Water as coolant.

it's a stupid question you need to put water into the engine to stop it from boiling up you need to have antifreeze in it to stop the block from freezing and possibly cracking you need to have some sort of rust inhibitor in the coolant mix to make sure the insides don't rust out if there is no water in the system, leave it open so as to now risk cracking the block or popping a core plug out when it's cold putting hot water into an engine is not going to stop it from getting cold if anything you should put some antifreeze in it if you are going to put water in it, and then run the engine to get it around the block and stuff

Oh dear. It seems I missed the most important bit. 'for a quick trip to the shops, to get some proper coolant'.

In that case no, it won't be a problem provided you bleed the system properly before you set out. Then remember to drain it fully because I bet you didn't measure how much came out.

you can run it on water to go to the shops to get some antifreeze.

mrcheerful

Not for any other purpose of short journeys though. Engines can be picky like that.

I seem to recall water is more efficient at cooling than antifreeze so in theory with 100% water it will even run cooler - however, the anti corrosion and antifreeze properties of plain water are somewhat non-existent, so best stick some antifreeze in double quick sharp, especially considering the weather here at the moment :)

Hellraiser............>

If the air temperature is below freezing you can easily get the radiator frozen even though the engine is boiling due to the - now - lack of water circulation. So don't drive it while the air temperature is that low.

Rob Graham

Not doubting you or anything, but race motorcycles (and cars?) have to run on water (in case of a spill). So why do you say engines be picky?

Race engines aren't usually run in freezing temperatures. Or for tens of thousands of miles.

And get rebuilt fairly often, with corroded bits cleaned up or replaced.

And have better coolant flow.

And I'm sure many other differences.

You obviously missed the sarcasm. Other guy said that it's fine for short run to the shop to get some antifreeze, and I said that it might not be ok for other types of short journey. It loses the humour when it needs explaining. That's if there was any there in the first place...

D'oh :) I see it now!

And as the now frozen radiator water starts to defrost, it expands and blows the rad.

:) as others have said, this won't be a problem :) but, as at least one person has mentioned, youwould have to probably drain the system and refill it with the correct amount of premixed antifreeze/water solution :)