Driving around with just de-ionised water (instead of coolant) for a short time OK?

seatbeltnoob

Hello

I'm changing out to the coolant. It's a vauxhall and the coolant is quite bad. It's old, and hasn't been chnaged for at least 6 years (of OH's ownership), and who knows if the previous owner changed it.

it's quite dirty and sticky. One of the things I read is when coolant is very old it gets very very sticky.

So I'm eager to get out as much of it as I can.

The car holds 5.5L of coolant and only 2.5L comes out when you open the drain plug in the rad. I have done this drain and fill with deionised water (only). twice now. It is quite a lot clear. I plan to do it once more and then fill it up with concetrate so it's just under 50:50 mix. (drain 2.5L, fill with 2.5L concentrate).

A lot of videos advise to idle the car. Based on my experience of idling the car for 10 minutes. the car never gets hot, the thermostate never opens. It's a 1.4L corsa and is designed to be efficient. It needs to be driven to reach proper operaing temp in order for the temp to open. So it needs to be drive.

I am just wondering can I just go about my day and do my errands. And drain and fill at the end of the day. Or is that dangerous for the engine? I heard that coolant needs to have antifreeze so it doesn't boil and turn to steam which can overheat the engine.

born_again

Might as well just use normal tap water. As this is MSE 😜

Try taking top & bottom hose off Rad, shoving a hose pipe in top hose (cloth over end to stop blow back) & reverse flush the system. That will get more out. Even remove stat, even better get a new one as old might be gummed up.

Ganga

Of course you can drive on pure water in the summer ,the anti freeze is only there to stop it freezing in the winter ,also it will not boil and turn to steam ,what i would suggest is drive some where for about 30 mins till the engine gets hot ,park up and after about 10 mins drain the radiator again ,then add the neat anti freeze till the car system is full and as you said about 50 /50 mixture. 

[Deleted User]

I've changed a couple of Corsa thermostats over the years, they do have a tendency to get stuck.
As mentioned above, it's probably worth fitting a new one, since you're doing most of the job anyway.
Last one I bought was around £14 from GSF, so not expensive.

Grumpy_chap

DO NOT USE DEIONISED WATER.
It is very corrosive and will eat everything it come into contact with - you will need a new radiator at least.

You can use simple tap water.  

Mildly_Miffed

Not sure I'd drive it round much.

Drain what's in there.
Take the 'stat out, and flush it through thoroughly, both ways, block and rad, with a normal hose pipe.
Put the OLD 'stat back in, and connect the hoses back up. Fill it with tap water, and run it up to the fan kicking in.
Let it cool, drain it again.
If what comes out is REALLY horrible, repeat everything.
Put a new stat in. Refill with fresh coolant. Drive as normal.

Remember, coolant isn't only "antifreeze", it's anti-corrosive, and where you've got a mix of dissimilar metals, you don't want to let corrosion start.

ElefantEd

Grumpy_chap said:

DO NOT USE DEIONISED WATER.
It is very corrosive and will eat everything it come into contact with - you will need a new radiator at least.

You can use simple tap water.  

Really? I would be surprised if there is a significant difference between the corrosiveness of deionised water compared with tap water (and if there were a difference I would expect tap water to be more corrosive anyway). I would also use tap water, but purely because it's cheaper.

Grumpy_chap

ElefantEd said:

Grumpy_chap said:

DO NOT USE DEIONISED WATER.
It is very corrosive and will eat everything it come into contact with - you will need a new radiator at least.

You can use simple tap water.  

Really? I would be surprised if there is a significant difference between the corrosiveness of deionised water compared with tap water (and if there were a difference I would expect tap water to be more corrosive anyway). I would also use tap water, but purely because it's cheaper.

It is really.
Pure (deionised) water is known as "the universal solvent".  It will readily take up ions from any material it comes into contact with.

Tap water is already saturated with the minerals leached as the water passed through the environment.  Consequently, it has less aggressive properties.

chrisw

Interestingly, Halfords battery top up water is deionised water but 'can also be used in engine cooling systems to reduce scale and corrosion'.

https://www.halfords.com/motoring/battery-maintenance/battery-accessories/halfords-battery-top-up-water-5l-402396.html

SteveJW

Ganga said:

Of course you can drive on pure water in the summer ,the anti freeze is only there to stop it freezing in the winter

Modern antifreeze also contain an inhibitor, this is to reduce / prevent corrosion between the dissimilar metals found within the cooling system

The antifreeze properties can easily be ascertained by trying to freeze a small sample of the coolant, doubt if the average homeowner would have the equipment to test the inhibitor properties of the coolant.

Maybe the old central heating trick of draining a small amount of the water out of the system and putting it in a jar with some nails to see if they rust would be an indicator

Why do they not put a form of antifreeze in central heating systems

Car_54

SteveJW said:

Ganga said:

Of course you can drive on pure water in the summer ,the anti freeze is only there to stop it freezing in the winte

Why do they not put a form of antifreeze in central heating systems

They do. It's sold as corrosion inhibitor.