Right before toss it to local dumster, I was just curious to see the inside.
Yes! it is the well known spot of problem for coolant + tranny oil mixture happening, that many seems experiencing thesedays 96 and after 4Runners.

By the way, I didn't have any overheating, coolant bursting problem at all. I just replaced radiator to be preventative when I just did t-belt/waterpump etc service at 140k miles for this 97 4R SR5 Auto. Again, it didn't have any apparent sign. Then, I opened up this OEM original 12 years old radiator to find if there is any sign of potential issue.... here we go.

The first picture. As you can see, there is no apparent sign or damage anything. Nice and clean even inside of radiator... little reddish residue from toyota coolant.



Then, looking at the holes where tranny cooler lines are attached, there is pinkish/whitish powery residue forming around the area FROM INSIDE....



Ok! now, here we go, look at this cooler conneting area... that is totally messed-up. The oring or rubber gasket thing is totally damaged and does not even funtioning as a gasket. On top of that, it is not just rubber gasket having problem. look at the next picture









Can you see that the tip of the cooler connetion started being corroded and actually looses its own dimension, meaning it does not retain its origital tight surface due to corrosion. I suspect this is the major problem area. Once oring/gasket is messed up, if this tip becomes corroded and damaged, the coolant will start leaking out through such gap at lower tank. If any body experienced sudden rupture of lower tank and gushing out coolant, that means this area was certainly damaged.



On top of that, the major reason of "bursting cooler line connection" is (I believe), it is push-fit connection. Look at this picture. This small little oring is pretty much all it has in terms of "separating tranny oil from coolant". Once the cooler connection area becomes corroded with deteriorated gasket, it loses its sealing and friction that can hold that L shaped cooler connector pipe. Then, this oring is the last one holding the L cooler connector pipe in the cooler itself. If any vibration is caused in that area, then, bang!, all of your coolant and tranny oil will gush out of lower tank...




Again, I didn't have any sign of this problem. I wouldn't even know if I didn't open and see this thinig from inside...
I am glad I just replaced my radiator BEFORE any catastrophic thing happens.

Then, now the question is how to prevent this thing from happening?...
Get a new rad!

I don't think regular coolant change will prevent 100%. How do I know? because I did pretty decent maintenance myself. I changed coolanat at 50k, 65k, 90k, then, 140k. Yes!, not at exactly 30k interval. But I tried perform coolant service roughtly at 3 years interval... Then, was such corrosion caused by not replacing coolant at exact 30k interval? haha.. I doubt it. I wish the OEM rad to be designed a little different/more conservative way... especially the area where coolant and oil can be mixed up....

 

I demolished mine with a baseball bat and ran it over, and over...and over...

 

That is why I replaced my radiator and isolated the transmission from the radiator by installing a B&M cooler transmission cooler and spin on filter. I like strawberry milkshakes in my cup holder but not in my transmission. Plus my transmission run ALLOT cooler, before it would run about 175 on the highway and could get up in the 230 range in the city. Now it runs around 110-120 on the highway and in really bad stop and go traffic or hard acceleration it never gets over 190F.

 

Finally, someone has posted pictures showing the likely failure mechanism for the strawberry milkshake. Tranny cooler for me in the no so distant future.

 

Seeing those pics makes me want to change my radiator, change the coolant, and get a tranny cooler.

 

ouch i wont have that problem

 

Any suggestions on a good tranny cooler? I'm still on my stock radiator at 140k and this thing has to last me for a good couple years

 

This post is a service to all us 3rd gen 4Runner owners. Installing a tranny cooler on my 98 and isolating the tranny fluid from the radiator just went from 'someday' to next week. Thanks for the photos.

 

Great thread man , even though I dont have a 95 + tacoma or runner , anybody that does should change this out ASAP.

 

very helpful for the visually-imagination look impaired- like me! Appreciate the wealth of photos.

