ATF Cooler and Towing Questions

**Update**

Yesterday I dropped the transmission pan and replaced the filter and gasket, swapped out the ATF cooler, and bypassed the radiator portion of that "circuit". I then flushed the trans and tried my best to make sure that the fill level was correct. Now in "steps".

• The 1st thing I did was drain the trans and remove the pan and filter.
  • I then cleaned the pan and checked/cleaned the magnets. Everything appeared to be fine, but there was a fair amount of grey/black residue covering the inside of the pan, the filter, and the magnets. I used carb cleaner to clean the pan and magnets.
• Next, I installed the new WIX filter replacement kit (filter, O-ring, & gasket), and re-installed the pan.
• Then, I proceeded to disconnect the ATF cooler, taking note of where each line went.
  • I had to remove the OEM horns at this time as well to accommodate the fitment of the new cooler. I have an aftermarket 150dB horn that is mounted on the passenger side and is not visible in the pictures.
• I disconnected the lines from the radiator portion of the "circuit" and connected them directly to the 2 rigid portions passing through the radiator mount - bypassing the radiator.
  • The hose that came with the new cooler was a different inside diameter than the nipples on the radiator, so (for the time being, until I get a new hose to loop the in and out of the radiator portion) I used the rubber "dust covers" (or condoms if you prefer) that came on the new cooler to close off the radiator and prevent dust/debris from getting in there. Not sure if they are "kosher", but they didn't seem to have a problem when doing the idling portion of the procedure.
    • I tried to use some of the new ATF to lubricate the nipple, but no luck.
• Next, I used a self-tapping screw to mount a strip of steel bracing to the bottom portion of the bracing in front of the radiator to brace the right side of the new cooler
• I used more self-tapping screws to mount the new cooler to the new brace and the vertical support in the middle of the compartment.
• I was able to use the existing "input" line for the cooler, but the "output" line was too short and kinked when I tried to connect it, so I cut a length of new tubing from what came with the new cooler.
• Next, I disconnected the return line under the front passenger side of the truck.
• Then, (with a neighbor's help) I pumped about 3qts of new ATF into the fill port on the trans.
• We then fitted a tube between the return line and a gallon jug that I marked indications for qt levels
• We started the truck and let it push the new fluid through the system and out into the jug, until there was between 2-3qts in the jug and shut off the truck.
• We repeated this process about 3 times. The last time we set the parking brake, held the brake and moved the shifter through each of its positions - not sure if this does anything, but the videos I watched said it was an optional step.
• We then put about 3qts into the fill port on the trans and reconnected the return line to its nipple.
• We started the motor and let it idle to get the trans temp to about 120degF
  • The ambient temp outside was about 55degF, and after 45mins the trans temp was only at about 100degF. Probably not "kosher" but we decided to drive the truck around the block to help warm up the trans, which worked, and nothing either from my gauge cluster or from my tuner/indicator indicated any problems.
• When we pulled the check plug on the pan, nothing drained.
• At this point we had about 2qts left of ATF, so we pumped that into the trans, let it idle for a few more minutes to let the temp stabilize.
• When I pulled the check plug after adding the remaining ATF, it seemed to drain as the videos indicated it should, and I replaced the plug when it was a slow and steady stream/dribble. About 1qt drained out in this step before replacing the plug.

I have checked the vehicle both last night while it was idling, and this morning, and I do not see any leaks from any of the lines or from the pan and I believe that everything is "good to go". Next time, I'm not sure if I will do a flush, or just a drop and fill - any merits either way? The ATF I used was a Valvoline full-synthetic high-mileage that stated it was compatible with numurous transmissions including Toyota WS. We used almost 3gal of ATF in this process and cost $30/gal. The new cooler is a Hayden Rapid-Cool Trans-Cooler model 679, which I got at O'Rielly for about $65. The filter kit was by WIX and cost about $43. All-in-all, my total cost (including beer for the help) was about $200, coming in at about $100 less than what the mechanics wanted to do just the flush with no upgraded cooler and no filter change. I'll update when I've had a chance to drive around a bit more, especially as its warming up here in the Tucson area, on any changes I see in the trans and coolant temps(now that I'm blocking more of the radiator). Did I do things "right" in this process? If not, what should I have done differently or do differently next time?

