sounds daft, but where is the thermostat on my car? 8v digifant

[ramps]

As the title, I feel a bit daft asking but i cant find it haha.  :embarassed:

The car is fine to drive normally but when expressing its performance its seems as if the thermostat shuts and stops letting the hot water circulate, I get this from the heaters just going cold. Pop the bonnet and water is firing from the overflow on the header tank. once cool if i top up the coolant and re bleed it all is fine until I do some extended expressive driving. tootling around town its fine.

Any other problems it may be please do tell!

Thanks

[VeeDubGTI16v]

the thermostat is bottom left of the engine, behind the pas bracket if you have it

sounds like your heater bypass valve has stopped working though. You see the two water pipes going through the bulkhead, theres a valve connected to both. they have a habit of sticking. have a search on here, loads of threads on it!

[ramps]

yeh but if the heater bypass valve is fooked surely the cooling fan would come on and prevent the overheating?
and why would it only do it when im giving it beans?

[ramps]

Just had a scen and the heater valves already have been bypassed.

[rubjonny]

have a read of the coolant faq in the maintenance section, covers all the tests you can do.  just having low coolant is whats causinbg the heaters to go cold, this is how I knew I had to top up the water in my 1.6 
common issue on these is the header tank cap, new blue one is cheap so worth doing after you've gone thru all the faq tests.

[JimR]

As said, on a digi just follow the bottom rad hose to the bottom of the engine where you'll find a little elbow bolted to the bottom of the block, unbolt the the two 10mm bolts and et voila.

[Diamond Hell]

Drain the coolant, flush the system (especially the rad) out and refill.  See if that makes any difference.

Sounds as if the system's succumbing to old age, unless you know whether the rad and heater matrix have been replaced at any point.