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After installing Oil pressure/temperature and Automatic Transmission Fluid Temperature guages, I was shocked to notice that the Automatic Transmission Fluid temperature after a 50F day with 20 minutes of normal driving, measured just before the OEM cooler (I figured was worst case), was 220 F! Running at this temperature, the ATF could be expected to last approximately 25,000 miles before total fluid replacement was required. Well, that just won't do. Solution? A Stacked Plate 16kgvw viscous bypass oil cooler mounted vertically behind the main grill. The ATF now operates within the range of 165-175 F with the same conditions. At this temperature, the ATF can be expected to last for approximately 100,000 miles. Maybe it's just me, but after installing the cooler and driving it hard for awhile, the shift points were as crisp as when I started. Previously, without the cooler, they didn't seem as crisp as the ATF heated up.
 
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Possible to post more details, please?

Interested in the one you used, cost, ease, etc.

Thanks

jerij
 
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I used a B&M stacked plate, 16kgvw oil cooler. The cost was approximately $50.00 including shipping from Summit Racing. Was relatively easy to mount vertically behide the main grill. The hose routing was easy too, just don't go under the radiator but rather to the driver's side near the wheelwell. I did not use the ties that go through the radiator, used plastic push pins with small brass L brackets mounted into some existing holes in the grill frame. If the weather ever warms up, I'll try to take some pictures.
 
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I'm going to have to remove my main grill to take pictures and right now the temperature is -10F and the grill is not removable at this time due to being frozen. Also, do not want to mess with plastic at these temps, will crack and break, and I can imagine what Toyota wants for that piece of plastic. When the weather breaks, I will take and post pics.

Picture of the cooler.
That is an amber light behind the Toyota symbol, comes on with running/head lights.
Please excuse all the dam salt.


Picture of the tie in to OEM cooler, it is inline after OEM cooler.
That brass tee hiding behide the lower line is where my trans temp sensor is mounted, just before the OEM cooler.
Top line goes to cooler, cooler return line goes to trans return, underneath top line.
Where the cooler lines makes the turns near wheelwell, I used dense foam pipe insulation to prevent chaffing of the lines.
I still don't know why they didn't have the OEM cooler in the radiator like every other car. All this extra plumbing for what?
 

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Bringing this thread back from the dead.
I have a 2004 and dont tow but my car is loaded to the roof and has a large roof top box, and 3 mountain bikes and I go over a lot of mountain passes and long dirt roads. I just got a portable hand held scanner, thanks to junebug1701s review of the elm327 bluetooth obdii scanner. It reads transmission temperature straight from the cars computer.
I am also seeing uncomfortable transmission temperatures, and totally agree with the OP. I see a tranny flush, mobil fluid and fitting a cooler in my future. I would strongly caution other RAVers out there to replace transmission fluid on the order of 20-30,000 not 100,000miles. FYI just cruising I have seen 195F as a trans temp. I would be mush happier with 160F.
 

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I just installed the same stacked plate cooler from B&M ordered from summit racing. It was the same low $50 price. I installed virtually the same way. What a difference. Nice low 160 - 180at most temps and the engine is 5deg cooler in many conditions due to the the factory heat exchanger (hockey puck) not causing the radiator to deal with another hot coolant loop.

This will save real money as fluid flushes are not cheap and this cooler is cheap.

I did this about 10,000 miles ago and am very happy with the results. Highly recommend. If lived some where super cold I would want a thermostat for the aux cooler but its not been a problem yet and if it becomes an issue I will get a thermostat. Summit racing sells thermostats also.
 

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Without a trans cooler, do our automatics really run fluid that hot? 220+?
 

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I can answer that question because my OBD reader, an ELM 327 unit uses the torque app running on an android phone and provides me the transmission temperature.

It runs at a good temperature during normal operation with a light load moderate ambient temperature, moderate grades ect.

Mine got all the way up to 237 at one point during my year long road trip. I was in new mexico it was about 90 degrees out and I had a substantial load in as well as three bikes on the roof and a coffin sized hard roof top luggage box (old yakima rocket box). I was also going uphill on a steep road in second gear at about 4000 rpm and had the AC running. When I would pull over and shift to park it cooled down to 190 which was engine temperature rather fast. Both electric cooling fans were running full blast.

Look at the Toyota maintenance guide they know the ATF fluid gets hot in extreme use, as they specify checking and flushing if burnt every 20,000. They give a definition of hard use and I check every single point except towing.

Transmission fluid life and operating temperate are directly related. At 160-180 fluid should last 100,000. At 250 its more like 5000 to 10,000. Toyota should admit an upgraded cooler is needed for towing rather than 20,000 mile fluid changes IMHO. However I can be too critical as many manufactures still have coolant loops that go into the radiator rather than stand alone units or heat ex changers. The problem with an in radiator unit is that a failure can lead to AFT and coolant mixing, and causing havoc on the transmission, engine or both.

My only regret with the B&M stacked plate is that I did not do it sooner. I could have painted it a nice bling red that would look cool through the grill but I am lazy and left the black powder coat alone.

Installing inline with the OEM like noodle did is correct and allows the OEM heat exchanger (hockey puck) to act as a pre heater in cold conditions. It does take a little longer for the transmission to heat up in cold conditions. So far the coldest it has been driven in since adding the cooler is 15 degrees.

A stacked plate cooler auto regulates to some degree as it expands more fluid passes through the plates as it cools it contracts and less fluid passes through the plates. Coolant always flows through the loop around the plates so it never restricts flow.

If I were to drive in extreme cold I would want to add a thermostat controlled aux cooler bypass loop.
 

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ATF

ATF is cooled with the radiator, at operating temperatures the coolant is around 220 F, the ATF from the transmission is hotter than 220F, so it gets cooled with hot rad coolant.

Coolant is under pressure.
Coolant is hot
Tranny fluid is very hot under normal use
Radiator may be hot but not as hot as transmission

Now it should make sense to change out transmission fluid every 1-2 years.
 

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I agree with everything Jay said. I put my Techstream on my '07 base today and ran some errands- coolant was running 187-192 even in traffic and A/C. Trans temp ran from 205-210 with one spike to 214 pulling a grade. This was a combination of city and highway, probably 40-50 miles total on a 92F ambient day. My Sequoia tranny only runs 175F pulling a 3K trailer through the mountains, but it has the towing package which includes a nice tranny cooler.

The Rav tranny could use a bigger tranny cooler, if I towed or worked mine hard I'd probably put one in. If it runs 210-220 I'll leave it stock.
 
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