How To Replace Engine
Coolant - Antifreeze
Over the weekend I took on the task of a coolant change a friend was
using Steel Seal, and was advised to change his coolant before
introducing Steel Seal to the system and renew the coolant/antifreeze.
Neither my friend or myself had done this before but after ringing around a
few garages and receiving some quotes, one being over £80 and knowing
that the coolant would cost me £25 I told him to forget the garage and
drop the car off. To give you a little background, I’m no mechanic but I
have always done my own repairs, oil changes, filters, spark plugs etc but
never a coolant change so in all honesty I was looking forward to the task.
It seems there have been a few people ask about changing the coolant
and it is often something that need to be done when using Steel Seal or just for maintenance reasons.
He dropped the Vauxhall Corsa off and I set about inspecting the vehicle for a better understanding, I
know that that you can do a complete full system flush but in this instance we just need to drain the
coolant and replace, so here is my guide
To my surprise the job was easier than I had anticipated. This will cover a partial renewal because
with a full system renewal the thermostat needs to be blanked off which needs a few different
procedures with different types of engine.
What is coolant for?
In short antifreeze works inside a vehicles cooling system to prevent liquids in an engine system from
freezing. A common type of antifreeze is “Ethylene Glycol”, Ethylene Glycol is the most common
coolant/antifreeze because of;
A reasonable price tag.
Can be mixed with water in vague ratios.
Does not react chemically with other substances in a cars cooling system.
Has a sufficient boiling point.
Symptoms of poor coolant condition:
The vehicle heats up very quickly
The vehicle overheats
Coolant is discoloured or sludgy
The car takes a long time to cool down even the when fan is engaged
Leaking in the vehicles heater core
Rust building up within the vehicles cooling system
Replacing your car's coolant
What you need:
A bucket or container capable of holding at least 6 litres, preferably wider rather than tall.
Note that you should check your vehicle specs for the exact amount and use a container that
will hold a litre over this amount.
Pair of pipe grips or long reach strong pliers.
5 litres of premixed coolant with antifreeze available from most stores retailing car related
A car Jack. Preferably a trolley jack and two axle stands.
A few paper towels or towels you do not mind having to wash a couple of times.
Access to a garden hose pipe that will reach the engine bay.
Rubber gloves. I ended up with dirty hands, several cuts and scratches. So take care!
Funnel, if you do not have one there’s no need to rush out and buy one.
I cut the bottom off a squash bottle and cleaned thoroughly.
Before proceeding you should also check to see if any hoses are cracked or split.
If they are they will need replacing.
How much will it cost to replace the coolant myself?
All you should need to buy is the coolant which cost me £22.99 and a 70
pence jubilee clip. You don’t need to buy one but if access to the clip on
the pipe is difficult, it makes things a bit easier putting a jubilee clip back
on rather than the spring clip.
This is a saving of £46.31 and took me around and hour to complete
stopping a few times
“Before you begin this procedure make sure you leave the car, not
running and standing for at least an hour, otherwise the engine bay and coolant will be too hot and
“The coolant/antifreeze is extremely toxic to both people and animals; it smells sweet and can also
taste sweet. If ingested it can potentially result in death, you must make sure that any spilt antifreeze
is thoroughly rinsed away with a hose or water. You should transfer your old mixture to a sealed
container a label it accordingly, seek local authorities like a council to arrange for it to be disposed of
correctly. If ingested seek medical attention immediately.”
How to change your coolant
Make sure you have left the vehicle cool.
Position the car in a suitable, level place to avoid the chance of
needing to move the vehicle and in reach of the hose.
Jack the front of the vehicle up enough to easily fit the container(s)
underneath with extra room if you need to look underneath.
Place the car on the axle stands and lower the vehicle down on to them securely.
Open the bonnet and safely using a towel or cloth slowly undo the coolant reservoir/header
This can have high pressure ensure your engine is cool enough and always undo this slowly
listening for a “hissing” to control the release of the pressure.
Keep turning slowly and the “hissing” will fade out allowing you to release the yellow cap.
Place the container/bucket underneath the section of the
radiator where the pipe connects to the radiator.
Using the grips, take a secure hold of the clip on the bottom
left radiator hose and pull it back towards the radiator.
Take a firm hold of the radiator hose and pull away from the
Once you remove the hose there will be a lot of fluid that
flows straight out so make sure you are prepared to catch
this coolant fluid in the container you placed underneath the
Take care to avoid any contact with your skin.
Allow the radiator to drain for at least 5 minutes.
Bring the hose to your vehicle and rise off any coolant that has been spilt.
Here you can by choice use the hose to flush the radiator through.
Remove the top radiator hose and flush the water through until the water appears to run clear
from the bottom.
You can also flush some water through the header tank until clear.
If you do this run some of your new coolant through until you see it come through the bottom
Get your towels or cloths and dry off the radiator connections and replace the radiator hoses.
Secure the hose back on to the pipe and position the clips back on to secure the pipes.
If you have difficulty with this use your Jubilee Clip and secure very well.
Move the container holding the antifreeze/coolant from under the car.
Check there are no more connections to reconnect and there are no objects around the
engine bay or underneath the vehicle.
Position your jacks back under the vehicle and raise up off the axel stands.
Remove the axle stands and lower the car.
Using the funnel or home-made funnel, slowly begin filling the header tank with the new
coolant to the “Kalt/Cold” marking on the tank.
Locate the top left radiator hose, squeeze and release this until you can’t see any air bubbles
coming up in the header tank.
Do not worry about the level dropping, just top up when required.
Repeat this until the header tank stays at the level of “Kalt/Cold” line.
This will help remove the majority of the air in the system.
Replace the header tank cap and tighten.
Start the car up and allow it to run for a few minutes and watch
the coolant level.
After five minutes if there is quite a drop simply stop, open the
cap carefully and top up.
After this allow the car to reach normal running temperature of
about 90 degrees.
Check the tank when operating temperature has been reached
and look for movement of the fluid.
Check for any parts or hoses leaking particularly where you have removed and reconnected
Turn the engine off and allow it to cool for at least 10 minutes then check the level of coolant.
If the level of coolant has dropped simply repeat squeezing the hose carefully and topping up
until the level stabilizes.
If the level of coolant is stable simply tighten the cap, tidy up and close the bonnet.
Move the vehicle away from where you have been working and hose down any spilt
coolant/dirt with lots of water.
Place the coolant in a marked storage container and dispose of correctly.
After you have been driving the vehicle check again and top up if required.
So, you are now complete! You have successfully renewed your coolant, saved yourself some money
and completed a task that most people wouldn’t have a clue about.