Still new here but have noticed several threads about a line rupture in the OE tranny cooler causing transmissions to be "steam cleaned" with coolant. Ebbsnflows, Brandyn85 (near the bottom) and whitemarlin all had similar stories of the cooler in the radiator failing with little warning. Potomacduck and Mycho also reported having this problem in the posts above. Mt Goat said that he has bypassed his OE cooler and maintained reasonable temperatures.

I would like to hear other opinions about bypassing the factory cooler. Hayden recommends an in-series installation. I also wonder if you could get around the in-series with a larger cooler and how big it would need to be.

 

How about replacing the lower radiator tank with a brand new one from the dealer?

Part no. is 16460-75180.

HTH

 

had I known it was a weak point of the vehicle, I'd have made that decision.

 

If funds permit, I would recommend replacing the lower tank if possible and adding an aux. cooler too.

 

Interesting idea. I wonder if that is just the tank or the tank and the lines. Has anyone else bypassed the radiators transmission cooler?

 

That's not possible, the heat exchanger for the ATF is inside the radiator. That is not a serviceable part, you'd have to replace the whole radiator. The part # you have provided is for the plastic overflow tank.

 

Which cooler did you choose, Mt goat?

 

I'm running the #4454, but it wouldn't hurt to go bigger if you have the space. Its also good to get it in front of a fan, either the radiator fan or add a small fan for it.

 

Bypassing the stock cooler is not an issue heat-wise as long as you get an auxiliary cooler rated high enough for your application. However, the factory coolers are plumbed the way they are to maintain a minimum temp for the tranny fluid. That is also an argument for placing an aux cooler upstream of the factory cooler so that a minimum fluid temp is assured. So if you live in a cold climate and bypass the factory cooler you might be operating the tranny at below ideal fluid temp. What that translates into performance and tranny longevity-wise, I dunno.

 

I can't really say this isn't a problem because I haven't run this setup in cold weather yet, but my 97 BMW 328i has the same setup from the factory (no radiator ATF cooler). I'll let you know this winter what my ATF temps are. My ATF cooling fan is set to come on when the ATF reaches 170 F with a Hayden 3647 controller.


The cooler I'm using also has a built-in bypass so cold ATF can go around the cooler:
http://www.importperformancetrans.com/coolers.shtml

 

Thanks for the input everyone. I'll try to do more research on the effects of cold environment on using these coolers and post up anything that I find. I live in the south east so hopefully that won't be an issue here. It seems like the bypass would work well enough to keep the ATF fluid moving until the transmission heats up to normal operating temperature. I don't think the coolant in the OE system would regulate the fluid temp before normal op temp anyway.

 

Well that's a good point, the coolant in the radiator is going to be stone cold until the t-stat opens.

 

The fact that they offer a bypass means that somebody thinks there is such a thing as too cold of fluid. I've heard the minimum temp should be around 175 degrees. I believe that cold fluid has trouble circulating - which can cause a variety of problems. How long it takes for a tranny to warm fluid on its own (without the benefit of picking up heat via the radiator) is probably a function of ambient temps and the grade of the road. I'm thinkin' the torque converter is the biggest heat generator so if you are cruising on flat ground at low speeds temps may take a while to rise.

It would be interesting for someone with the time and inclination to hook up a temp gauge and gather some data on passing through and bypassing the built-in radiator cooler at various ambient temps and road grades.

 

Sad to say, another reported case from Ohio4runner4x4.

 

Yes, this is indeed sad.

 

Hara-kiri?

Mt Goat, did you use the brackets to mount your #4454 or the zip ties? If you used the brackets, any pics? Also, how did you seal off the OE cooler?

 

sorry double post

 

Aaron, I like to use brackets. Another nice thing about the Long Tru-Cool LPD Transmission Coolers is they come with a good set of hardware to make brackets out of. The more you can support the cooler the better because all of them are just thin aluminum and subject to bending stresses.

Here's some of the coolers I've installed:

 

I just ran a piece of ATF cooler hose straight across from the inlet to the outlet (joined them together) and hose clamped it in place. That way if the internal ATF cooler ruptures I won't lose all my coolant.

 

Does anyone know the price of an OE radiator straight from Toyota (Grapevine, etc.)? I have an '01 with 134,000 miles and wonder if this may be a smart preventative maintenance item as I intend to still keep the truck for many years.

Andreas