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

Goudy

The additives in coolant will increase the boiling point (120c or more) and and lower freezing point (around -30 or more for a 50/50 mix) of the water content of the rest of the coolant.
And as already stated, it also has inhibitors to prevent corrosion.

These additives drop out of the mix over time, so you end up with a sticky gunk at the bottom and water floating on top. This obviously encourages corrosion in the system but it also alters the boiling point, lowering it. (and increasing the freezing point)
Which is why the coolant should be changed regularly.

The coolant system is designed to not only cool the engine, but to keep it at it's ideal running temperature, so anything that effects the boiling point in particular can cause problems.
(though in freezing conditions, the freezing point would also become a problem before you even started the engine) 

For a short time, running with nothing but water is generally ok but you've now filled with fluid that boils much sooner than a proper coolant mix and that can effect the pressure inside the system, it's just not really designed to boil it's coolant at a lower temperature.


On the same subject, as you are going to this much trouble to drain/flush and replace the coolant.
Think about replacing the expansion tank cap with a new one as well.

They are designed to hold a certain amount of pressure (usually around 1.2 bar), so have a form of pressure release valve inside them that regulates the pressure inside the coolant system at an ideal level.
 
Just like old style radiator caps of yesteryear, they should be changed periodically as they lose some of that ability over time which tends to cause leaks, collapsed hoses and over heating.

They aren't expensive, probably less than a tenner and the job of screwing a new one on isn't hard.

It's worth going the extra step, you made sure the coolant is good so boils/freezes at the right temperatures, so now make sure the system can run at the ideal pressure.

ElefantEd

Grumpy_chap said:

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.

Water is known as the universal solvent because it dissolves a great many things (though not oils and similar organic molecules).

I agree that deionised water would tend to leach ion out of surfaces it comes into contact with, but of course it therefore rapidly becomes un-deionised again. Not all surfaces would be attacked though, it will depend on the metal eg stainless steel has a coating of Chromium Oxide which is insoluble.

I suppose that deionised water exposed to air would absorb CO2 to make a weakly acidic solution (though this maybe wouldn't really apply inside a sealed system anyway). This might corrode some metals more than tap water would.

Saying that deionised water is very corrosive is overstating things. It's not like the blood of an Alien, melting holes in anything it comes across. Over time it will leach ions from (some) surfaces, but at some point the concentration of ions will reach equilibrium. And for some surfaces tap water, being full of chloride ions, may well be more aggressive than deionised water.

facade

Water is known as the universal solvent because it dissolves a great many things (though not oils and similar organic molecules).

I agree that deionised water would tend to leach ion out of surfaces it comes into contact with, but of course it therefore rapidly becomes un-deionised again. Not all surfaces would be attacked though, it will depend on the metal eg stainless steel has a coating of Chromium Oxide which is insoluble.

I suppose that deionised water exposed to air would absorb CO2 to make a weakly acidic solution (though this maybe wouldn't really apply inside a sealed system anyway). This might corrode some metals more than tap water would.

Saying that deionised water is very corrosive is overstating things. It's not like the blood of an Alien, melting holes in anything it comes across. Over time it will leach ions from (some) surfaces, but at some point the concentration of ions will reach equilibrium.

I think the "corrosion" is overstated due to leaks appearing when some of the calcium deposits, and other corrosion products, that were previously blocking holes pass into solution. A good reason never to let cooling system flushing products go through the heater on an older car....

And for some surfaces tap water, being full of chloride ions, may well be more aggressive than deionised water.

e.g. stainless steel.

Never try and clean/bleach/sterilise  a stainless steel vacuum flask with hypo-chlorite (Milton) it will corrode and eat away any micro-pits to breach the vacuum seal. It also etches the surface so that tannin can adhere better.- use a steradent tablet instead

m0bov

Using De ionised water in screen wash when making up concentrate is good to prevent blocked jets and smells. Saying its corrosive is totally false.

seatbeltnoob

born_again said:

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.

every car is different.

Removing the rad hoses and thermostate are as good as useless in this car. Because the radiator drain valve takes all the fluid out of these areas.  the bottom rad hose connects about 2 inches higher from the bottom. The drain valuve is smack bang on the lowest part of the radiator. Based on past experience when thermostat was replaced, if you drain the coolant from the radiator drain valuve, the thermostat removal will be bone dry.

The fluid is trapped in the heater matrix and oil cooler which is trapped behind the exhaust manifold. To take off these hoses there is considerable amount of work. A lot of electronics in the way, components like AC compresser, alternator underneath, wiring harnesses and other compononets in the way so you can't get access to the hose clips etc.

it's all a lot of work and quite bothersome You still wouldn't be able to get all the water out unless you get into the heater matrix and disconect it, I'm sure there is abit of u-bend type situation in the engine itself where you can't get water out unless you phstically tip the engine on its side.

I decided to do 4 drain and fills and on the last round the water is pretty clear so I think that's acceptable.

engine has 5litre coolant (revised down from OP after further research). drain takes out 2.5L each time so 50%is removed.

first drain

100% / 2 = 50%

2nd drain

50% / 2 = 25%

3rd drain

25% / 2 = 12.5%

4th drain

12.5% / 2 = 6.25% of original coolant left

That is an acceptable method as the car was driven well between drains and the thermostat opened up to circulated the fluid all around.

Ganga

seatbeltnoob said:

born_again said:

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.

every car is different.

