Severe damage in 3,2, or L?

[jh26]

I was reading the owners manual for my new 2006 v8 and came across this:

Do not continue hill climbing or hard towing for a long time in the 3, 2, or L position. This may cause severe automatic transmission damage from overheating. To prevent damage, "4" position should be used in hill climbing or hard towing

I suppose this is because the torque converter doesn't lock up in those gears, but this makes it sounds like the transmission cooler is too small to handle going up hill. Say it ain't so!


So has anyone used a transmission temp gauge and watched what the v8 4runner really does when going up hills in various gears under heavy loads?

 

[Thai]

A better question is...why would you lock your tranny in 3, 2, or L for towing long distances up a hill, especially 2 or L?? For sure, 2 or L is used mainly for short distances only.

The recommendation for towing from almost every vehicle i know is...if you're towing, then use the gear below overdrive...that is, lock out overdrive (OD). Since your '06 4runner has a 5-speed automatic, when you tow, you should select/shift into gear 4 (the fifth gear is OD). Let the transmission computer do the thinking from there on out.

 

[TechWrench]

I was reading the owners manual for my new 2006 v8 and came across this:


I suppose this is because the torque converter doesn't lock up in those gears, but this makes it sounds like the transmission cooler is too small to handle going up hill. Say it ain't so!


So has anyone used a transmission temp gauge and watched what the v8 4runner really does when going up hills in various gears under heavy loads?

When under any type of heavy load, the torque converter automatically drops out of lock-up. The lock-up function is not designed to handle heavy torque loads. I think the reason for the warning is because when you manually select a gear, it stays in that gear, while leaving it in 4 allows the trans to up and down shift as needed. As for the cooling issue, the trans is cooled by a small cooling tube in the radiator, which works well for most 'normal' driving situations. If you have the HD towing package installed, they install an additional inline cooler to handle the additional heat load the trans generates.

 

[Thai]

Re: Re: Severe damage in 3,2, or L?

If you have the HD towing package installed, they install an additional inline cooler to handle the additional heat load the trans generates.

I believe that all V8 4runners have the additional tranny cooler.

 

[khaug]

I recently returned from a 725 mile trip to Virginia International Raceway, towing my Porsche track car through the Blue Ridge mountains on I-77 and Virginia 58. The latter road involves miles of extreme grades, switchbacks, etc., getting over a mountain.

I used manually selected second and third gears for several minutes at a time to have the pulling power and compression braking I needed. The tranny overheat light never came on and there was no sign of thermal (or other) stress discernable. This was my third VIR trip towing my Porsche with our current 'Runner.

My owner's manual doesn't contain the language that you report, and I've always manually selected 2nd and 3rd gears when necessary. Same with towing with my prior 4Runner, a '98 3.4 V6. I have to personally interpret the language in your manual as meaning "Don't do this to an abusive or unreasonable extent".

I've towed my 4,000# rig with 4Runners for eight seasons now, totalling probably 35,000 tow miles, with no added tranny cooler. The fact that I replaced our '98 with our current '03 should tell you how I feel about 4Runner durability/reliability.

I hope this makes you feel better!

 

[jh26]

why would you lock your tranny in 3, 2, or L for towing long distances up a hill.

If the transmission is hunting between 4th and 3rd, you would want to lock it in 3rd to keep the RPMs up. Think about I-70 headed up Vail pass. As for keeping it in 2 or L, I've done plenty of off-road trails where I never got higher than 2nd gear/lo range on a manual transmission. But I've never done much off road with an automatic. What I'm wondering is just exactly how much does this run up the transmission temp. I probably need to ask that question on a RV forum.

And yes, all V8 4runners have an aux trans cooler, not just the radiator tube.

 

[jh26]

I've towed my 4,000# rig with 4Runners for eight seasons now, totalling probably 35,000 tow miles, with no added tranny cooler. The fact that I replaced our '98 with our current '03 should tell you how I feel about 4Runner durability/reliability.

I hope this makes you feel better!

It certainly does! Thanks...

 

[JB.]

Re: Re: Severe damage in 3,2, or L?

I think the reason for the warning is because when you manually select a gear, it stays in that gear, while leaving it in 4 allows the trans to up and down shift as needed.

I wish that this were true. It won't upshift, of course, but you can't stop it from downshifting when 3rd is selected.

 

[Northof49]

I've always manually selected 2nd and 3rd gears when necessary. Same with towing with my prior 4Runner, a '98 3.4 V6. I have to personally interpret the language in your manual as meaning "Don't do this to an abusive or unreasonable extent".

Exactly. Of course using different gears for some more power or engine braking when needed is acceptable.....that's why the gear selector has all them fancy different numbers.

The manual is written the way it is, because if they don't throw in at least some warning....then some idiot will leave it in 2nd the whole time he's towing on the highway with the engine spinning 12,000rpm for 6 hours and wonder why his truck broke.

 

[TechWrench]

Re: Re: Re: Severe damage in 3,2, or L?

I wish that this were true. It won't upshift, of course, but you can't stop it from downshifting when 3rd is selected.

I have never had a reason to put the trans into manual L or 2 before tonight, so I made that statement based on experience with some other cars. I was wrong.

After making my earlier post, I did some experimenting on the way home from work and learned a few things. I found that if you put the trans in L, it starts off and stays in 1st gear. If you put it in 2, it starts off in 1st and will upshift and down shift between 1st and 2nd normally, but no third. Same for 3, 1st, 2nd, and 3rd up and down, but no OD. (I have the '03 V6 with 4spd)

In any case, I still don't understand Toyota's warning about leaving the trans in 3, 2 or L. As long as you don't exceed the max RPM or road speed, I don't see the problem.

 

[JB.]

Re: Re: Re: Re: Severe damage in 3,2, or L?

I have never had a reason to put the trans into manual L or 2 before tonight, so I made that statement based on experience with some other cars. I was wrong.

After making my earlier post, I did some experimenting on the way home from work and learned a few things. I found that if you put the trans in L, it starts off and stays in 1st gear. If you put it in 2, it starts off in 1st and will upshift and down shift between 1st and 2nd normally, but no third. Same for 3, 1st, 2nd, and 3rd up and down, but no OD. (I have the '03 V6 with 4spd)

In any case, I still don't understand Toyota's warning about leaving the trans in 3, 2 or L. As long as you don't exceed the max RPM or road speed, I don't see the problem.

I generally drive around town in 3rd. When I want power, I usually want it without the nearly full second delay of a downshift. Even in third, I sometimes get nailed by a downshift.

 

[Koz]

I think the problem that Toyota is trying to avoid is overheating due to lazy people who leave the trans in lower gears and over-rev the trans when it should have up-shifted, under loads for LONG periods. I honestly think that there will not be any problems off-roading or towing if you use the tallest gear when possible.

Koz

 

[Thai]

As for keeping it in 2 or L, I've done plenty of off-road trails where I never got higher than 2nd gear/lo range on a manual transmission. But I've never done much off road with an automatic.

Off-road is a different story. I thought that you were talking about towing long distances in these gears. And i now see that there is a reason to do so.

 

[Northof49]

I think the problem that Toyota is trying to avoid is overheating due to lazy people who leave the trans in lower gears and over-rev the trans when it should have up-shifted, under loads for LONG periods. I honestly think that there will not be any problems off-roading or towing if you use the tallest gear when possible.

Koz

Exactly!