2024 Tacoma Transmission Overheating on Long Climbs Off-Road

[Lando]

A couple observations. I’ve climbed mountains in a ‘98 Chevy and never had to shift to 4L. Long slow drive up switchbacks.

I feel this is a Toyota issue and it hasn’t been addressed because it’s Toyota, it’s not mainstream of an issue enough for them to bother. To me, 4L isn’t meant for off road climbs where you have traction. I’ve only used it in specific instances where 4H was stuck.

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[izzy]

A couple observations. I’ve climbed mountains in a ‘98 Chevy and never had to shift to 4L. Long slow drive up switchbacks.

I feel this is a Toyota issue and it hasn’t been addressed because it’s Toyota, it’s not mainstream of an issue enough for them to bother. To me, 4L isn’t meant for off road climbs where you have traction. I’ve only used it in specific instances where 4H was stuck.

Really depends on the grade and if the torque converter is locked or not.

If the torque converter isn't locked in 4Hi 2nd gear 15mph, yeah it's gonna make a ton of heat.

4Lo 2nd gear 15mph is maybe 1000rpm higher, and the torque converter is for sure locked.

I don't see the issue with using the gearing to help you out.

4Hi:

4Lo:

More 4Lo:

I'd say unless you can maintain 15mph and you're in S1 4Hi, you're gonna be putting heat into the transmission. First gear is actually pretty long imo in 4Hi, too long to be used when not crawling along. You can go like 35 in 4Lo, just gotta let rev it out so it shifts.

 

[Someguysomewhere26]

I hear you 100% it’s less of it being a “issue” of course I can throw it in 4 low just as much as I can add an additional trans cooler as well.
More as it’s not typical for majority of vehicles to behave this drastically requiring the use of 4low in a lot more situations.
In my absolutely meaningless opinion of this is how it was designed Toyota should’ve said so from the start.
“hey the way we geared this engine with the trans you will need to throw it into 4 low in more situations then before to avoid overheating this is normal ect.”
The silence is what concerns me.

 

[izzy]

I hear you 100% it’s less of it being a “issue” of course I can throw it in 4 low just as much as I can add an additional trans cooler as well.
More as it’s not typical for majority of vehicles to behave this drastically requiring the use of 4low in a lot more situations.
In my absolutely meaningless opinion of this is how it was designed Toyota should’ve said so from the start.
“hey the way we geared this engine with the trans you will need to throw it into 4 low in more situations then before to avoid overheating this is normal ect.”
The silence is what concerns me.

I agree, more instruction would be good.

Publishing instructions for driving offroad is probably legal departments worst nightmare (or close to it) since it opens them up to "why did you deny my warranty claim, I was just driving on a trail! It says you can do that in the instructions!"

but maybe, let's see what Toyota does.

 

[Someguysomewhere26]

Yeah, you make a good point. I guess I didn’t think about that part.
I feel like they could almost make it a promotional thing Toyota’s four-wheel-drive system, and just kind of slip on there 4l needs to be used on climbs. Lol

 

[izzy]

Yeah, you make a good point. I guess I didn’t think about that part.
I feel like they could almost make it a promotional thing Toyota’s four-wheel-drive system, and just kind of slip on there 4l needs to be used on climbs. Lol

Part of the strategy for keeping the TC unlocked is to allow the engine to rev so you can build a little boost.

When you have gearing on your side, the TC can lock up and you'll be making boost anyways cause you've got some RPM, plus you're utilizing the horsepower more than the torque.

Torque converter multiplies torque at the cost of heat, 4Lo also multiplies torque but doesn't generate heat.

I have a feeling with a shorter rear end you could probably get away with less 4Lo use, 4.88 maybe. It just happens that right at 10-15mph, which seems to be the sweet spot for long offroad uphill grades the TC is unlocked in first gear.

It's even worse if you let it shift in D cause it'll hang out in 2nd gear at 15mph which is wild haha. We did a full day of offroading around Hollister OHV and then drove all the way back to SF in traffic and still had 220 miles range (filled up in Hollister). Fuel efficiency offroad seems decent to be honest and we were never in "D", always S1 or S2 in 4Lo.

Trans tuning needs adjustment in 4Hi at the very least.

 

[Lando]

Part of the strategy for keeping the TC unlocked is to allow the engine to rev so you can build a little boost.

When you have gearing on your side, the TC can lock up and you'll be making boost anyways cause you've got some RPM, plus you're utilizing the horsepower more than the torque.

Torque converter multiplies torque at the cost of heat, 4Lo also multiplies torque but doesn't generate heat.

I have a feeling with a shorter rear end you could probably get away with less 4Lo use, 4.88 maybe. It just happens that right at 10-15mph, which seems to be the sweet spot for long offroad uphill grades the TC is unlocked in first gear.

It's even worse if you let it shift in D cause it'll hang out in 2nd gear at 15mph which is wild haha. We did a full day of offroading around Hollister OHV and then drove all the way back to SF in traffic and still had 220 miles range (filled up in Hollister). Fuel efficiency offroad seems decent to be honest and we were never in "D", always S1 or S2 in 4Lo.

Trans tuning needs adjustment in 4Hi at the very least.

Well said and this makes sense to me. I guess comparing what I’m used to in my old Chev doesn’t work here as a n/a V8 vs a turbo 4.

I need to rejig in my head what 4L is for and when to use.

An external trans cooler would have been nice though.

 

[Someguysomewhere26]

Yea guess we just gotta thug it out in 4 low hope they say something about it.
Ima lose my mind if the 2027 comes with a bigger trans cooler. lol

 

[izzy]

Yea guess we just gotta thug it out in 4 low hope they say something about it.
Ima lose my mind if the 2027 comes with a bigger trans cooler. lol

Just another thing to leak tbh haha

The other side is the trans shifts pretty poorly when it's not at operating temp 180-200F. so the trans cooler would need a thermostat so it's not open when you start the truck and it's like 40F out or whatever

 

[Someguysomewhere26]

Crazy part is I’m pretty sure ones with tow package have a trans cooler which I have….

 

[izzy]

Crazy part is I’m pretty sure ones with tow package have a trans cooler which I have….

No trim of 4G is equipped with a trans cooler factory, tow package or not. Trans fluid is pumped through a separate portion of the engine radiator to cool it.

Any trim above SR auto gets a sandwich plate style oil/coolant heat exchanger, which is barely an oil cooler imo.

Done several long uphill climbs offroad and never saw the trans go above 245F. Usually settles around 235F, acceptable temp.

Worst case just double the severe service schedule and do a drain/fill every 30k.

 

[TacoKiwi]

I have not sprung the trap yet and was going to go for a 2025/6 TRD OR manual but now revised that to currently looking to get the right deal on a TRD OR Premium Hybrid. Will install a cooler on the return line in the radiator cooling circuit. Will use proper flared fittings etc not the stupid hoses and hose clamps. One cannot cool a tranny with hot water from the radiator but it still needs to be in the loop for keeping the tranny warm in the winter!!

 

[Someguysomewhere26]

Well dang,
Not having one at all is even crazier thought it just sucked.

 

[izzy]

Well dang,
Not having one at all is even crazier thought it just sucked.

To be honest, even the OE cooler from 3G would probably cause the transmission to run too cool in cold climates.

But this same size cooler with a thermostat set to like 200F would probably be fine and help some.

 

[Someguysomewhere26]

I think a lot of transmissions have a way to heat up now probably thermostats like you mentioned

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