mitsuguy

iTrader: (2)

It has nothing to do with what type of coolant, instead the fact that it is changed before it becomes acidic...

randal

Ok, I see your point. If changed before it becomes acidic is true. However, the cheaper stuff may become acidic much more quickly than the Toyota coolant and since many do not check the composition of the coolant or change it when it should be changed, they just let the fluid become more and more acidic and broken-down. There are also additives in coolant to lubricate and retard corrosion (acidity). The better coolants, like Toyota, tend to have the right additives for the Toyota engine and last for a long time. I am not saying other brands of coolants might not work, it is just that you have to be more vigilant in changing or inspecting them than you might have to be with Toyota coolant.

LeX2K

I tend to disagree. The cheap green coolant allows the system to corrode much faster, I've seen it happen quite a few times. Toyota is extremely picky about their coolant formulation and it shows, even after 10 years on the same coolant there is little to no build or corrosion at all, which of course is way beyond the recommended service life. There are also reports of premature water pump seal failures due to low quality coolant. Toyota coolant IMO is superior and will keep the cooling system spotless.

For the rear cylinder head, crawl under the car and check for coolant seepage, if the head gasket is starting to go you will probably see signs of it, either wet with coolant or there will be dried up traces. It's a tough call but it is best to replace both head gaskets at the same time, but yes the rear bank is a literal pain to deal with.

randal

The spark plugs show the operational "history" of each cylinder. All seem to be fine except that one #6 cylinder. However, looking at the gasket on #2 and #4, I can see it is definitely deformed. In fact, the gasket is just plain worn out. I would have to imagine the rear head is in the same shape although not leaking yet. So, I would love to replace the rear head gasket but still looking for a sane way to gain access.

I have heard that it is possible to rotate (somewhat) the engine from the rear so that it is tilted back toward the front. Maybe take off the exhaust pipe (2 bolts) and an engine mount or two and jack the rear block. Anyone tried that?

BradTank

I think what's important to point out is head gaskets failing does not automatically mean the wrong coolant was used or it wasn't changed often enough.

Replacing head gaskets on a aluminum-head engine after a certain point is usually just a fact of life.
The constant heat cycles effect the aluminum much more than iron heads on cars from the past.

If the coolant acidity was purely to be blamed, the gasket would be uniformly eaten away. Instead, it's in certain spots where there's usually greater pressure or heat.

Replacing a head gasket on a 20 year old car with a few hundred thousand miles that had aluminum heads usually has nothing to do with improper maintenance.

randal

We got the engine back together and running. We only replaced the front head gasket because the rear one looked like such a PITA and was not leaking. So far, all is good! We ended up using a Victor Reintz head gasket from Autozone with new head bolts and the rest of the gaskets being Fel-Pro. We also installed a new water pump (Aisin), timing belt (Kabuki), tensioner and thermostat. Good father/son project. Lots learned by both.

mitsuguy

iTrader: (2)

Definitely Toyota coolant is superior, but only in its service life... The additives simply last longer. Using standard coolant, you just have to use a more frequent change interval, but properly maintained, it won't cause any more problems than the Toyota coolants...

Its kinda like copper vs platinum vs iridium spark plugs. They all do exactly the same thing, with the same results, but copper don't last as long as platinum, which don't last as long as iridium... the difference - when they stop working properly, you notice a loss of performance, when coolant goes bad and beyond its service interval, it slowly eats away at rubber, plastic and even metal...

cooling and transmission fluids are the two most important, overlooked fluids on a car - so long as the trans is shifting right and the engine isn't overheating, most people will NEVER change either of these...

so, yes, Toyota coolant is better, but standard green is just fine so long as you respect its more often change interval...

bosoxr1

I own a 1992 Lexus ES 300 and it is not working because I cracked a head gasket and someone please advise me on any reliable websites as I am looking for a used engine for the 1992 Lexus ES 300?