How To: Flush & Change the Coolant

I’ve spent the last week talking someone through this most aresache of proceedures and as a result figured it worth documenting for everyones reference

Please add anything constructive, questions or tips from your experience to this thread and I’ll edit and move it to the library later

so how do you change the coolant on the Roadster?

Ok first thing is coolant regardess of what others may say anything is fine as long as it s Ethyl Glycol based and suitable for aluminium engines

You’ll need a lot of it as you will lose a lot bleeding it, cheapest option is Halfords own brand concentrated, get enough to make 20 litres or more.

You will need the car on ramps or stands, I suggest ramps (CLOSE THE RAD DRAIN POINT)

Make sure your heater is on full (no keys in and no engine running)

1. Remove expansion tank cap
2. There is a drain plug for the block, bottom left at the back behind the manifold open it and catch the contents (leave it open)
3. remove all plastics from the front under the nose
4. tied up against the firewall is 2 hoses against a bleed valve
5. take the shorter one and attach to the bleed nipple, masking tape the other end vertically up to the bonnet, open the bleed point
6. take the other hose and attach it to the rad bleed point (drivers side top of rad on the end
7. tape it up verticaly to the bonnet
8. below that bleed point is a plastic thumbscrew open it up but be careful its a crap design and you don’t want it to fall out
9. passenger side of the rad at the bottom is a drain point, open it and catch any coolant that coes out (leave it open)
10. look where the rad feed hoses go under the bonnet and dissapear under the centre of the car. Just after they dissapear there are 2 drain points, ignore them as they will be seized up, just behind them are 2 clips that hold the rubber hoses on, pull those hoses and drain any coolant that comes out, then put them back on.
11. If there is any coolant still in the expansion bottle disconnect the bottle and empty it.
12. when confident no more coolant is coming out close all drain points.

Now to refill

1 mix your coolant
2. fill from the expansion bottle cap slowly pausing to allow any air to come back out,
3. stop filling when the level in the clear hoses at the front is approx the same height as the expansion tank at the rear.
4. close all bleed points
5. start car and idle for 10 mins topping up the expansion tank as needed.
6. kill engine, open bleed points and allow any air to leave the system, topping up at the rear as needed. Massage the coolant pipes where accessable

7. repeat 5 and 6 as neccessary until no more air comes out.

8. shut bleed points replace expansion cap and go for an easy drive (leave plastic out as your not finished yet.)

9. check heater works when driving if not follow heater matrix bleed proceedure below as it’s air locked.

10. return car to ramps, remove expansion cap open bleed points and remove any air that comes out, top up at rear as needed.

if the heater didn’t work follow the below

1. Get an assistant
2. open bleed point on firewall
3. clamp (use a big gclamp) the rad hose that goes between the bleed point and the main rad pipe
4. you need a wet and dry shop vac for this (wicks do one for circa £20 if you don’t have one)
5. seal a hose to both vac and the hose coming from the bleed point.
6. have someone at the rear ensure the expansion tank does not run dry whilst you turn on the Vac
7. you should see the airlock siphon out of the heater matrix up the clear pipe, stop when you are sucking up water

that should do it

repeat various parts as needed if you still have air

keep a close eye on levels and temp over the next few days, expect to have to top up the expansion tanks periodically over the next week.

at all times during the fill proceedure never let the expansion tank run dry.

This documentation in no way replaces the Toyota MR2 Repair Manuals. The purpose of this content is only to provide supplementary information to fellow MR2 enthusiasts. Midship Runabout and its contributing authors will not be held responsible for any injury or damages that may occur as the result of practicing any of the methods or procedures described within this website. Article and photo submissions are property of the contributing author.

You may also like...

1 Response

  1. Dominik says:

    Hi, i know is a bit not about the subject but do you know how much oil do i need for the engine? and gearbox? thanks

Leave a Reply