Thank you all for your input and advice!

 

I thought about getting a bypass unit, but what ultimately led me to choosing a non-bypass unit is that I will likely never drive this vehicle in places where there are regularly sub-zero temps in the winter. My taco is a PreRunner, so I don't have 4x4 and I refuse to drive a RWD in the ice and snow - just my preference. We live in southern AZ and, even traveling to the high-country we never have to worry about the trans being too cool, rather the opposite. If things change and we move to a place that has frequent low-temps, I'll likely get a new truck that is 4x4 so I can be better equipped to handle the snow. It looks like both of you have 4x4 models, so if I were in your shoes I probably would have opted into a bypass-equipped unit as you can already safely handle the snow and ice.

I ended up orienting my new

$59 Hayden 679 Universal 11” Rapid-Cool Add-On Transmission Cooler to Enhance Cooling (not for direct replacement of the factory unit)

Hayden 679 the same way and bypassed the radiator portion of the circuit (something that I was seeing a lot of recommendations for on TW), so that the ATF runs solely between the trans and the trans cooler.

What model Hayden do you have installed on your rig? I opted into the Rapid-Cool 679.

 

That recommendation comes from the 1st gen era where the "pink milkshake" happened a lot. 2nd gens design doesnt nearly have that problem. Good thing about the rad circuit is it gets your trucks trans fluid up to temp quicker and helps it stay more consistent. Id recommend keeping it in the loop especially without any sort of thermostat on the trans cooler lines. You dont have to be anywhere close to sub zero temps to overcool the fluid.

 

So I should reconnect the radiator portion then? Running errands this morning my trans temp was between 120-130, but it was also 55deg outside. Not sure what the low end of the temp should be with normal driving but, in the vids I watched of the trans flush process, when they got to the portion where you check the fluid level at idle they said the trans temp should be 120-130 at idle. If I reconnect the radiator into the loop, do I need to flush the lines again to get any air out of them?

 

Ive seen that rumor about 2nd gens having an ATF t-stat popping up more and more lately..

Thats super interesting someone took the time to do that and log the temps. Ive always wondered about those lines so close to the cat..

 

Ideal operating temp is around the 160-180*f Mark for the toyota WS fluid as spec'd by toyota. As long as you have capped off the radiator barbs so debris dont get in, you should be able to rehook stuff back up (not sure if the top or bottom is the inlet on the rad) and the air will get pushed out pretty easily through the rest of the stuff (assuming you have inlet of new cooler at the bottom and outlet at top oriented on its side).

Temp check for trans fluid I think 130 is on the upper end, if you put the trans into temp check mode the dash will let you know when to check. I doubt the rad portion holds tons of fluid, but id hook it back up and put a half quart or so of fluid in the trans cold before doing temp check and then level check (its takes a long time for the trans to cool down to get back into temp check mode).

 

I haven't seen anything about a "temp check mode" - how does one do that? When I checked the fill level the trans was at about 120. I did indeed have the radiator capped off to prevent the fluid that was still in there from just running out as it got warm as well as to keep debris from entering the radiator. If I remember correctly, the trans fluid came into the top of the radiator, and out the bottom. As for the cooler, I connected it so that the fluid entered at the bottom and exited from the top.

 

The best way is to read the trans temp via OBD (needs to be 115-130F to check fluid level) but there is a built in temp check mode for those that don't have the ability to read trans temp.
https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/

 

I have the same model, the 679. It's super effective, almost too effective hah.



I do visit the mountains/snow every winter and do a lot of desert camping which can bring some pretty cold nights--so that's where I was thinking the bypass model would be useful, but we'll see.

I did opt to leave the radiator plumbing in place, inline with the 679. If anything, my line line of thinking was that it might help warm the transmission fluid somewhat in cold weather to keep it closer to that ideal 165-175 deg F.

