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Please help: what should I do about green+red=orange mixed coolant?

3K views 8 replies 4 participants last post by  demoder 
#1 · (Edited)
Thanks in advance for any advice--and especially experience. My twin sister and I have (almost) twin Ravs; her Rav is a '99 bought used, and mine is a '00 bought new.
I've done much of the maintenance on my '00, and so it has Toyota red coolant; I'm emphatic about using Toyota fluids (except motor oil). But to my dismay, I'd noticed a little while ago that my twinnie's '99 has green coolant in the overflow reservoir.

She had mentioned to me that her heat wasn't working properly, so today I tried the cheapest fix first---bleeding the coolant system. Well, I used a Lisle funnel, so I had a good look at the circulating coolant, and it wasn't green or red...it was ORANGE.

I have no way of knowing this, but I'm beginning to think that the coolant was mixed (perhaps an incomplete "change"), since the coolant in the overflow is (dirty) green, and the og Toyota would have been red. The mileage on the car suggests to me that the coolant I see is probably the second "change".

What should I do at this point? I plan on doing a full coolant drain and replacing the thermostat in a few weeks when I change her oil during some time of near Thanksgiving time. But what kind of coolant should I replace it with? Do I stay green, or do I try to get back to red?

I'll drain-and-fill with distilled water till its coming out clear. But since the green coolant generally has the corrosion inhibitors, will that cause a surface reaction with Toyota red? Meaning, are the metal surfaces of the system now chemically bonded with something that won't be removed with a flush, and that will react poorly with Toyota red? Should I use a chemical flushing agent?
Also, when I bled the system today, it was so filled with bubbles that it looked like root beer (no joke!). Some bubbles were larger than marbles. But the abundance of little beer-head-like bubbles made me curious if there wasn't some kind of oxidizing reaction happening between the two coolants. I don't know the chemistry, so its just speculation. But the coolant is a strange orangish-brown color, and it was PACKED with bubbles.
Has anyone encountered this problem? (PS--to all those with red coolant, pay the extra $10 and KEEP IT RED and avoid this headache) Thanks for helping me and twinnie!
 
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#2 ·
The orange colour you see is rust. This coming from the cast iron block and clearly shows that the concentration of coolant was inadequate or non existent.

It needs to be drained and possibly flushed. There is some concern that if green and red have been mixed in the past, it can cause sludging and hence the heater not working efficiently. A good flush should cure this and then fill with red.

You say the colour is green in the expansion vessel yet the colour of the coolant is orange? My guess is that the coolant has been drained at some time in the past and then re-filled mostly with water and then topped up with a tiny amount of green anti-freeze/summer coolant. The amount of coolant added to the system has not been enough to prevent corrosion so I doubt there will be any problems by changing to red.

Get that rusty water out asap and hopefully the heater will come back to life.
 
#3 ·
Not necessarily rust. There are aftermarket coolants that are orange and considered universal. But since you don't know the history of the car, its always a good idea to flush all fluids to get a baseline. I wouldnt bother buying the pink toyota coolant. The others are just as good. Flush with distilled water then add straight full strength coolant into the radiator. You are bound to have about a gallon of distilled water in the engine block and adding full strength will mix to 50/50. Get a cheap coolant tester while at the store. It will give you an indication if your coolant is the proper concentration. It may take a while for it to mix fully, be patient.

BTW green and red mixed will give you a nasty brown color. Not orange.
 
#6 ·
Thank you both for your replies!
I have very, very hard and mineralized water, so I do use the (time consuming) method of draining, then filling with distilled water, idling till the thermostat opens, etc, and continue doing this till I get clear water coming out. The last time I did it, it took a long time and about 10 gallons of distilled water, but it does work. It would be good news that a flush would do the trick.
 
#9 ·
Thanks again, I wanted to update this post: I finally had the chance to do the flush on my sister's Rav today, before Thanksgiving dinner. What I drained from the radiator was a very ugly-looking algae-greenish: it really looked like something one would find in a marine setting or a fish tank!
It looked much much less orange once drained and collected in a gallon jug than it did while I was bleeding it in the Lisle funnel. It was pretty bad... but neither myself nor my much-more-experienced-second-opinion source saw any rust, which was a relief!
The thermostat was already suspected to be stuck open, so I just drain/fill/idle/drain through about 7 or 8 gallons of distilled water till it drained out clear. After that, I pulled the thermostat, and it was indeed stuck open: it was clearly stuck, off-axis and appeared totally incapable of closing. I went ahead and put in a new thermostat and gasket, and refilled with Toyota Red. It bleed fine, so hopefully everything will be okay! I hope the other coolant was silicate/borate free, but I don't know (I doubt it).
 
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