Thread: radiator

Good question, I've never had to add anything to the coolant in the disco for the year that I've had her. I think coolant's the best thing but can somebody tell us exactly why.

I'm sure it has other properties as well, but essentially it increases the boiling point of the fluid. Water boils at 100 degrees celcius, adding coolant would increase the boiling point. Water temperatures will vary between low 80's to high 90's depending on how hard you're pushing it. Having coolant allows a larger margin before it all starts to boil over.

Some coolants have anti-freeze too, so as well as increasing the boiling point, they decrease the freezing point. Others have anti-corrosives to stop rust.

Never use two differant coolants, as their chemical properties may cancel eachother out. Always flush your system when changing the coolant.

Some coolants are concentrates (add to the water like cordial) and others are straight fills (fill the whole system only with said coolant). Most are green, Penrite make a good Red one, which is for the racing industry - but red looks like rust!!!

By the time you buy good coolant and flush out your radiator, you may as well go to your local radiator place, they should be able to do a quick flush and top up with coolant and to a complimentary pressure test in about 15min for not much more than it would cost you to get the coolant.

Well worth the effort, given that a radiator core for a SII will cost you $400+ 8O

Remember reading somewhere the red coolant is for newer models. Something to do with the radiator being aluminium. Green stuff is better for the copper style so they said.

I just buy the Castrol concentrate in the can at Big W for about $5. Think I put three of them in mine, it's definately green, the usual is two cans to give 30% gycol to water. You can go to 50:50 without causing problems which puts the boil temp past 120ºC. I just reverse flush my system with the garden hose, to make sure my heater is clean I usually remove pipes and flush seperate. I mix coolant a bit thick for beach work, won't boil even working hard in the soft powder in the middle of summer.

Mate has a '84 Hilux and uses that premixed coolant in the system. We were up Walcha way last winter on a fishing trip, his coolant froze, luckily found in the prestart up check. Admittedly it was -8 but mine was still okay. Think it's a very weak concentration in that premixed stuff. It'd be okay if you just trot around town and don't work it too hard.

The first service is probably best given to a radiator specialist as they can get it clean. After that, do it yourself.

All good coolant concentrates will have corrosion inhibitors. They are absolutely essential in alloy engines and are well worth having in cast iron engines to limit rust & scale. Just make sure you buy one recommended for iron/copper/brass cooling system components. Anti-freeze concentrates are about 95% ethylene glycol and the rest corrosion inhibitor.

Mixing these at 2:1 demin water:concentrate (33%) gives full corrosion protecting and good anti-freeze protection if you ever park overnight in sub-zero conditions. Stronger mixes (up to 50%) do give a higher boiling point but glycol actually has less thermal capacity than ordinary water, so it doesn't actually transport heat from the engine as well.

If you never go into sub-zero areas, just a quality inhibitor concentrate (probably about a 200 - 250 ml can?) is fine. If you want anti-freeze protection as well, use something like Castrol Anti-freeze/Anti-boil or Nulon at 33% with demineralised water (buy it in 4L bottles from Coles or Woolies - for use in steam irons).

Pre-mixed coolant is a rip-off in my opinion - you're paying too much for the 67% of it that is just clean water!

Hi all, what leo said pretty much sums it up, in my opinion you would be mad not to put coolant in your system as there are far more benefits than negatives. The coolant not only lowers the freezing point of the water it is mixed with, in all good coolants a rust inhibitor is added to prevent the inside of the water jacket in the engine rusting and causing flaking which will block the fins in your radiator. As for the red and the green coolants, from what i have been told they have identical constitiuants the only difference is the dye used to make it identifiable as coolant, otherwise coolant would be clear. Regardless of where you life coolant is an essential protection agent for your engine, leo is right about the corrosion inhibitor but coolant is just that little bit better, the rust inhibitor can also be added to coolant for extra protection. Matt

The colour is a dye.

So why change from having just green ?

Same idea as those coloured window wiper rubbers you see around, just something to be different ?

I reckon purple would be a wicked colour for coolant if they wanted to add another one.

Originally posted by Ace
As for the red and the green coolants, from what i have been told they have identical constitiuants the only difference is the dye used to make it identifiable as coolant

The red coolant is supposed to be the "long life" coolant rather than the green coolant which is replaced every year or so.
The new Discoveries/Freelanders/RRs run the red coolant but I'm not sure if it's something to do with the aluminium radiators though.

Personally, I can't see the point of running long life coolant in a LR - it always seems to leak from somewhere ops: .