Light Towing 3kmiles with the 2.7

Hello Tacoma World,
After doing some exhausting research and coming to grip that my 2017 2.7l 2wd automatic is just not as cool as your v6 supercharged 4x4 w/tow pack. But, after finding out I have no transmission thermostat I am wondering if I should still install the aux tcooler? I will be towing a small single axle uhaul in August/September through the mid west to California. I just want to do as much preventive maintenance as possible and keep this little truck in good shape. I will likely not be towing more than 1500 pounds. So if I cannot pin the Tstat open (because I don't have one or it is electronically controlled) will that be an issue for me? Or will the trucks brain be able to handle it? I did pick up an SGII to monitor the Temps. Any input on my puny four banger would be very much appreciated.
Thanks in advance TW
OverlandRooKiE

 

1,500 lbs? Hook it up and go, you'll be fine.

 

To be honest I'm not entirely sure how much weight I will pull but I am under the impression it maxes out at 3500 which I feel is too much for that truck, so I will try to be around +/- 2000 pounds. I already purchased the aux. cooler. Would it be detrimental to install it or ultimately a good move for driving in the high ambient temps?

 

Hello fellow 2.7 Taco owner. I did this mod on my 2019, and I recommend everyone add the cooler to protect the transmission. I use

$152 ScanGauge - SG2 II Ultra Compact 3-in-1 Automotive Computer with Customizable Real-Time Fuel Economy Digital Gauges , Black , 5"

ScanGuage to monitor my Temps and I was hitting the 200s on my daily commute here in SoCal driving up several steep grade. I used LPD4589 Cooler. Since the install, the highest I reached was a stop and go commute from OC to Camarillo on the 405 where I touched 158 degrees. Otherwise, I hit 150 max on my commute in 90+ degree weather.

 

For short trips around town on level ground near sea level maybe.


At some point you'll need to cross some mountains with elevations near, or over 10,000' to get from the midwest to California. I'd want a transmission cooler for that. Also, your engine loses 2-3% power for every 1000' above sea level and max tow ratings should be reduced to account for that. If you're going to be at 10,000' that 3500 lb tow rating is closer to 2500 lbs.

With a transmission cooler I think you'll be OK as long as you can keep things under about 2000 lbs. Remember, the empty trailer weight will be 700-1000 lbs so that doesn't leave much weight for cargo on the trailer.

Don't drive in OD. Don't be afraid to manually drop down to lower gears in mountains to keep engine speed up even if you can't do more than 40-45 mph. At higher elevations they sell 85 octane gas as regular. Spend the extra for 87 octane. Especially when towing.

 

@Marshall R, thanks for the insight especially with the 87 octane, I will keep that in mind. I have been trying to figure out if there is any point in adding the cooler w/out having the Trans Thermostat. It sounds like I should just go ahead and install the cooler and feel better about it being there than worry about it not being there. I purchased the
Aphyni Long Tru-Cool LPD Transmission Oil Cooler 4454 18,000 GVW can anyone confirm how many quarts ATF is added to the overall system? I have read around 1.6 quarts. My plan is to install it and add enough ATF to get to the dealer and have them do a Transmission fluid flush (the truck is approaching 80k and I want to have them change it even though they said at 100k) and fill and just want to make sure I have an idea on total capacity, even though they will have a visual on the dip stick, I am just a little confused with not having the thermostat how to i open the system to let it cycle?

 

Make sure your tires are properly inflated, including the trailer. I run 35 psi (cold) on my truck, which is higher than the recommended pressure, but I'd rather be a bit high than low.

 

Have trust in the Toyota engineers over randos on the internet.

 

Don't overthink it. Send it.

 

Keep within the tow rating and it will be fine. To be clear the V6 only has the tsat for quick warming, for improved fuel economy. Check to be sure, I thought the 2.7 still had the trans cooler built into the engine coolant radiator.

 

1500 lbs is the absolute max I would tow with my 4 cylinder.

