’ve just had exactly the same thing. Went to change the inline down the front of the engine and there isn’t one! 55 plate manual so I’m pretty confused. Did changing the main stat solve it for you?

[Octoparrot]

Yes changing the main thermostat cured the problem completely but I did also change both temp sensors at the same time as well just to be on the safe side. Car hits 90 degrees and stays there regardless after about 3 miles.

[Ollieeee]

Yes changing the main thermostat cured the problem completely but I did also change both temp sensors at the same time as well just to be on the safe side. Car hits 90 degrees and stays there regardless after about 3 miles.

Great stuff, fingers crossed then.

[Jamesf1010]

Hi there, I've just acquired a 2007 GTI a couple of months ago and been having the same issue with the temperature gauge dropping.

I had the main thermostat replaced by a garage last week but this hasn't resolved the issue. It generally takes a good while to heat up and usually falls back when on the motorway / over 50mph.

I have looked at the 'secret' climate control menu the past few drives and it tends to be sitting around 66-70 degrees Celsius. It has been up to the high eighties but that was after a decent drive then sitting stationery for a while.

My heating works ok and have looked through the other threads and can't really see what else might be causing it other than a second thermostat also needing changed? Would changing the sensors be likely fix this or any other ideas as to what it might be?

I'm taking it back to the garage this week for another test but apparently there weren't any faults showing up last time that would have indicated a problem here so not sure what the next step is.

Any other ideas would be much appreciated.

Cheers