2014 Ford Fiesta ST (MK7.5) Part 2: Changing the Coolant 👨‍🔧🚘

Welcome to Part 2 of my Fiesta ST repair series. In today's video--or rather videos, as I'm uploading Part 3 immediately after this one as they're related--I'm going to be demonstrating how to change the coolant. The methods here apply to a broad number of cars, so just follow the principle of removing radiator or expansion tank cap, draining from the hose (do not use plastic "petcock" drain taps on cars over 5 years old as they easily break), refitting hose, refilling coolant, then bleeding the system to avoid air locks.
The ST's service schedule states that their purple Super Plus antifreeze should last 10 years or 100,000 miles. As sceptical as I am, this ST has been leaking coolant for sometime and has been topped up with red, so I'll be replacing it for the same. I also mention an idea for an upcoming video to test if using tap, distilled or de-ionised water can cause any issues with the coolant internals. Please SUBSCRIBE as it might be one you don't want to miss!
Check out the following video in this series where I replace the header/expansion tank, as well as replace the faulty coolant bypass valve, a very common failing point on this engine:
Thanks for watching!

[@ja8507]

Chemistry Graduate here, both distilled and deionised are very pure and have pretty much all dissolved minerals removed. Deionised may be more 'pure' and it is very good at dissolving things (not really metals on its own though) due to it's lack of dissolved solids, however both should be fine to use in your cooling system. Most Premium and OEM coolant/ antifreeze contains corrosion inhibitors or anti corrosion properties to stop degradation of your cooling system for around 10 years (on average). DI water is bad for humans as it sucks out all of our minerals, but you want the exact opposite in your cooling system so you don't get mineral deposits. Hope this helps.

[@boilerhousegarage]

Thanks very much for taking the time to explain that. I looked a little further into the claim that deionised (nearly completely pure H20) has a force that can "suck ions" from other materials, thus effectively being corrosive, or at least sharing the effect. However it turns out to be a myth that stemmed from old pipe work disintegrating when used with it, as the calcium from the previous "hard" water broke down into the softer and it was effectively holding the pipes together. Despite that, some scientific and laboratory equipment still warns against deionised and says to use distilled. I'm currently running a long term test of the different water types (with and without antifreeze) using sections of a heater matrix (simulating a radiator) and a couple of other materials. I'll be doing a video on it once I have some results.

[@SandroTsitsishvili]

can i use normal water or distilled water to clean the tank before filling new coolant?

[@boilerhousegarage]

Just the expansion tank would be fine with normal water, or flush everything with it and just make sure the final flush is with distilled. The issue I found with tap water (despite most people and almost all garages using it) is the limescale build up after several heat cycles. If you're in a "soft water" area or have water softening stuff at home then you won't need distilled water anyway.

[@armed_but_blind2768]

I did a system flush and there is some white bubbles left in the expansion tank I think I may still have some coolant cleaner left in the system. Should I just flush it again or is this normal after a flush

[@boilerhousegarage]

That's likely residue from a detergent which I think will be absolutely fine, as you can never quite clear the system with anything you've added to it--which becomes a pain with those "waterless coolants" like Evanscool--so the flush/cleaner won't harm anything in a small amount like that. Personally, I only ever flush using a couple of run throughs of water until the brown mess or darkened liquid you can get in old coolant clears, then perhaps do another change after a year (rather than 3-5 years) if the system was particularly dirty or clogged. I'm doing a similar thing with the oil on this FiST, as it wasn't changed for so long, I've done two oil changes close together as if it were a "flushing" oil, then another change at 3 months, then 6 months, rather than using an oil additive to flush.

[@armed_but_blind2768]

@@boilerhousegarage thanks for your quick reply. I may flush with water again to be sure I think it took about 4 litres of new coolant and then got some foamy bubbles in the expansion tank although the coolant still looks pink and I did a good few pass throughs with water to flush it after the cleaning cycle.

[@boilerhousegarage]

You could try just draining the expansion tank, as the aeriated bubbles would probably head there and get trapped, save draining the whole system again. I honestly don't think there'll be any adverse effects from having it in the system as there's no way the cleaner will be marketed if a small amount left would cause problems.

[@armed_but_blind2768]

@@boilerhousegarage thank you you have eased my anxiety 😂