jeetS

So...two months ago I flushed my entire cooling systen and added Toyota coolant. Three weeks later my headgasket blew and I did it all over again...and more new expensive coolant.

Last week the hose off the back of the timing cover split. I temporarily patched it back together and added a gallon of water from a water cooler(drinking water) as I couldn't find de ionized water anywhere close.

Sooooo....When I put the new hose on should I flush the whole thing AGAIN and add another 30$ worth of Toyota coolant or is that gallon of mineral water not a big deal?

1986 22rte

Duckie

The proper thing to do would be to flush it again, but I personally wouldn't worry about it too much.

RBX

More importantly, make sure your block, head, valve cover, and plenum(intake) are all grounded properly. this will make a big difference to how your engine corrodes due to the differing metals...internally of course.

sb5walker

Depends on how much minerals in the water. The problem with them is that they react with the corrosion inhibitors in the coolant, depleting them to some degree. I think Toyota coolant is a little less affected than Prestone, and a LOT less affected than any Dexcool type (which should never be used in our trucks anyway).

I would probably leave it in there, but I would check the pH of the coolant from time to time. Fresh 50/50 mix of Toyota Coolant and distilled water has a pH of about 7.3. If your coolant goes below 7.0 it has lost its buffering capacity and has turned acidic, and should be replaced immediately. This pH paper has the right range (for Toyota Red coolant) - about 6 to 8, with a resolution of .2: http://cgi.ebay.com/370384991648

85gijunk4x4

the water where im from is so high in iron it cause stuff to rust up pretty quick. id say just do one of those tests where you stick a coolent tester hose in the rad and suck some in by pumping the little ball thingy. if it reads good, it cant be any different then regular coolent imo. but i would still flush it again, its the only right way to go

sb5walker

Those antifreeze testers just tell you what percent of the coolant is ethylene glycol. That's the "antifreeze" chemical, and it is not depleted much by minerals and lasts much longer than the corrosion inhibitor chemicals do. So you could have 3 year old coolant with the corrosion inhibitors long gone, and the coolant pH way down (acidic) and it could be corroding your block and radiator and heater core something fierce, and it might still test okay with an antifreeze tester.

85gijunk4x4

^^ agreed, good point.

jeetS

Thanks!

I just bought those strips.

The trucks came to 7.2. My wifes 05 corolla came to 7.6...I have no idea when or if that has ever been changed...I do know it hasnt been changed in the last three years.

sb5walker

7.2 would be fine for Toyota Red. As mentioned, a 50-50 mix starts out at 7.3, and by two years later when due for changing it will be about 7.0. On the Corolla, if overdue for changing you're playing with fire. One day you'll look in there and see what looks like a Cinnamon Dolce Frappuccino instead of coolant. At pH 7.6, it doesn't have Toyota Red, right? Different coolants have different pH ranges. I've heard for example that the normal range of Prestone Green is 8.5-10.5, but don't know for sure. If that's true, then 7.6 would be very low and overdue for replacement if that's what was in there. I don't know the exact ranges of other coolants, but most modern HOAT type coolants are close to neutral like Toyota Red.

Buck87

I just checked my premixed Prestone and it came out to 8.4 in the bottle.

jeetS

ya its toyota red......if its 7.6 does that mean its fine??

its a 2zz so i definitely wanna take care of it...

sb5walker

Either it's not really Toyota Red, or something's not right. Toyota Red mixed with water should always be 7.3 or below.

Anyway, if it has been in there for three years, change it. I wouldn't run ANY coolant longer than that - even the so-called 5 year extended life coolants. The chemistry of those coolants in the 5th year is messed up. I think it's just a marketing ploy.

sb5walker

I don't think Prestone offers their conventional green antifreeze in a premixed formula, so that means it's either their orange or yellow product.

If it's orange, it's a Dexcool OAT type coolant containing 2-EHA which will corrode the lead solder in the radiator (if not aluminum) and heater core.

If it's yellow, it's marketed as a HOAT "mix with any" antifreeze but it also contains 2-EHA (unlike most other HOATs which use a different, less-discredited organic acid) and will corrode lead solder.

So I wouldn't run it in the vehicle for long, or you'll be replacing rad & heater core.

Buck87

it is green

sb5walker

Look on the back and see if it contains sodium 2-ethyl hexanoate. If so, they've dressed an OAT type coolant in an old conventional antifreeze color.

Buck87

"Contains water, ethylene glycol, diethylene glycol, sodium 2-ethyl hexanoate, sodium neodecanoate"

Buck87

Interesting; so is toyota red the only antifreeze that will should be used?

sb5walker

So that's Dexcool, the OAT coolant that has been involved in all the lawsuits for ruining engines. With green dye. I don't think it's quite as apocalyptic as it has been portrayed, but it has been clearly shown to corrode lead solder - so, probably best to replace it fairly soon. Since the worst problems from Dexcool come from mixing with other coolant types, it will be important to really flush thoroughly, including the heater core and plastic overflow reservoir.

To backflush engine and heater core, drain as much coolant as you can, then pull the thermostat and reattach coolant outlet/upper radiator hose, pull both radiator hoses from the rad, turn the heat lever all the way to hot to open the heater core, then as best you can seal a hose to the upper rad hose and turn hose on medium flow (not full blast). A whole bunch of gunk will come from the lower hose. Flush rad by sealing hose to upper hose attachment and then to the filler opening. Then backflush it (if needed) by removing and inverting rad, and attaching hose to lower outlet. You may want to force some water into the drain valve to clear it, as rust particles and sediment can sometimes foul the valve, causing leaks.

Then, because some liquid will always remain in the heater core and pockets in the block, and because you don't want to mix tap water with coolant, you'll need to do at least one flush with distilled water. Reattach rad and rad hoses, leaving the t-stat out and heater lever all the way to hot. Fill with distilled with front of truck elevated so top of rad is above highest heater hose, then leave rad cap off and run motor for a few minutes, topping off rad with distilled as necessary. Allow to cool to the point where you can hold hand on the head, then drain rad, replace t-stat (with new one from dealer if it has been over 3-4 years), and fill system with 50-50 or 55-45 coolant & distilled water.

Well, it's the best by far. The problem is most modern coolants use organic acid corrosion inhibitors intended for aluminum rads & heater cores, and those acids corrode the lead solder in older vehicles like ours. If conventional green Prestone with sodium silicate and NO 2-EHA or sebacic acid is unavailable, then Toyota Red may be one of the only or very few safe choices. Subaru "Long Life Coolant" P/N SOA868V9210 appears to be the same as Toyota Red, and Zerex G-05 is a possible ok choice too. Despite what the dealer might try to tell you, premixed Toyota Pink uses sebacic acid and is NOT safe for lead solder. More details on coolant issues and quantities needed for 50/50 mix are in this post:
https://www.yotatech.com/forums/f116...nt-faq-192781/

Buck87

Good stuff thanks