Which thermostat to replace?

[Dave_d]

Hi guys, I believe I need my thermostat replacing on my 07 gti, I understand it has 3 with it being a dsg, does anyone know how to tell which one will need replacing? I drove to work this morning which is 11 miles at average of 30mph and it had only just reached around 75degrees

[Leco_GTI]

Main thermostat. Once it's replaced, if it takes too long to reach temperature then you will need to replace the two inlines too. I am talking by experience 

[lukemk5gti]

A more detailed description as I've done all mine in stages to identify what causes what.

MAIN THERMOSTAT
The car never reaches temperature unless idling in traffic. Usually drops in temperature when coasting down a hill
Big job to replace this one circa £200 - £400

INLINE THERMOSTAT
The car takes ages to heat up. Often 30 solid minutes of motorway driving for me but once it does it stays at 90deg.
Easy to replace and a definite diy job. Right at the front of the engine with room to get hands in.

DSG
No experience as mine is manual but probably not a big deal.

My advice, check your symptoms again. Go for an hour long drive and see if it reaches 90 eventually. That means you can get away with the cheap inline fix.

If it doesn't reach 90 then unfortunately it's the main and quite possibly the inline too. Since the inline is only around £15 with negligible labour I would get both done together.

[Leco_GTI]

The symptoms described are spot on. A DSG has two inlines.

[Shoduchi]

The symptoms described are spot on. A DSG has two inlines.

Depends on the year, 2008 have only 1 inline.

It has been explained in the forum before.

[Leco_GTI]

The symptoms described are spot on. A DSG has two inlines.

Depends on the year, 2008 have only 1 inline.

It has been explained in the forum before.

Thanks for letting me know. I wasn't aware of that 

[Dave_d]

ID be more inclined to say the inline thermostat needs replacing, as it does eventually reach temperature. Once it's there it stays there. Just takes yonks to get there