Ford Ka MK1 Coolent flush - query and questions

[dishman]

In the midst of replacing the heater control valve.

But after seeing the state of the coolant, I decided to do a full flush.

It's a bit of a pain on the KA. But I eventually got to the lower rad hose, and drained it.

It takes around 5l and 2.5 litres came out. I also gave the hopper box a good clean and put it back on and filled with some distilled water to begin the first flush.

Now, this it where it gets curious. I filled it between the max/min line and ran the engine.

I squeezed all the hoses and it produced some bubbles. I could feel the pipes getting hotter around the engine but not the rad pipes. I also kept topping up the header tank as bubbles were produced and the level seemed to drop. But at one point the level rose and it was above the max line a bit.

I was keeping the cap off while this was all taking place to let any bubbles escape. Then, I notice the water level rising a bit too much, in a panic I switched off the engine and at the same time the water level suddenly dropped.

My assumption is that the thermostat opened and started feeding water to the radiator, as at this point the radiator pipes started getting warm. So I kept the engine running and then I loosely put the cap back on. After a bit more running I decided to check under the cap and took it off. And the level was rising again, until suddenly it started overflowing.

1) Did I cause the overflow by suddenly taking the cap off while it had built up pressure?

2) What other issues could have caused this that I should check?
I kept adding water as the level fluctuated, but maybe I added too much? At one point it seemed to be above the max line.

3)The rad fan did not come on at all. The pipes to the rad got warm/hot but the rad did not feel hot to touch. But still no fan.

 

[Burnerman]

I really wouldn’t worry too much about this one.....the fact that only half the expected coolant came out means that there will be quite a lot of trapped air in there.
Make sure the heater valve is set to hot, and check for any bleed screws that are in the rubber hoses.
As the thermostat opens there should be a surge of heat through the rad, but that will quickly cool down again until the entire water system reaches around 95 deg C. As there will be air in the cylinder block there will be a belch of air from time to time.
Be patient with it, and it’s a great move to squeeze the hoses as you are doing.
It always seems strange to me that less fluid goes in than seems to come out - even with the water pump removed!
John

 

[Mottie]

Don’t worry too much about the max/min line, it’ll eventually settle down. Put the cap on and run it with the heater on hot but not blowing. It could take 15 minutes or more.

Edit: John beat me to it.

 

[dishman]

I was just worried about the overflow more then anything.

Did I just over fill it or was it because I opened it while it was slightly hot?

 

[Mottie]

I was just worried about the overflow more then anything.

Did I just over fill it or was it because I opened it while it was slightly hot?

Possibly because it was hot but more likely you had an airlock.

 

[dishman]

Ahh, good. I thought it was something along those lines.

I am still trying to work out if the car has a potential overheating problem. Or if it just needs a good service.

So doing this coolant flush first.

Everything has gone smoothly thus far. The system needs a good flush/clean though. I decided to do that with the old heater control valve in situ. Then flush it through as much as possible before putting the new parts on.

I also decided to put in a new thermostat at the same time as the old one must be17 years old now.

The downside with the Ka MK1 is that there are no bleed valves or drain cock. Nor is there any secondary radiator cap to directly access the radiator core.

So it can only be flushed by the coolant tank.

So I am thinking a few flushest with water, then a coolant system cleaner. Then more water. Then new coolant.

 

[Mottie]

So I am thinking a few flushest with water, then a coolant system cleaner.

Trouble with them is that they can sometimes cause leaks. Personally, I’d just drain it, give it a flush through with a hose and the thermostat removed and refill with fresh coolant. Take the bottom hose off and flush it both ways - through the expansion tank and then back up through the rad until it’s running clear. Make sure the expansion tank breather hose is not blocked. If you’re changing the thermostat, get one from a main dealer.

 

[dishman]

Hmm, yeh I was wondering that

Trouble with them is that they can sometimes cause leaks.

That concern was at the back of my mind. So you think it's more of a risk than reward running a cleaner, hmm.

I went for the prestone coolant cleaner which claims to not be too harsh. It's nothing acidic or too caustic I don't think. But, maybe I see how these flushes go before even considering using it.

I will however do as you suggested and remove the top hose to the rad and flush it through with a hosepipe. I was going to skip that.

My only concern is that the system seems full of more crap than I thought. Lots of limescale bits. I was wondering if water would have any impact at all in removing the more caked on crud.

On this ford KA, I think the gasket attaches to the thermostat itself, so I don't think I can run it without the thermostat in situ.

So I assume every time I do a flush I have to ensure it gets up to temp and the thermostat opens.

 

[ReganAndCarter]

Different vehicle, but when it's time to change the coolant I remove the stat and flush through the hole and let it run out the bottom of rad/bottom hose. With the stat in place, it may make flushing less effective as it causes a barrier. Can also back flush up bottom of rad and bottom hose afterwards. After refitting bottom hose, I then get as much new coolant into the stat hole, before refitting stat to lessen airlocks, then refill the rest through header.

Good move using Prestone. It's what I always use and lasts 5 years. Seems to have good corrosion inhibiting properties, as the old coolant that comes out when I change it after 5 years never has any signs of rust in it. Best to get the concentrated Prestone that you mix with water as the ready mixed version works out more expensive.

 

[dishman]

Update:

Flush going well. I emptied the water I filled it with last time after a bit of driving and it came out brown, then decided to do the rad flush with a hose.
I also put the hose in the top hopper and flushed from there, and kept going until the water was coming out clear.

This is the result..



What it should be on the left for reference. Then first flush, second and after a hose through the rad.

I'm still going to do another flush or two after running the engine.

The final thing I need to do is the heater matrix (before putting on the new control valve).

My question is....will this get flow, and therefore get flushed by doing an engine run flush? Or, should I do it the same way I did the main radiator? Disconnect the hoses and do a direct flush.

I have read the heater matrix (on a lot of cars) is quite delicate and I should not use mains pressure to flush it. Rather just gravity feed fresh water in to flush it through.

Thoughts on this?

 

[ReganAndCarter]

The heater matrix will get flow as long as the heater is set to hot. Don't worry about it being delicate. It's designed to handle the high temps and pressures of the cooling system. If you've ever seen anyone removing the rad cap on a hot engine you will get an idea of the high pressures at work. It will handle mains pressure tap water without any problem.

Perhaps they meant the matrix is delicate externally - which it is. You certainly wouldn't want to go jabbing the core/fins with a sharp tool.

 

[Mottie]

Or, should I do it the same way I did the main radiator? Disconnect the hoses and do a direct flush.

Yep.

 

[carmanmemoranda]

Try and do the flush on the matrix in the opposite direction to the normal flow.

The matrix is no more delicate than any other part of the cooling system.

 

[dishman]

The heater matrix will get flow as long as the heater is set to hot. Don't worry about it being delicate.

Ahh yeh, I just rewatched the video. He uses a hose kit to fully connect it to the mains. He just said don't open the tap full.

I assume I'm also ok to flush into the hoses that connect to the heat exchanger.

Also....from what I can see. I'm only ever getting around 2 or 2.5l on a drain. This means there is always at least 2.5 litres left in the car (it takes just over 5l in total).

So...when it comes to a final fill of coolant. I ideally just want to pour in 2.5 litres of concentrate and let it become a 50/50 mix after circulating.
Am I correct with that approach?

 

[dishman]

Further Question:

I've seen the suggestion that after draining I should turn the car over/start for a few seconds to let the pump push/drain any further coolant out.

Any reasons why this would be a bad idea?