Chase the water leak!!!

[Paul Seed]

So, after my 150 quid A4 blew before xmas, got hold of a 05 plate A4 Cabriolet B7. When I got it, had water rather than G12/13, so kind of knew there were things going on... Found a small leak on the Rad, but liveable.

About a month back, started losing more fluid from the radiator, and it blew 2 of the hoses (to and from oil cooler). Replaced the hoses and radiator, and all seemed ok apart from a small leak when I was refilling (although this seemed to stop)

Fast forward a drive or two, and the car is dumping water when cold, but when its warmed up slightly, you can top it up and it will be fine for the day. So attention turned to the Thermostat (which i've started switching out today).

Problem is, didn't look like it is coming from thermostat but appearing at the front of the car by the aux belt..

Don't really want to tackle the water pump, but does anyone think its going to be that?

 

[Sygh2k]

petrol , diesel?

common fault
https://www.audi-sport.net/xf/threa...rear-coolant-flange-replacement-guide.305734/

 

[Paul Seed]

1.8t Petrol Model. Sorry - thought i'd thrown that info in!

Got the thermostat off so i'm committed to that!Just not sure I can bring myself to the pump and belt.

Thanks for the link to the article - That side is fine - Did the temperature sender as the dial was erratic (didn't know whether it was the sensor, or air bubbles getting sensed.. Not sure if it reacts that quickly...)

Since the initial work on the rad and hoses, the temp dial seems to behave itself sitting at 90 when warm, but does seem to waver a little (just either side, hardly noticeable). On warming up however it has been fluctuating, particularly around 50/60 degrees (dipping up and down before heading to 90 and staying stable)

 

[Paul Seed]

Should also mention, the water appears pretty central in the car - Dripping down by the oil sump.. But doesn't seem to be far enough over for the water pump

 

[Sidrick]

Can you pressurise the system or access a ramp to take a look underneath while running? The emphasis should be on diagnosing the issue rather than replacing parts until you strike it lucky.

 

[Paul Seed]

Can you pressurise the system or access a ramp to take a look underneath while running? The emphasis should be on diagnosing the issue rather than replacing parts until you strike it lucky.

Yes - System stays pressurised when running - Leaks if the engine is cold and you try and top it up.. Run with the expansion tank open and let it draw in, the leak stops and will stay stopped until engine is off and cools.

Thats the main reason I thought thermostat, as once its up to temp, it holds (although after a lengthy drive, you can hear the hissing of the pressure getting out somewhere)

 

[Sidrick]

Yes - System stays pressurised when running - Leaks if the engine is cold and you try and top it up.. Run with the expansion tank open and let it draw in, the leak stops and will stay stopped until engine is off and cools.

Thats the main reason I thought thermostat, as once its up to temp, it holds (although after a lengthy drive, you can hear the hissing of the pressure getting out somewhere)

Sorry, I wasn't asking if it pressurises, I was asking if you have access to tools to pressurise the system while being able to see where the leak is? eBay kits to do this are cheap enough but it sounds like paying a few quid for a garage to do a cooling system pressure test may save you a few quid in the long run.

If you can hear an audible hiss but can't find where it's coming from then I'd definitely bite the bullet and enroll help before replacing parts that may or may not solve the problem.