These trucks lock the torque converter in 4th, 5th, and 6th, so if you stay in those gears and keep the torque converter locked, you'll never heat up the fluid enough to cause an issue. The fluid really heats up when the torque converter slips. The torque converter can slip in any gear, so you want to stay in a low enough gear where the truck won't try to unlock the torque converter for an extra boost in power.

The truck isn't smart enough to know how long you'll need that extra boost. If it doesn't think it needs to downshift, it won't. You have to pay attention and be smart and use S mode to prevent it from doing things that can get you into trouble. The truck can stay in 6th gear at 45 MPH at 1600 rpm with the torque converter slipping 300-400 rpm and generating a lot of heat and you'd never know it if you weren't paying attention. Driving in S4 at 2100 rpm at 45 MPH with a locked torque converter, you'll almost certainly cool the transmission down more than heat it up. (the moving air underneath the vehicle can cool the transmission when there isn't enough heat being produced from TC slip.)

When towing, I recommend using ECT power all the time because it really does a great job keeping it in the gear you actually want rather than trying to keep it in the highest gear possible which is bad juju when towing. Fuel is kinda pricy, so you can leave it in S mode with ECT left off and shift it yourself and save a little fuel if you know what to do. For towing, I would recommend leaving it in S4 until you get to 50 MPH, and only use S6 when going downhill. S5 is fine if you're going fast enough on flat ground, but if you catch the torque converter slipping in S5, manually bump it back to S4. If you find yourself going up a steep hill and start slipping in 4th gear (happens all the time on I-70 in Colorado, even without a trailer), go ahead and go back to S3. When you drive in a lower gear, the gear does most of the torque multiplication, and the torque converter doesn't have to slip as much (I prefer to be in the 2000-3500 rpm zone if I must slip the converter). If you find yourself driving on an uphill section of dirt or gravel road where you can't really maintain at least 35 MPH (the lowest practical speed you can drive with a locked converter in either 4th or 5th), you need to pull off to the side of the road every 20 minutes and idle for about 10 minutes. My Tacoma adds about 1 degree F heat to the ATF every minute of driving in the above conditions, and I imagine when towing it could easily be double or triple that on the same type of slower roads with steep inclines. Baseline ATF temp for the Tacoma without slipping at all for a good long whole is about 170F. Driving 20 minutes up a hill when towing with a slipping converter will probably push the ATF temp to 220 or maybe 230, and that's when you really want to intervene if you can. When you idle, the coolant will circulate and cool down the ATF back to about 186 (same as coolant temp). It cools off pretty quick when the ATF is hot, but as it cools down you get diminishing returns. I don't know exactly how fast it cools down though as I haven't done this long enough to get hard data. What I do know however is that when the truck is turned off, The ATF cools down VERY slowly. Roughly 2 degrees every 3 minutes.

TLDR I don't think you need a transmission cooler. You can simply drive in ECT power mode to mitigate TC slip in higher gears, (the primary source of heat in ATF), and if you do catch yourself going up a hill on a slow road, you can just pull over and idle for 10 minutes every 15 or 20 minutes and the truck will cool itself off. The 4 cylinder motor doesn't really have a ton of power, and power is correlated strongly with the amount of heat you can produce in the transmission.

 

That is correct, this truck has no thermostat and no ATF external cooler. It does run the ATF through the radiator.

 

Thanks for the write-up, this is everything I was wondering about. It seems like it will haul a small moving trailer to where we want to go as long as I don't push it too hard. I did purchase a ScanGauge and will for sure use that but I will likely go ahead and install the aux tcooler just as a failsafe.

 

I looked in my 2018 owner's manual, and the fine print requires a brake controller for trailers over 1,000lbs, even with the ultimate 3,500lb tow rating.

 

Those single axle U-hauls don't come with brakes. And the larger ones come with surge brakes.

OP you'll be fine. Heat comes mainly from shifting. If you get up to speed and it keeps trying to downshift or unlock the TC, lock out your top gear and keep moving. Don't be afraid of high RPMs...use the power you need to.

 

Better solution: Rent the smallest truck they have that is rated to pull the car trailer (not the dolly), rent the car trailer as well. Put taco on trailer, load cargo in their truck. Save on the mileage and wear and tear on your truck.