This is the worst problem that I have ever seen from 4Runner (actually from any of the car that I have ever serviced/owned).

The tranny oil cooler line in the bottom of radiator seem actually corroded and cracked and spilled all (most of) tranny oil and coolant on the drive-way.

Closely examining, it looks like the oil seems seeping into the radiator or/and coolant probably mixed with tranny oil through oil hose... Immediately ran to the toyota dealer to pick up the radiator (how lucky, they have it in stock) and will do the tranny flush and radiator flush today. It is 2000 4Runner Limited Auto with 80k miles.

Now I wonder,

1. Is this common?
2. How come this happen? the underbody plate are pretty sturdy and protecting pretty well. Moreover, there are no visual signs of damage or scraping or anything.
3. I believe "flushing tranny" in dealer should be pretty safe. Right?

I wonder, I wonder...

Hope things go well today.

One positive side is, it looks like such damage has "probably" been slowly progressing, which means, tranny and cooling system may have been running under "compromised state" with oil/coolant mixed for quite some time. But the runner has been running flawlessly.... hope there is no (or minimal) damage to the car.....

 

how many miles on your rig? Flushing shouldnt be a problem... Back in April I got stuck in a small pond/river, and had to leave my rig overnight, the thing sat in windshield deep water for over 14 hrs, when I pulled her out... I drove it home, and imediately began flushing... my tranny had 270k at the time, and still runs, I am starting to have issues now tho.... my situation was a bit more extreme than yours, tho. Just make sure you get at least 20 qts fluid to flush with, the cheap stuff is fine for that... once u have flushed all the water out, drive a few miles, making sure to use all gears, the return, and re-flush with quality fluid. You should be fine, my tranny has been water logged several times, and with almost 300k, is just now running into issues.
goodluck... hope you can save your tranny.....its a pita to swap.

 

[QUOTE=Jin_Chris;50907543]This is the worst problem that I have ever seen from 4Runner (actually from any of the car that I have ever serviced/owned).

The tranny oil cooler line in the bottom of radiator seem actually corroded and cracked and spilled all (most of) tranny oil and coolant on the drive-way.

2. How come this happen? the underbody plate are pretty sturdy and protecting pretty well. Moreover, there are no visual signs of damage or scraping or anything.QUOTE]

The lines inside the rad corrode, allowing fluids to mix.... happens all the time, and unless u check fluids on a daily basis... most people will never know till its too late.

 

After I replaced my radiator (not for the same reason as you did) I just by-passed the tranny cooler, to an aftermarket one. I do not need to deal with the dreaded mixing of the fluids. Its the wifes rig, so I know by the time I checked the fluids it would be too late. Not going to risk $3,000 on a rebuilt tranny over that!

 

There is seemingly more and more of this happening...

It is happening more so on the 99+ 4runners...The earlier ones seem to partially clog radiators and have overheating issues.

Toyotas are not known for this happening.I believe it could be from a combination of two things.Material change in the radiator trans cooler when they were built being more senitive to corrosion,even though the replacement part #'s for the 4cyl,v6 4runner and tacoma are the same?Why are the 4cyl,and v6 tacoma's not having problems like the v6 4runners?I have not heard of the replacement radiators having this problem.So was there a manufacturing problem?who knows?

The other posibility is the coolant becoming more corrosive from prolonged changing/flushing...There are a lot of differant metal componants in contact with the cooling system,cast iron,aluminum,steel,ect...rise in Ph level the coolant system becomes a small battery,moving cast to steel,steel to cast,ect.Hence the pitting.

On my 97' I bypassed the cooler in the radiator completely with a aftermarket oversized one,and sealed off the radiator trans ports.

I'll take my chances with the trans overheating, VS. coolant and trans mixing.I travel out of state often so If it corroded and mixed the trans would smoke way before I caught it,and being stranded in BFE is not fun.

It's been about 6k miles since the bypass,no problems from trans and fluid is nice and red.