 

You absolutely want to use the temp check mode on a level surface for proper fluid level, see the thread linked to below

 

Thanks! I'll have to try that. I currently have a BullyDog tuner connected to my OBD port and have it set to display trans temp among other things like MPG. If anyone is considering a BullyDog for their taco, I would NOT recommend it. It is not capable of doing the key things I wanted and they advertised, such as recalibrating the spedometer or loading a tune for better fuel economy when I'm not pulling a trailer or hauling stuff. When I called them to ask why I couldn't get into those settings on the tuner, they said that those options were only available for certain makes/models and that the options were fairly limited for Toyotas - all despite the description on their website not making any exclusions for certain functions on different vehicle makes/models. I'll probably never buy from them again after that experience. Were I to do it all over I'd probably have gone with a scangauge.

 

Checking the trans fluid using that method isn't too hard. Just a short strip of wire, a few shifts, and waiting for it to come up to temp, and you're good to go.

I have an UltraGauge that I've used in the past to verify the trans temp (in conjunction with the method in the aforementioned thread).

 

Oh yeah... might look into the HPTuners thread about a proper tune if you are looking for one. I have created some transmission tunes that definitely help with towing and while day to day mpg tunes really arent possible, under load (IE towing) can definitely be helped out as the "high load" tables target VERY rich fuel ratios which just wastes fuel.

 

I saw a preset tune package on my BullyDog that is supposed to be for towing (I believe it is titled accordingly), though I've never loaded it, so I'm not sure what exactly is adjusted or if its even more effective than running the "stock" tune.

 

I like your mounting setup. I just screwed mine into some steel strap bracing and that vertical support in the middle. Yours definitely looks more sturdy and attractive though. It sounds like I probably should reconnect the radiator. If I remember correctly, it ran into the top of the radiator, out the bottom and to the trans cooler is that how yours is? I deleted the "before" pics of the hoses cause I didn't think I'd need them as the project seemed finished.

 

Yeah most ditch the bullydog "tuner" I cant imagine it does anything as I dont believe it writes to the ECU at all. Theres honestly not a whole lot of performance left on the table on a stock truck thats not supercharged, that stated there are drivability aspects that can definitely make things better especially on the auto trans. (Speaking on the HPTuner side of the fence)

 

I am able to load "tune packages" from the tuner onto my truck, but I don't. I tried it one time with one of their "performance" tunes and almost immediately took it back to stock. While the tune package was loaded, I was getting on the highway, and my truck lost all power on the on-ramp and there was a sound like a lead pipe being drug across a chain-link fence. This was a few years ago. I believe I killed the ignition and restarted the truck to "fix" the issue long enough for me to get home and reload the "stock" tune. I have not had any other issues since but, needless to say, I've been afraid to try it again...

 

Not a 3rd Gen bro.

 

That is indeed a beautiful job. There are two types of "stacked-plate" coolers: "Stacked plate and fin" (like the Toyota) and "stacked-plate w/o fins" that has what I can only describe as: solid stacked plates with "zig-zags" in them which the fluid flows through that are actually part of the plate itself. It's hard to tell for sure, but yours appears to be the latter? (I wasn't sure if they made them anymore). That type presents much larger surface to the air flow without increasing the size of the cooler to do it. The ones I had on my trucks were made by Tekonsha. I still have one I removed and put away. I'll post a pic when I get a chance. FWIW, I think you did the right thing leaving the tank cooler in place. All the instructions I ever read advised not to bypass the factory tank cooler.

 

Thanks. I just picked up some 1" x 1" x 3/16" angle aluminum (don't know the grade, I assume it's 6061) and chopped it up and drilled mounting holes to create the mount. One of the mounts comes off the stock cooler bracket, another comes off the center bumper support, and the last one comes off of the radiator support bracket (I drilled a new hole in the bracket for this one).

I connected all of the pieces with stainless fasteners, washers, and Nylocks. I also used rubber washers between the metal surfaces at each and every location.

The result is very sturdy but also damps out a good amount of vibration to the cooler. I'm definitely happy with it overall.


I can double check tomorrow how I routed mine, I can't recall off of the top of my head.