Cooling System Flush

[mattw1992]

Hello All,

Would like your thoughts on the best process to flush the cooling system. This will be a first for me so more detail is better. Have seen some of the other threads but some suggest only removing the top hose, others recommend, well lots of other stuff. I want the easiest and most effective way to flush the whole system, it hasn't been done in what looks like forever, only purchased this car as a hobby car not too long ago. Appears extremely rusty and looks like it has had some sort of additive put in it.

Thanks in advance.

 

[meady_183]

What I do, not saying it's the best but it's what I've been doing for years:
1. Remove bottom radiator hose at radiator end and allow to drain.
2. Replace hose.
3. Remove radiator cap, put in hose, fill radiator. Leave hose running. Start engine, put heater on full, keep an eye on temps and circulate water for 5 mins after warm.
4. Turn off hose and engine.
5. Allow to cool, repeat step 1.
6. Remove thermostat and housing.
7. Flush water through block from thermostat housing.
8. Flush water through radiator from top hose.
9. Replace thermostat and all hoses.
10. Pour 6 litres of concentrate into radiator. Top up with demineralised water.
11. Remove and clean overflow bottle.
12. Replace over flow bottle and fill with 50:50 mix.
13. Tape coke bottle to radiator filler.
14. Fill coke bottle with demineralised water.
15. Open bleeder screw on top of thermostat housing.
16. Start engine and keep coke bottle topped up, bubbles should rise, and air should come out of bleed screw. Once there is only a stream of coolant coming out of bleeder, tighten.
17. Replace radiator cap. Bring for a drive, check temps.
18. **my extra step** once you return from drive, with car hot, open bleeder screw again and hopefully little to no more air comes out.

 

[codeunknown]

Great and agree....but would add step 19 .... take for a long run with heater on.....and have the heater running when you return home.....and again do the first 18 steps.....reg use the heater now and then to
Make sure the heater water gets a flushing like the block and Rad and hoses...

 

[Husky]

You should also drive around with the heater on prior to starting. And leave it on hot while removing the bottom hose.

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[wortus]

I usually flush out the heater core seperately by removing the hoses from the engine and with the heater tap open flush with a hose. I blow the water out of the heater core before refitting the hoses as this guarantees you will get 6 litres of concentrate in before topping up with water.
I don't bother loosening the bleed screw when it's hot and woudl not recommend that as being needed. I use the coke bottle trick and this should remove the air without having to run the engine.
I also don't bother taking out the thermostat just to fluch the engine. If it's dirty I also think you should remove the overflow bottle and give it a good clean out. A strong solution of laundry powder will loosen up any crud, it will also clean any crud out of the radiator cap.