Audi A3 - Slight Coolant Leak

[am1994]

Hello everyone, few months after I bought my Audi A3 1.8L, I noticed a small coolant leak and since then I've had to top it up with around 100ml of coolant every month or so.
Yesterday, I decided to take the car to the mechanic  to see if he can spot where the leak is coming from.
Initially, he thought it was the radiator, but after the put the car in the ramp and did a coolant pressure test, it appears that the leak is coming from that small black item in the picture and it might be also dripping from near the engine.
I haven't noticed any coolant smell or white smoke from the exhaust to suggest head gasket leak.
Does anyone know what that black item might be? Thermostat/water pump didn't seem to have any coolant residue
The mechanic told me that if I want to do a further check on the coolant leak, the intake manifold will have to be removed. That would alone cost me around 300-400 GBP and I don't think is worth going that route for a 15 year old car.

Edited January 13 by am1994

[garethw]

Not an answer to your question and... I might get lambasted for suggesting this but...

I had a leak on mine that my mechanic had repeatedly failed to address so I threw a container of radweld in and that seems to have fixed the issue.

I know some people don't really like it but it does seem to have worked.

[am1994]

Hey Gareth - was your coolant leak on the same part as mine?
It actually crossed my mind to buy radweld but when the mechanic removed the engine undertray, he found orange glittery stains on it.
That suggests that the previous owner might have used something similar to stop the leak.
I might give radweld a try, otherwise I will probably change the auxiliary water pump which will cost me around 100 pounds including labour.
My only concern is that i dont know if changing the auxiliary water pump will solve the issue.
 

[garethw]

Hey,

I never identified the source of the leak. I have previously had the water pump replaced (which I understand is a common issue on these engines) but not sure if that was the auxiliary one or a different one?

I would always rather go for fixing "properly" but I didn't have the time to get the car booked in so went for quick and easy.