Flush cooling system?

[10G]

OK, so I had a shot this today.

I'm confused. I'm only getting around 5-6 litres out of the radiator, the manual says it holds around 13-15 litres.

Firstly, I did a cold flush, just removed the drain plug out of the bottom of the radiator, removed the caps off the radiator and the pressurised rear tank thing. Put an oil pan under it that said it held 16 litres. It got about half filled.

Secondly, replaced both radiator hoses, nothing came out of them. Filled it up with water from the tap, had the heater on flat out & engine running. Filled up radiator and the pressurised tank as needed. Went for a drive, got it up to 87. Got home and drained it. Only about 5-6 litres out again (about half the 10 litre bucket I used).

The water is getting clearer with each flush which is good. Here's a thing. When I undo the radiator cap, the water is hot. When I undo the drain plug underneath, the water is cold, however hot water does eventually come out.

Where's the missing 10 litres?

Am I doing something wrong?

Thanks for any help.

[0-TJ-0]

In the engine? I had this issue and i had to take the thermostat out to drain it properly.

[10G]

Ug. Just been reading that you should never use tap water. I did know that, but I thought it'd be OK for flushing???????

I'm consistantly getting the same amount of water out every time I flush so I hope all that bloody tap water is coming out.

Re thermostat, I was hoping that by getting the engine temp up to normal op temp, 87, the thermostat would be open and all the water would drain through it, maybe that just doesn't happen????

[10G]

I'm letting it drain overnight with the front of the car pointing down, maybe it'll trickle out over night?????

[0-TJ-0]

I reckon as soon as the water drops away from it the thermostat would cool enough for it to close. Dunno mate I'm no expert.

I just used the hose to flush mine, let it drain then filled it with the good stuff after. Might not be ideal but I'm not I'm not paying the premium to flush it with the bottled stuff.

[10G]

I reckon as soon as the water drops away from it the thermostat would cool enough for it to close. Dunno mate I'm no expert.

I just used the hose to flush mine, let it drain then filled it with the good stuff after. Might not be ideal but I'm not I'm not paying the premium to flush it with the bottled stuff.

That all sounds fair enough to me.

So when you removed the thermostat, did you get alot more water out?

[0-TJ-0]

Yeah and it allowed me to stick a hose in one end and flush it through some what. I think there's a drain bung on the block somewhere that will drain a bit more again but I've never used it. Perhaps it might be worth finding that instead?

Edit: On a td42 just for clarity sake.. but on my cruisers in the past I used to have to take the thermostats out to flush them properly as well.

[10G]

Morning after. I reckon about 2-3 litres leaked out overnight. Going to look at removing the thermostat today.

Was reading my Haynes manual this morning. In their 'flushing the cooling system' section, they mention to get the garden hose, stick it in the radiator hose and turn on the tap! So maybe using tap water to flush with is OK????

They also mentioned that the thermo housing has a drain plug and that it can take 30 mins for all the water to drain.

[0-TJ-0]

I need to get one of those manuals..

Yeah have a look and see whats easiest. With the stat out you can push a fair bit of water through to get a good flush though. Just be careful with the bolts. I've read other people having issues with them seizing and snapping?

[Bidja]

Morning after. I reckon about 2-3 litres leaked out overnight. Going to look at removing the thermostat today.

Was reading my Haynes manual this morning. In their 'flushing the cooling system' section, they mention to get the garden hose, stick it in the radiator hose and turn on the tap! So maybe using tap water to flush with is OK????

They also mentioned that the thermo housing has a drain plug and that it can take 30 mins for all the water to drain.

No need to remove thermostat housing(may not be straight fwd), but would enable full flush thru sys.
Remaining water/coolant still in engine block. Drain via eng block plug.
Understand that eng block drain plug is below oil filter and to get to it remove the oil filter drain into tray/bucket. Need to seal drain plug when finished_Read that"threebond grey sag type silicone" works and can pick it up at repco or most other automotive stores.


If using same coolant type you can just drain radiator via bottom plug, then close off and fill with distilled water, warm up and operate full heater to circulate(few minutes) then drain via radiator plug again. Do it a few times. Must say I always only use genuine coolant and have good tank water so that is what I use to do the job. For me, even if changing coolant types this is what I would do anyway.

Had ADRAD radiator joint in ACT do an A/C job for me few yrs ago and got them to do radiator / sys flush, think they just back flushed sys with tap/hose water back thru top heater hose at firewall(heater turned on). Pretty good tap water though.