Apart from my Focus not actually having a radiator drain plug (see other thread) I disconnected the bottom hose of the radiator instead and let it drain.

I've followed instructions according to plenty of YouTube videos about flushing the coolant.

The issue (if it is) that I'm having is the amount of coolant needed. It states the capacity is 5 litres yet all I have managed to put in is about 2 litres of antifreeze after reaching between the minimum and maximum levels. After letting the engine run, it creeps over the maximum line. I didn't put any water in as there was no space left.

I've referred to the Haynes manual and noticed there's different procedure to filling up the coolant with a 1.6 - see photo. I don't understand which hose they're referring to as I don't know where the ignition is.

That said, when draining the system, it didn't look like 5 litres came out either.

Have I done anything worng? I'm worried that I'm going to damage my engine when I go on the motorway in a couple of days.

EDIT: Acutally, after a bit of more researching, would I be right in saying that when you drain the system, only about half comes out. Therefore, after flushing the system with a garden hose, then de-ionised water, the reamianing liquid left would be de-ionised water so filling the rest up with coolant concentrate makes the ratio about right?

Bit late now but you should have measured the amount that came out.  We have no idea now whether the system is still half full of water or whether it has a massive air lock somewhere.

With the thermostat being on the bottom radiator hose, the engine water jacket will still be mostly full of coolant after removing just the radiator hose, as will the heater matrix inside the car.

Don't think you'll have an ignition coil on that engine, those were replaced by coil packs in the 90's.  The coil pack is the thing with 4 plugs on top that go to the spark plugs.  If you do have an ignition coil, it looks like a small drinks can and is fixed behind the engine on a metal bracket.  The heater hoses are the two close together going into the car in the middle behind the engine.

Thanks very much, I'll have another look. I'm assuming it's near top of the engine at the back rather than underneath?

It's very confusing especially with an MK1.5, the Haynes manual (2001 to 2005) does state 'ignition coil' for 1.6 engines.

Every video I've seen simply shows using a drain plug, flushing and topping the system using the reservoir tank. I thought this job was going to be the simplest, but never is!

What is the correct method for replacing the coolant? I'll keep an eye on the reservoir level and temperature needle over the coming week, and just hope I'm not damaging the engine.

I wish I'd not bothered now, it seemed really clean when I flushed it but I've had the car for just over 10 years and never changed it albeit it's only done about 22,000 miles in that time.

Thanks again, really appreciate it.

Yes, the heater pipes are near the top, should be easy to see.  If it has AC, you'll usually see the two shiny AC pipes going into the car just underneath the heater pipes if that helps locate.

I think there were two different 1.6 petrol engines used in the Mk1, with the 8v Rocam engine used before the 16v Sigma (Zetec) engine.  However I'm not sure the Rocam was still being used in 2001 when the Mk1 was facelifted.

The correct method for replacing is just to pour it in, that's the easy bit!   But then run with the reservoir cap off to purge any air from the system.  Between the waterpump and gravity pulling the coolant down, any air should escape through the highest point, which is generally the reservoir on modern cars.  If there are any higher points, they'll have additional bleed screws.  Literally the same as bleeding central heating radiators in a house.

The rust inhibitor in genuine coolant is only designed to last 10 years, and in aftermarket coolant is often only 5 years, so it does sound like it was due, even if it looks clean enough at the moment.

I can see the AC pipes going into the car, unfortunately apart from that, I'm not sure what I'm looking for.

The big question is why would Haynes instruct 1.4 & 1.6 models to fill the car with coolant via the heater supply hose? Not only that they state '...until coolant emerges from the engine'. Not sure what that means apart from, when coolant comes out of the hose that's being used to fill the engine. Sounds messy and wrong.

I had to top up the reservoir this morning so some parts are getting refilled, or air bubbles are disappearing.

You should remove upper pipe before replenish. When the radiator overflow, then connect the upper pipe. Then press upper pipe 3 or 4 time to remove air. Do the same with the bottom pipe.

On the bottom picture, the heater hoses are directly under the bright green lambda plug on the right hand side.  They're covered in ***** so quite hard to see lol.  Admittedly not where I expected them to be.

Also, you do have a coil pack rather than a separate coil.  If you follow the spark plug leads to the right hand end of the engine, you'll see all 4 leads go into a square block.  That is the coil pack.