 

Yeah gotta agree with 97ltd4x4. Neglected coolant becomes corrosive. We get ford trucks and suvs all the time for leaking heater cores. Its always due to neglected coolant changes and the coolant ate a hole in the core.

 

Thank you for your reply.

The car was dropped off in this morning in local Toyota dealer. The coolant flush and tranny flush were roughly $260+a (tax etc), yaik! Right! it is rather overcharging. But I do not have time to DIY at this point.

By the way, interesting are, it has currenly about "only" 80k miles. Moreover, not even a year ago, the tranny fluid & coolant were all replaced along with t-belt, waterpump, spark-plug (complete-tune-up) at local mechanic (Not a dealer). I really wonder why such corrosion was not really detected at that time, who knows? if the mechanic actually damaged the part....

Anyway, well-clean-up 4runner will be back on the road by this afternoon.

By the way, I have "also" 97 4Runner SR5 Auto at 130k miles" right now, which is running pretty nice although it started showing some age. What would be the proper interval of coolant change to avoid such chaotic situation? The coolant & tranny were replaced about 2~3 year ago at 90k miles. I usually change coolant 30~50k miles interval...

Regards,

 

3rd the neglected coolant change.

if you change the timing belt at the recommended service intervals, [which basically includes all belts, since you are digging in there] this also means
new coolant, because the hoses have to come off


so, there is in fact, no problem. if all the owners follow the manual
it just can't happen from corrosion.

 

Oh no...not a another one. Here's some other people with the same problem:

https://www.yotatech.com/forums/f2/r...-fluid-116812/

https://www.yotatech.com/forums/f2/d...diator-134072/

https://www.yotatech.com/forums/f2/d...-cause-127401/

https://www.yotatech.com/forums/f2/t...-burst-126886/

And related:

https://www.yotatech.com/forums/f2/b...cooler-126953/

https://www.yotatech.com/forums/f2/m...ed-now-127715/

 

Exactly what I was thinking. I have 155,000 km on mine and I'm seriously thinkng about replacing my rad before it goes.

 

This really makes one wonder about using a cheap aftermarket radiator though. I'd still bypass the radiator and use an aftermarket air to oil cooler with a built-in bypass for cold weather like this:
http://www.importperformancetrans.com/coolers.shtml

 

+1 to mt_goat

I personally "trust" the quality of Denso radiator. Compared to many other aftermarket brand, their build quality seems best although I yet don't get why this problem happens other than "neglected coolant".

Therefore, instead of replacing radiator, I would rather regularly service coolant and install "independent" tranny oil cooler. In that way, at least, "mixture" will never happen.

Now, question would be, which model 4452 or 4454? 4588 seems a bit too thick...

 

I'm using the 4454 on a stand alone basis with very good results, but I have it right up front with good natual air flow and also have fan assisted air flow.

 

this can also occur from time.

coolant flow will eventually wear through any piping or hoses especially at the bends. but toyota cooling parts are 'lifetime' for whatever that means. I once wanted a dealer to change all my hoses and the service dept stopped me and said you don't need them, but I told them yeah but i want them and they said I just don't need them save my money.

nice to have a dealer service dept that will fix what needs to be fixed, and prevent me from throwing too much money at them. not that i am loaded but I ain't poor either. they kept me from wasting money on more than one occasion

 

I was able to mount a tru-cool 4589 between the grill and condener,its a little tight because its so thick and the hoses had to be double clamped because of slight loosenes between the fittings and hose diameter I was using,I didn't want to use a coupler,more chances for leaks.It seems really heavy duty,cheap too.

http://www.transmissioncoolers.us/Me...roduct_Count=1

 

My 2000 sr5 4 runner auto with only 100900 miles just spouted the pink shake.
The gas station I rolled into replaced radiator & hoses, thermostat and flushed a chemical cleaner and 16 quarts of DexIII for near $900.
Preventive radiator replacement or adding another cooler is a good idea.
P.S. I've learned a lot here & needed to share finally
VinNY1

 

hmm, more and more common.. Well, we could hope for a recall maybe..even a TSB?