Hi there, I'm new to this club and I'm hoping I can get some much needed help and info. 

I've got a 2007 A3 2.0tdi 170 and I've recently had a cooling problem. I'm loosing coolant from my expansion bottle I think as I can hear it dripping onto the manifold after I drive it. Its in the garage atm and they have checked the egr valve and it's not that, the garage is baffled aswell as my self. Has anyone any idea of the problem. Thank you for any info. 

Stuart.

You wrote that you can hear the leak dripping, but have you actually looked? Where specifically is it leaking from at the expansion tank? The cap, the hose connection, a hole in the side, somewhere else?

air  con  dumps  water to  after   run     kev

On 6/19/2021 at 5:42 PM, cliffcoggin said:

Stuart.

You wrote that you can hear the leak dripping, but have you actually looked? Where specifically is it leaking from at the expansion tank? The cap, the hose connection, a hole in the side, somewhere else?

Garage say its coming from the expansion bottle cap when under pressure but they have put 2 new caps on and a new bottle and still having the water leak problem 

That suggests that excessive pressure is being generated. My guess for the cause would be a leak at the cylinder head gasket or a restriction in coolant flow leading to boiling.

head gasket  yes that  to  water pump to   

Hello Stuart,

If this were mine, I would not be jumping to conclusions, but getting the necessary simple checks done to confirm or refute the assumptions. 
Can I suggest you first get your garage to carryout a pressure measurement on the coolant pressure when the engine is up to temperature. 
Kind regards,

Gareth. 

1 hour ago, Magnet said:

Can I suggest you first get your garage to carryout a pressure measurement on the coolant pressure when the engine is up to temperature. 

Agreed. I would have expected Stuart's garage to suggest it as the next step.