Cooling System Rust Removal

[ptrain]

Hi Chaps,

I looked at a late 90s corolla at the weekend a friend of mine has just bought. The previous owner, a poor DIY mechanic had heard that water is the same as coolant in a car and the whole coolant thing is a scam to squeeze the little guy .... Anyway I recon the car has been run on tap water for a year or 2. The system is fairly orange. I naively assumed a good flush and some Wynns rad clean would do the job.

I've drained it and flushed it heaps run rad clean through it and flushed some more then topped up with coolant with a bit more concentrate at around 60/40 to try and stop it getting much worse.

I think he'll probably need to do the thermostat and the water pump soon too as its a little slow getting to temp and never quite reaches optimum unless its in traffic. But, there's no point in putting the time and effort into new bits unless we can clear the vast majority of the rust.

Any a advice on how to clear it? I've read numerous people online saying they use a 50/50 water vinegar mix and run it for about 1 week then flush and your good to go. I've also hear of people using CLR for a day or so to do it. I've also heard CLR damages seals and aluminum.

What do you guys do? This must be a relatively common problem.

[sergei]

Yeah, I would personally stay away from rusty engines... Ultimately it leads to BHG.
Most likely what is preventing BHG is thick layer of rust...

All the rust that was "flushed" will accumulate at the bottom of the radiator.
If the radiator is blocked, most of the time garden hose "flush" will not unblock it. Either you will need to get new radiator or old professionally cleaned. Either way there is a high chance of it being blocked later anyway.
In addition the heater core will also be full of rust.
There is a high chance of radiator cap being stuffed, and if that is fixed, high chance of water pump leaking. The coolant also acts as lubricant for water pump seals.

In anyway, when you put coolant make sure it is not cheap green shit with silicate additives. The green shit is for old boat anchor of engines, and not suitable for relatively modern engine. Make sure it says on the bottle Hybrid or Organic Acid Additive (HOAT or OAT), the inorganic salt additive type of coolant will kill your water pump seals and block up aluminium radiator with scale.

[ptrain]

feck!

I've put this stuff into it for him http://www.supercheapauto.co.nz/online-store/products/Calibre-Anti-Freeze-Anti-Boil-Concentrate-1-Litre.aspx?pid=155034#Recommendations

I think the pump is dying I can hear it. Its not loud but doesn't sound to good. And it defo could use a new cap.

[sergei]

Unfortunately "Type A" and "Type B" is very vague specification, and only tells if it does anti-freeze/anti-boil (A) or just corrosion inhibition (B).
So to recap types of coolant:
OAT - is pure organic acid type (best) - new toyota red coolant. Silcate and phosphate free (good for eurotrash and japanese cars).
HOAT - which breaks down in two:
phosphate based HOAT, old toyota red coolant. Silicate free.
silicate based HOAT (Si-OAT), usually used on eurotrash. The silicate content is relatively low, generally phosphate free.
IAT - boat anchor coolant, yank tanks, Lada, Moscvich, Tavria you get the idea


You are after something like this:
OAT
http://www.supercheapauto.co.nz/online- ... mendations

Generally most of the coolants these days are at least HOAT, only cheap green shit that mechanics buy by the barrel are still silicate stuff.
You can mix HOAT with pretty much everything, so if the bottle says compatible with all types, it is most likely HOAT.

With OAT, if you had other type, you will need to completely flush the system.

If you are getting HOAT type make sure it is silicate free (should say on the bottle), if the bottle has whole bunch of European certification but no Japanese, it is most likely wrong type.

It is still much better to run silicate based coolant than just water.