Mystery Water Loss HELP

[eljay]

Hello
I'm doing this for my son who is not car-savvy.
He's bought this 2003 Quattro TDI that is losing slight/irksome ammount of coolant. (It's too late now to reject it)
No obvious leaks or puddles.
He's had it looked at by supposed "Audi experts" ....no answer"
He tried a Rold "sniffer" tester  (to test for cylinder gases in coolant-Head Gasket Failure) ..... It did NOT change colour ....so negative on Head-Gasket failure.
I'm thinking.....
(1) Possible EGR Cooler???
(2) Through phone-video (at normal engine temp) I could see nearside rad-fan running ....but offside fan stationary....Is this normal???
(3) The car is aged and cheap ..... should he just add some radweld?
(4)Would that fix an EGR cooler-issue?
(5)Any other ideas????

HUGE THANKS
Len
 

[Steve Q]

I know you've done the head gasket test but is there any white smoke coming from the exhaust? 

Also it might be worth getting a diagnostic check carried out to see what fault codes flag up. 

Egr coolers are a common failure on VAG cars. I'd advise a good quality replacement as cheap ones can fail quite quickly

[eljay]

Thanks Steve,
I've asked my son about white smoke & he wasn't clear..... I'll ask again.
He has a basic code reader so I'll ask him to do a scan.
The only EGR-valve I've touched (Mondeo) had no cooler so I don't get how one could leak? But....
(1)Might Radweld fix it?
(2)Is the only-one-fan-turning correct for normal temp? 
I mean what is the stationary off-side fan? Extreme Temp? Oil-Cooler?

Many Thanks again

Edited March 15, 2022 by eljay

[Steve Q]

Definitely worth checking for the smoke. That's great, as any fault codes my help rule out potential causes. 

I believe all VAG cars have an egr cooler with the egr. I've found this link, I appreciate it doesn't relate to your specific engine but it gives good info on egrs. On reading it, it could just be a gasket leaking. I do feel you could try rad seal but if it did work then irl would only be a temporary repair. 

https://www.vwaudiforum.co.uk/forum/showthread.php/196553-2012-A6-quattro-3-0Tdi-EGR-coolant-leak-advice

[eljay]

Thanks Steve,
Any thoughts on the only-one-fan turning question?

[Steve Q]

Honestly I'm not sure, but I imagine both should work if you've got 2 fitted. If it's not working it could be down to a failed sensor or broken wire maybe?