Topic

I finally got around to doing my coolant change a few days ago and followed CJJ's how to here http://www.the-t-bar.com/en/forum/22-cjjs-guides/401-coolant-system-how-to-fill-and-bleed

But, I only drained around 7 litres out max - where's my other 3.5 litres? How should I have got that out (if at all)?

I've bled it and have the actual coolant level correct, but it's still under-strength according to my halfords tester. I can't fit any more coolant in without redraiing, but need to increase the anti-freeze level a bit more - I was thinking of removing say half a litre from the coolant tank and topping up with neat OAT instead of the ready mixed stuff I've been using.

Is this a bad idea? Is there a better way to do it?

I think the ready mix stuff is a bit on the weak side, as for the rest not got a clue, you are the spanner girl

Drain a glass full from your expansion tank and stick it in the freezer overnight. If it freezes, it's too weak. Household freezers are usually around the -21C mark.



Don't forget that it's 'anti-boil' as well as 'anti-freeze'.



I've posted this up before. But it's good winter info, so here it is again for those that haven't seen it. -


50/50 works best unless you're in Alaska. Then it's 70/30 coolant and distilled water.

­Cars operate in a wide variety of temperatures, from well below freezing to we­ll over 38C. So whatever fluid is used to cool the engine has to have a very low freezing point, a high boiling point, and it has to have the capacity to hold a lot of heat.

Water is one of the most effective fluids for holding heat, but water freezes at too high a temperature to be used in car engines. The fluid that most cars use is a mixture of water and ethylene glycol (C2H6O2), also known as antifreeze. By adding ethylene glycol to water, the boiling and freezing points are improved significantly.

Fluid - Freezing Point - Boiling Point

Pure Water: 0C - 100C

50/50 mix of C2H6O2/Water: Minus -37C to 106C

70/30 mix of C2H6O2/Water: Minus -55C to 113C

The temperature of the coolant can sometimes reach 121C to 135C. Even with ethylene glycol added, these temperatures would boil the coolant, so something additional must be done to raise its boiling point.

The cooling system uses pressure to further raise the boiling point of the coolant. Just as the boiling temperature of water is higher in a pressure cooker, the boiling temperature of coolant is higher if you pressurize the system. Most cars have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 25C so the coolant can withstand the high temperatures.

Antifreeze also contains additives to resist corrosion.

A quote from Clives' guide here - Coolant system. - How to fill and bleed

MOST of the Fs and all of the TFs specify a 50/50 mix of OAT (Organic Acid Technology) coolant and demineralised water. It comes in many colours but generally looks very bright. Common colours are green, orange and blue. Normal water should not be used as it contains minerals etc that can cause deposits in the engine and radiator (just look in your kettle).

Some older Fs recommend you use ethylene glycol, which is the more traditional coolant. Many people have converted to the better OAT coolant, but if you do, make sure that you thoroughly flush the system first as the two coolants do not mix well.

You can get OAT from most automotive car shops. I got mine from Halfords. You can buy 50/50 ready mixed or concentrated and a seperate container of demineralised water.

A cold system will have a closed off thermostat, trapping a portion of coolant from draining out. Its nothing to be worried about, you'd need to remove the thermostat all together in order to get a full drain.

If its weak just remove some and add neat, although I've never used a tester, so long as its roughly a 50/50 mix you'll be fine.

I didn't measure mine when I drained it, but there was still a lot in the block, which Russell drained when he did the headgasket. He put two 5 litre bottles in when he refilled, bled all points with the bottle full to the top!!!! then syphoned off the "overfill" so about 9.5 litres were used.

Leigh, domestic freezers usually run at around minus 18 degrees C ~ put on fast freeze they may go to - 20 deg C

bryan young wrote: wrote:

Leigh, domestic freezers usually run at around minus 18 degrees C ~ put on fast freeze they may go to - 20 deg C

Our freezer runs at minus 21, and will go to minus 28!
LM: Surely if a bottom block hose and bottom rad hose is removed the block and system will drain: thermostats have a bypass relief aperture to ensure a flow if the stat sticks shut iirc?
Or have I got it wrong again?

I have a good Comark digital thermometer, with a seperate stainless steel probe, will put it inm not dis freezer to see what temp is, I am not disputing your figures. I must say i was surprised to see coolant in the block when Russell lifted the head gasket.

Brrr! Minus 18, 21 or even 28c. The point is it shouldn't freeze in a household freezer if it's the correct 50/50 mix. According to that chart it's around minus 37c before a correct 50/50 mix starts to freeze. It would be around a 70%(water) / 30%(coolant) mix or weaker if it froze. Too weak.

It would be interesting to freeze some of our coolant mixes just to see how a cup full holds up to the extremes of the freezer at home. Even if only to reassure ourselves ready for the next minus 25c spell like we had a couple of years ago.

lidle or aldi had testers recently