240 General: Flushing cooling system

[cheshired5]

Originally Posted by Stephen Edwin

Although I have seen it pointed out that a cooling system is rather different from say a kettle. In a kettle the water is frequently fully replenished, and the water does not get as hot as in a cooling system but is allowed to boil

A correctly functioning cooling system mainly works at lower temperatures than a kettle and will rarely go above 100°C.

[Stephen Edwin]

Originally Posted by cheshired5

A correctly functioning cooling system mainly works at lower temperatures than a kettle and will rarely go above 100°C.

Thank you. I have to think back and I am not sure. I have looked and I see my thermostat is set as 92 degrees. (The thermostat is on a shelf near to me as it happens.) I know that a cooling system is pressurised, so it can run above 100 C without boiling. The old Kenlowe Fan infor used to stress the efficiency gained by running hotter than with an ordinary mechanical fan. But anyway if the temperature is lower that might reinforce my ideas.

Anyway that is the point I think. It does not boil, and the water is not "continuously" replaced.

[Clifford Pope]

It depends what "ions" you are trying to de-ionise. Carbonate ions in a hard water area, perhaps yes. But the main risk is from corrosion of the ironwork producing rust which is then deposited around the system and gradually silts up the radiator and blocks the tubes. Hence the need for a corrosion inhibitor, aka "antifreeze".
You certainly don't want that de-ionised - you want the good ions that neutralise the corrosive ones.

[Stephen Edwin]

Originally Posted by wooble

There's a drain tap on the driver's side of the engine block, towards the rear. It even has a hose barb attached for easy draining, but may be clogged with sediment if you're long overdue a flush.

I flush mine by removing the thermostat and radiator, back flushing the block with a hose on the block drain tap, and flushing the radiator with a hose while it's off the car. I always fill with deionised water as I live in a hard water area and it's cheap peace of mind that I'm not furring up the cooling system.

Thanks again re that drain tap. That has helped me to do a more thorough flush of the cooling system. Before flushing the cooant water ran clear from the tap. I used Radflush and there was quite a discolouration of the coolant that came out afterwards. The additive shifted something.

And yes, the drain tap was well and truly gunged up. I had to take the whole tap out of the engine block to clear the gunge.

That tap will help me in future to collect a lot of the antifreeze mixture for correct disposal when the antifreeze is changed. But after draining through that tap quite a lot of coolant still comes out when I remove the bottom hose. Is there a good way of catching that coolant from the bottom radiator hose?


.

[wooble]

A big bucket and a careful aim :P

[Stephen Edwin]

Thanks Wooble!

[Stephen Edwin]

Catching up on a 2015 thread. Two years later and the coolant change is almost due so I've done it. It's usually warmer in September than November.

I struggled with that engine block drain tap last time. Tried it from underneath but that that wasn't a good angle of approach for me. This time I approached through the engine compartment. That worked much better for me.

Opening the tap is by a 13mm hex. OK with a deep socket on a 4 or 5 inch extension with a long handled ratchet, with a huge drain pan to catch the coolant. 3/8 drive gives good access.

Or, I used a flex head ratchet spanner with a hose to a container. Any 13mm spanner that you can get in to position but it woul be tedious with a non-ratchet spanner. Possibly a crow foot socket would do the job like the spanner with a hose in place.

While opening the tap one can finger feel to be sure the body of the tap is not turning, not coming out of the engine block. Well I could with the spanner. It's a devil to get the body of the tap back in. 19mm deep socket but a lot of patient work by feel first to get the thread to engage.

As for catching coolant, if such as from the bottom hose one cannot use a draining hose, Wooble recommended:

Originally Posted by wooble

A big bucket and a careful aim :P

So it's a 15 litre - big and wide - drain tray with good handles and a spout for me. Cheap enough from eBay.