Very glad to have the manny tranny for a 3rd gen. FogRunner sure seems to have the right solution, anything else factory wise is just looking to happen again over time.

 

Thanks for the good info and pics Thanks Much respect

 

it is a good thing you replaced it when you did. Mine was unlucky enough to become a milkshake. When i tried to disconnect the trans lines from the radiator, they fell off. Surprising from a vehicle that comes from japan

 

Ah, I must do this asap. I'm new to 4Runners, and I'm sure I could find info here on YotaTech concerning the best tranny cooler options, and the best aftermarket radiotor options.....but since this is already such a great thread, why not add that info to it?


Jin_Chris, what products did you use on your 4runner when you upgraded? Much thanks!

 

I went with a B&M cooler #70264 its 11"x7" and runs about $70. It doesn't feel flimsy like the Hayden coolers its very well built. Even in Houston,Tx summer heat with stop and go traffic it never gets hot. And over the summer I got to torture test it in Colorado.

I drove up Pikes Peak with 4 adults in the car and 500LB of stuff in the back and it never got over 195F. It has the LPD design so thick cold fluid bypasses the cooler so the transmission warms up to about 110F before the cooler starts working.

 

Good info! When you say "spin on filter" what exactly are you refering to?

Also, are you guys just replacing the stock radiator with a new stock radiator...or are there better aftermarket radiators available for competative prices?

 

The transmission filter in the 4runner and taco transmissions are just a screen like on a window at your house. Because of this they only stop things bigger than a golf ball.

So I installed a remote spin on filter adapter which allows for you to use a standard oil filter to filter your transmission fluid. The "oil filter" will get ALLOT more of the junk out of the fluid than the screen ever could and its allot easier to change.

When I installed mine I put in a Tee fitting on the inlet to the filter adapter and screwed in a temp sensor so I could avoid having to put one in the line (more risk for leaks). Also when you install a filter the order should be

TRANS OUTLET------FILTER ---- COOLER ------- TRANS INLET

Put the filter before the cooler.

http://www.summitracing.com/parts/SU...0/?image=large

This is the adapter I used on mine and mounted it up under the ARB bumper. The filter uses the standard PH8A filter but if it is too long (which I felt it was) you can use a PH16 which is the same diameter and threads but about half as long.

As far as change interval I change my spin on transmission filter every other oil change and top off for the lost fluid.


As far as the radiators go, OEM ones are WAY too expensive. I went with with a Spectra-Premium radiator from RockAuto.com for $130.00. Its a very good quality radiator for the price and IMHO on par and BETTER than the OEM one.

 

I'm not sure how the water is further east, but using distilled water instead of faucet water helps immensely as well in keeping corrosion to a minimum out on this side of the country.

You may not think it makes a huge difference, but it does.

 

Awesome info, do you have any pics of the install?

 

And thats one thing allot of people don't realize. They thing its only well water thats the problem but when you look at all the chemicals they put in municipal water. You have fluoride, chloride and several other elements that when mixed with the metals of a cooling system and heated will over time cause harm.

When I changed my timing belt and water pump at 125K miles I drained the entire cooling system and refilled with distilled water and Toyota Red coolant.


Well four years later (which was three months ago) ago I did the timing belt and water pump again at 225K miles and replaced the radiator. The coolant I drained out was still nice and clear and red. The radiator which I cut open was still clean and shiny (I just didn't trust it after 9 years). In the 4 years the most I had done to the cooling system is add a little distilled water to the overflow bottle.

The root cause of allot of cooling system problems is the use of tap water and the lack of use of a quality anti-freeze with specific purpose additive package for the engine and cooling system metallurgy.

 

The radiator in my 99 looks just like that when I replaced it due to the trans fluid/coolant mix in my radiator and transmission. First thing I did once I got the trans and radiators cleaned up was to buy a external cooler and bypass the radiator. I installed a hayden cooler and a tru-cool external thermal bypass valve.