I am wishing to flush my coolant if you can call it that. Had my cooling system flushed twice in one year. They used castrol coolant and after four and a half months both times it went rusty. I am wishing to do this one myself and i dont know where to start. It is on an Au V8. All help would be much appreciated. Also is Nulon coolant good or is there better out there. Thanks in advance.

sounds like the engine block and rad need a high pressure flush!

brown coolant can also be from mixing different brands of coolant

the best way to do the flush is to undo the over flow bottle
make sure engine is COLD!
turn on the heater tap
remove the fans ( 2 10mm bolts and a electrical clip )
remove bottom rad hose

remove the thermostat housing

let it all drain out
and stick a hose in the over flow bottle and rinse
also do the same to the bottom rad hose and themostat housing
stick the hose in the bottom rad hose spout and reverse flush the rad to help

i usally undo most of the hose and stick the water hose in there and flush


get some redline water wetter and 15 litrs of distelled water
3-4 yrs i have had this in my car and still i cant get it above half way

Isn't there a drain valve at the bottom of the radiator?

Thanks guys. I am planning to do the flush next week on monday or tuesday. I will have a crack at it a get back to you when it is completed should upload an update around tuesday night or wednesday morning wish me luck. Once again thanks

Yeah but it doesn't get much out, Frank's way is a better way of doing it and he is right about mixing coolants can cause this problem, this is not uncommon and just draining using the radiator will not get all the old coolant out.

Also I would recommend taking off the heater hoses and flushing the heater separately and reverse flushing via the heater hoses as well, you would be surprised how well coolant and crap can get trapped even through the heater tap was open.
This doesn't cost you anything other than your "time", which is why many coolant flushes are not done properly in a workshop, time cost money and sometimes this can blow out the time in a fix price service, think about how many customers whine about any extra costs above quoted service cost.

Also put a TEFBA radiator filter in your top radiator hose. A lot of people laugh at the idea but they certainly catch heaps of dirt and crap before it gets into your radiator and lodges.

Once again thanks guys. All your advice is much appreciated. Thanks for the heads up on reverse flushing the heater hoses, and also the filter suggestion. Still planning to do the work next monday os tuesday. I will hopefully post a completed report on tuesday night or wednesday morning thanks again guys.

I would agree with this, I fitted a new radiator to a new engine, it was flushed first but not good enough, it partially blocked the radiator the first time the engine got a hard time, which was straight away

Anyone got an idea what the radiator filter is worth now?

Hi everyone. Did the flush today it was like a brown jelly type sludge. All was going well until... I cracked the thermostat housing! The thermostat wasn't sitting in the housing properly and this caused the housing to leak from behind I thought that I didn't tighten it up properly and CLINK craked the housing. I was very upset at first as I thought that I snapped the bolt. Replaced the housing with a new one Ford wanted
$178 for a genuine part however the guy at the spare parts shop said that the housing was identical to another housing of something different (he wouldn't tell me which make and model). This only cost me $85. Under advice from Mr Spares he heavily suggested that i run it without coolant for a day or 2 to check for leeks, and if all is well then just to drop the bottom hose and fill with coolant. I opted for Nulon as they told me this is best for my car. Hope their right. Also tried to get my hands on a TEFBA Filter you can only get them on EBAY, and my wife is already UNHAPPY because i trashed the top radiator hose and had to buy a new one Genuine Only Part! Between the hose and the housing The Wife is spewing. I asked wife to give the throttle a push so she redlines and hits the limiter. I am worried about engine damage as my beast now has a knock during idle and under reasonably hard acceleration. Hoping it is nothing major but just a dose of bad fuel.
Planning to check for leaks and reflush again on the weekend. Hope it goes better this time round.

Once again I thank You all for you contributions and advice THANK YOU.
It was much appreciated. Keep in touch.