A relatively mess free way of draining the cooling system

[Dominic]

Hi folks
A few months back, I drained the cooling system prior to fitting an unleaded head. The usual problems occurred, the tap on the block is clogged, not so much as a drip emanated from that orifice! There is no tap on the radiator either, so rather than swimming in a sea of coolant, I cut up an old bicycle inner tube, which fits perfectly over the bottom hose connection on the rad. After releasing the cap and top hose, it drained straight into the bucket with hardly a drip on the floor! Hope this might be of help to others,
Dom

[simmitc]

That sounds good, but I don't quite understand how you got the inner tube on the rad without removing the bottom hose; and once you've removed the bottom hose, what stops the coolant from falling out of (a) the hose and (b) the rad - or is this why it's only "relatively mess free"?

[Dominic]

As long as the radiator cap is on tightly, (and you move quickly!!) spillage is minimal. The hose needs to be directed into a suitable container as quickly as possible. Atmospheric air pressure is what is actually holding the water in place in the rad. It is the same principle that can be observed by filling a pipette, holding one's finger over the end and retaining the fluid until the finger is removed. The principle can also be demostrated in a fun "trick". If a drinking glass is filled to the brim, and a postcard carefully placed on the top, so that no air whatsoever remains in the glass, the glass can be inverted, with the card and water staying in place! It sounds improbable, but it does work! (Usually!!) Try it, (at your own risk, no claims for damaged carpets will be considered!)
As for "relatively mess free"... a few cups of water is a small proportion of the full 6 pints (or thereabouts) capacity!