Removing the rad hoses and thermostate are as good as useless in this car. Because the radiator drain valve takes all the fluid out of these areas.  the bottom rad hose connects about 2 inches higher from the bottom. The drain valuve is smack bang on the lowest part of the radiator. Based on past experience when thermostat was replaced, if you drain the coolant from the radiator drain valuve, the thermostat removal will be bone dry.

The fluid is trapped in the heater matrix and oil cooler which is trapped behind the exhaust manifold. To take off these hoses there is considerable amount of work. A lot of electronics in the way, components like AC compresser, alternator underneath, wiring harnesses and other compononets in the way so you can't get access to the hose clips etc.

it's all a lot of work and quite bothersome You still wouldn't be able to get all the water out unless you get into the heater matrix and disconect it, I'm sure there is abit of u-bend type situation in the engine itself where you can't get water out unless you phstically tip the engine on its side.

I decided to do 4 drain and fills and on the last round the water is pretty clear so I think that's acceptable.

engine has 5litre coolant (revised down from OP after further research). drain takes out 2.5L each time so 50%is removed.

first drain

100% / 2 = 50%

2nd drain

50% / 2 = 25%

3rd drain

25% / 2 = 12.5%

4th drain

12.5% / 2 = 6.25% of original coolant left

That is an acceptable method as the car was driven well between drains and the thermostat opened up to circulated the fluid all around.

Well done ,if you are bothered you can buy a cheap A/F tester ,not 100 accurate but will give you a good idea of your A/F mix . 

born_again

seatbeltnoob said:

born_again said:

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.

every car is different.

Removing the rad hoses and thermostate are as good as useless in this car. Because the radiator drain valve takes all the fluid out of these areas.  the bottom rad hose connects about 2 inches higher from the bottom. The drain valuve is smack bang on the lowest part of the radiator. Based on past experience when thermostat was replaced, if you drain the coolant from the radiator drain valuve, the thermostat removal will be bone dry.

The fluid is trapped in the heater matrix and oil cooler which is trapped behind the exhaust manifold. To take off these hoses there is considerable amount of work. A lot of electronics in the way, components like AC compresser, alternator underneath, wiring harnesses and other compononets in the way so you can't get access to the hose clips etc.

it's all a lot of work and quite bothersome You still wouldn't be able to get all the water out unless you get into the heater matrix and disconect it, I'm sure there is abit of u-bend type situation in the engine itself where you can't get water out unless you phstically tip the engine on its side.

I decided to do 4 drain and fills and on the last round the water is pretty clear so I think that's acceptable.

engine has 5litre coolant (revised down from OP after further research). drain takes out 2.5L each time so 50%is removed.

first drain

100% / 2 = 50%

2nd drain

50% / 2 = 25%

3rd drain

25% / 2 = 12.5%

4th drain

12.5% / 2 = 6.25% of original coolant left

That is an acceptable method as the car was driven well between drains and the thermostat opened up to circulated the fluid all around.

The idea is not to drain it out, but flush the old coolant & and sludge in the system out. Which is why you do it in reverse...
Think of it like a power flush on a home heating system 👍

Using hose method you get 100% out of the engine & heater system.
Bit in rad, you can use drain plug to get out. Could even block lower pipe & flush clean water through rad from top hose. Again gets 100% out.

This is a very old & well tried system 👍

seatbeltnoob

born_again said:

seatbeltnoob said:

born_again said:

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.

every car is different.

Removing the rad hoses and thermostate are as good as useless in this car. Because the radiator drain valve takes all the fluid out of these areas.  the bottom rad hose connects about 2 inches higher from the bottom. The drain valuve is smack bang on the lowest part of the radiator. Based on past experience when thermostat was replaced, if you drain the coolant from the radiator drain valuve, the thermostat removal will be bone dry.

The fluid is trapped in the heater matrix and oil cooler which is trapped behind the exhaust manifold. To take off these hoses there is considerable amount of work. A lot of electronics in the way, components like AC compresser, alternator underneath, wiring harnesses and other compononets in the way so you can't get access to the hose clips etc.

it's all a lot of work and quite bothersome You still wouldn't be able to get all the water out unless you get into the heater matrix and disconect it, I'm sure there is abit of u-bend type situation in the engine itself where you can't get water out unless you phstically tip the engine on its side.

I decided to do 4 drain and fills and on the last round the water is pretty clear so I think that's acceptable.

engine has 5litre coolant (revised down from OP after further research). drain takes out 2.5L each time so 50%is removed.

first drain

100% / 2 = 50%

2nd drain

50% / 2 = 25%

3rd drain

25% / 2 = 12.5%

4th drain

12.5% / 2 = 6.25% of original coolant left

That is an acceptable method as the car was driven well between drains and the thermostat opened up to circulated the fluid all around.

The idea is not to drain it out, but flush the old coolant & and sludge in the system out. Which is why you do it in reverse...
Think of it like a power flush on a home heating system 👍

Using hose method you get 100% out of the engine & heater system.
Bit in rad, you can use drain plug to get out. Could even block lower pipe & flush clean water through rad from top hose. Again gets 100% out.

This is a very old & well tried system 👍

I live in a flat (upstairs) with no access to running water [to the car]

Secondly I'm not sure how it will get 100% of it out when you're using tap water and introducing chlorines and minerals from the tap water into the system. Secondly the thermostat will never open because it will never get to temperature as you're introducing cold water into the system constantly. So you have a dead zone blocked off by the thermostat in the system.

Just like engine oil, you're never going to get 100% of it out unless you strip the system and I don't think you need to get 100% of it out for it to be effective.

Arunmor

seatbeltnoob said:

I live in a flat (upstairs) with no access to running water.

Eek! How do you live with no running water?