Draining the coolant system

OK, I just got the car back from the service. they mentioned that the coolant was weak and offered to change it for £40, I said I would top it up myself.
On checking the coolant I see that it is brown, think weak tea without milk.
I think that this indicates that the coolant has been mixed, or just filled with water - I hope not (luckily it has not been too cold this winter).

Anyway it does look like a drain and refill job, so does anyone know where the engine block coolant drain plug is?

Oh, and what is the coolant capacity on a 1.4 TDI?

hi ar2ro
if i where you i would drain all the weak tea out and refill if you take off the the top and bottom hoses from the engin and rad
The coolant capacity on the 1.4tdi 75bhp and 90bhp is 5.0 lts
and is 5.6 lts on the 1.6 fsi and 1.4
cheers
robin

OK, removing the hoses is easy enough, I will flush it out too.

Hi Au2ro
I have just changed the coolant on my TDi when replacing the water pump. The bottom hose has an o.ring seal (I replaced this but it looked ok) and the moulded end is held in place with a wire clip. I was rather dubious about removing it but everyting came off and went back quite easily. The manual also recommends removing the 2 small coolant hoses which supply the oil cooler head, below the oil filter. This drains a lot of coolant which would otherwise be trapped in the system.
I'm pretty sure there is no drain plug in the cyl block.
Use genuine Audi antifreeze.
Judging by the colour of the coolant, if you have the time, backflush the radiator as Robin suggests then fill the system with water, run it until the thermostat opens, let it cool down the fill it with the antifreeze mix.

Cheers Spike

Removing the hoses is easy enough, yea right!

If I could even get the under tray off, 'the air con exhaust pipe'? bolts are corroded so I can't even get at the bottom hose.
The top hose connecting to the radiator has some funny kind of clip/plastic fitment attachment, which won't come off, I am afraid to force it in case the plastic breaks. No jubilee clips to be seen, just those wire clips that spike was dubious about.
My local friendly garage can't even get at it, so it's back to the VW garage, oh but wait they are fully booked till next week.

Now I was thinking, if I got some really fine tubing I could snake it through the expansion chamber down into the engine block and siphon off enough 'weak tea' to top it up with at least some antifreeze. Is nothing straightforward, sigh.

Done, at last.

Well I got it done at last.
I took a walk with the dog and thought it through.
There was a clip on the 'the air con exhaust pipe'? (or is it the engine heater exhaust?) where it connects to the outlet attached to the under tray. So I loosened the clip and removed the pipe from the outlet, it was tricky reaching in from above, it's just as well I have skinny arms, voilà, the under tray came off easily.
I don't know why I did not think of this before (neither did the local garage).

Anyway, under tray off and with the bottom hose now accessible I managed to get it off easily (same clip as the top hose, but for some reason the top one would still not budge).
I could not manage to remove the the 2 small coolant hoses which supply the oil cooler head, they were stuck on fast. But I managed to flush the system twice and with no more weak tea left managed to refill with 2l of antifreeze and 3.5 l of water. I guess there was still 1.5 l of water in the oil cooler head, but since I flushed it twice I am quite sure that there would only be clean water left.
It's a while since I worked on any car, I used to do this kind of thing quite often, I had forgotten what a sense f achievement it gives you once it's done. I can't help thinking it should have been much easier though.