So for anyone who did the transmission cooler in the radiator bypass mod, to potentially avoid mixing of coolant and ATF, don't forget to plug those inlets where the ATF lines went!

About a year after installing my external transmission cooler, coolant started dripping out of those ATF inlets. It potentially can leak out very fast, depending on how your radiator "goes".

So here's how to plug them up reliably.

Step 1: Take out the aluminum hose fitting from the radiator. Both the fitting and the radiator threads are fine thread aluminum, and are known to leak and break off by themselves. There is very little thread surface. If you take them out once, don't plan on putting them back in and getting a good reliable seal. The threads will strip.

As a work around get a 1/2"-13 coarse thread bolt no more than 1 inch long.



Take off the large and the compression washers from the old fitting and put them on the bolt. Liberally dab the washers and the bolt threads with 2 part epoxy to make sure it will never come loose.

Step 2: Tap the radiator inlet for the 1/2"-13 bolt. The aluminum is very very soft.



Step 3: Put in the bolt and torque it down to 1-2lb/ft at most, just enough to engage the compression washer. The aluminum threads are very soft, so the epoxy will be the one making sure everything stays together.




Step 4: Go back to thinking how reliable Toyotas are

 

I just ran a hose between the two:

 

Just run a hose like Mt Goat did, or just a vacuum cap.

 

Caps and hoses is just more places to leak. This mod supports 500psi

 

This issue is pissing me off, it seems like it is just a matter of time until this happens to our rigs, this could be a major expense that is not preventable. How many of you guys have bypassed the cooler and where are you running the lines. I seen a pic where a guy cut a hole through the rad support, it looked nice but I would rather not cut the truck. Any help would be great, I ordered a cooler today to prevent this from happening to my rig.

 

Daily Drive,
you are 110% correct I pulled the connector out with JUST finger pressure trying to pull the hose off and I stripped it clean out...Did'nt know that this would work so I ordered a new rad from advanced auto...?
Where did you get that size of bolt? I may give this a try and it may save me the cost of a new radiator right now. Where did you find the 2 part epoxy?

Later

 

I just used a tube on mine and I am not looking back

You can get 2 part epoxy anywhere, lowes, homedepot, ace, advanced, autozone, oreillys

 

If the locknuts that hold the tranny cooler close to the tank are tight, no coolant should leak.

The transmission cooler in the radiator is an extremely efficient cooler because it is liquid on liquid. This is the reason Toyota uses this type instead of the external transmission cooler. However it can only cool the tranny fluid to the water temp. If this mod were to be done better the original tranny cooler should be used as a pre-cooler for the external tranny cooler.

This way the tranny fluid is cooled down to a temp that the external tranny cooler can cool better with the cooler air temp.

Also those connections on the radiator tank should not fail unless messed with. If you were to just tap into the tranny line after it leaves the radiator the hardware on the radiator would not be put under any stress.

 

That's a pretty standards size bolt, you should be able to find it at any store Sears, Lowes, Home Depot, etc... Same places sell 2 part epoxy for about $3 a tube, in the glue section. Or you can use any type of resin based glue too. Doesn't really matter.

 

can i use the tranny cooler as the oil cooler after swithcing to a 5 speed?

 

No, different flow and pressure requirements.

 

Just had my cooler burst a few months back with 160,000 on my T4R. Flushed and flushed, but 3 months later and I'm in the tranny shop doing a complete donor swap!!! I really wish I had known about this possible nightmare when I first bought my truck. A simple mod could have saved me 2K!! For all those that haven't, DO THIS MOD!!!

 

For an engine oil cooler you want some beefy hoses for starters:

 

I know I'm quoting this a few months later, but to clarify for future readers, the reason people are getting external tranny coolers isn't so much because they want even cooler fluid than they had before, they are doing it specifically to replace to stock one. The reason is because the stock cooler is a defective design - not in how good it cools, but in the fact that it will rupture inside the radiator and mix the ATF with the coolant and in turn, ruin your tranny.

If you run both the stock and aftermarket coolers together, then yes, you would be getting even cooler fluid to the tranny, but you are defeating the purpose of this mod which is to prevent the "strawberry milkshake", not to get colder fluid to the tranny.

If your tranny is getting too hot and you want an external cooler for that reason, don't piggyback it with the stock one, bypass the stock one and get a bigger external cooler.

 

where did you get that beast at?

 

The sandwich plate adapter with thermostat was made by Mocal (part # OTSP1) Ordered from here:
http://www.batinc.net/mocal.htm

The cooler is an Earl's oil cooler (part # EAR22510) with the optional bracket (part # EAR1725) There are lots of places to buy Earls parts (like Summit Racing), but the cheapest I found was Barnett Performance in Atlanta 800-533-1320. That cooler was biggest cooler I could fit in the spot I had available. They make lots of different sizes so measure the place you want to put a cooler and pick a size that fits. Don't forget to leave room for the fittings.

I would suggest installing a oil temp gauge first to see what temps you're running.

The hoses are bulk (cut to fit) from an local oil field supply.

 

WOW....now THAT'S an oil cooler O_o

 

summer bump seems to me this will be happening to a lot of you auto tranny guys at some point or another. Should almost be it's own sub forum ....

 

i thought 4runners came with a oil cooler mine does its got a hose that connect to the side of the t-stat housing

 

Yes, there is also a factory oil cooler (liquid to liquid heat exchanger).