coolant filling advice, please

[mlewington]

Have a leaky rad. on my 2001 tdi 130. Existing coolant has all drained away (alarming STOP display on dash!) so I need to fill the system, if only to get it to a garage. Tried just topping up the (empty) header tank but it only took about 500ml of fluid which makes me think that I should bleed the system. I know (thanks to Mr Haynes) that I need to partially pull off one of the hoses leading to the heater matrix to do so but cannot shift it - I'm a bit nervous of snapping off the securing clip, too. Any tips out there?

[snapdragon]

How do you know it's all drained away, and not just the header tank?
Have you tried undoing the stop **** on the bottom of the radiator, I think it's on passenger side of a RHD car, and you need to remove the foglight grille in bumper bar. If you drain it this way you will know how much came out and how much goes back in.

[mlewington]

By undoing the stopcock I guess I'll be draining the entire contents of the system, which I was hoping to avoid! Ane then won't I still need to bleed the sysem when I refill, anyway? Is there perhaps a way of checking whether the cooling system has air trapped in it without bleeding?

[adamss24]

By undoing the stopcock I guess I'll be draining the entire contents of the system, which I was hoping to avoid! Ane then won't I still need to bleed the sysem when I refill, anyway? Is there perhaps a way of checking whether the cooling system has air trapped in it without bleeding?

Hi, the cooling system on modern cars its self bleeding, all you have to do is rev the engine until it gets warm with the header cap removed until all the air is out of the system. Replace the cap and keep an eye on the temp gauge until the fan kicks in- that means that the thermostat oppened and whatever air is still trapped in the system should be in the header tank. Let the engine cool down and fill up to the max mark with the right coolant- G12 spec. Keep an eye for crusty red deposits and stains on and arround pipes= giveaway clue for leacks. Hope this helps.

[mlewington]

thanks adamss24, that's very helpful. Ta.

[snapdragon]

You said all of the coolant had drained away.
So I meant open the **** to see if it really has, if you find it hadn't, then you will know that the 500ml you added was OK.
Then all you have to do is get some G12+ coolant from the dealership and mix refill.

If you have a leak, you may want to get that fixed as this coolant is expensive.

Also, if you do refill, it's best to refill with clean plain water, start and warm engine and heater and empty again and repeat twice.

Never add cold water to a hot engine or it may warp, you can use very hot water 60 deg c or higher to speed things up.

Also, when you refill the final fill, find out the capacity, and add half of that with neat antifreeze, then top up with water for a 50;50 mix. other wise the plain water already in the heater core etc.. will dilute your coolant if you add it ready mixed.