Trans and coolant temp

[gen1]

Hi all, I was driving along a beach on the sunshine coast recently, and due to timing part of that trip was on high tide and in the soft sand. It wasn't particularly hot outside, but i watched the temps via TorquePro app for shits and giggles. Anyway, long story short, low range but pushing it a little through the soft sand so the car was working. I pulled up when coolant temps hit 110c and the transmission hit 117c. The temp gauge was still sitting on normal. Temps dropped quickly when i stopped, so i just adjusted my driving and carried on with no further issues. Question, what is considered the upper end of safe temps for the transmission? At what point does the warning light come on?

[Dicko1]

On the NW the transmission warning light comes on around 140 degrees. Do yourself a favour and get a lock up kit installed...will see a big drop in temps. I wouldn't put any faith in the cars dash water temp gauge. I rely on my scan gauge and also have an engine watch fitted.

[spot01]

Simple things first:
Were your tyres aired down enough, as too much pressure will cause much higher temps as the car works much harder.
Did you manually hold it in a lower gear to reduce trans slip?

[old Jack]

Hi all, I was driving along a beach on the sunshine coast recently, and due to timing part of that trip was on high tide and in the soft sand. It wasn't particularly hot outside, but i watched the temps via TorquePro app for shits and giggles. Anyway, long story short, low range but pushing it a little through the soft sand so the car was working. I pulled up when coolant temps hit 110c and the transmission hit 117c. The temp gauge was still sitting on normal. Temps dropped quickly when i stopped, so i just adjusted my driving and carried on with no further issues. Question, what is considered the upper end of safe temps for the transmission? At what point does the warning light come on?

Warning Light comes ON at 147C and by this time you have already started to do damage to your ATF.

You say you were in low range and this is good but in really soft sand you should also use sports mode so you are in control of the gear that you are driving in. If you drive in"D" then the AT ECU will select a gear that is too high and the torque converter will slip and this is what causes the ATF and engine coolant to heat up very quickly.

If you are doing a lot of this soft sand work then an MM4x4 Lockup kit will reduce both temperatures.

As others have said tyre pressure is everything, in really soft sand 12-14PSI and keep speed below 40kph, steer and brake gently. This is a good pressure to use in deep soft sand, if you are still having problems and get stuck then you can go as low as 8 psi to get you unstuck but you run the risk of tyre damage and popping the tyre of the rim.

OJ.

[gen1]

thanks for the replies. I'm no newbie to 4wding, but mostly around the high country, not often on the beach. Tyre pressures were down to 18psi, a compromise between the short dry sand stretch and the rest of the beach drive fully loaded. This was also suggested by a local. Transmission was held in third, manual mode as this allowed reasonable high revs without the car lugging. I was surprised at how quickly the temps rose, so was wondering really at what point they got too high. I know from experience with my old Land Rover not to rely on dash gauges, they may as well be painted on

[old Jack]

thanks for the replies. I'm no newbie to 4wding, but mostly around the high country, not often on the beach. Tyre pressures were down to 18psi, a compromise between the short dry sand stretch and the rest of the beach drive fully loaded. This was also suggested by a local. Transmission was held in third, manual mode as this allowed reasonable high revs without the car lugging. I was surprised at how quickly the temps rose, so was wondering really at what point they got too high. I know from experience with my old Land Rover not to rely on dash gauges, they may as well be painted on

What tyres are you running?
2 psi can be the difference between getting stuck and getting through
If running passenger construction tyres then 14 to 16 psi.
If running Light Truck construction tyres then 12 to 14 psi.

You can be in 3rd and running high engine rpm and the torque converter can be unlocked.
Only way to know is to gradually reduce rpm until speed drops off, this is very hard to do when you are in deep soft sand and the ocean wants to gobble up your 4wd.
This is were either Lockup Mate or Auto Mate in manual mode really work well, they have been tested on the super soft southern beaches in South Australia.

OJ.

[gen1]

I actually had my Muddies on, this couple of days on a beach was the end of a much longer trip through outback NSW. Kumho MT51's are on my steelies for such trips. Noisiest bloody things I've ever had on a car! We weren't even close to being stuck, no issues moving off from a start when we had to stop for other cars that were getting stuck. At various points on that drive the torque converter was locking up in third, and its surprising to see the instant and dramatic drop in transmission temps. There had been rain the night before and the occasional afternoon thunderstorm, so while the sand was soft we weren't talking about the stereotypical dry powdery mid summer power sapping sand. I would have been quite happy to drop more pressure if needed. I am familiar with the Automate, as a friend has one, but for the one or two days a year i might go near a beach, and the fact that i don't tow, it's probably an unwarranted expense!

[Ian H]

It's not just the beach, a lock up kit helps transmission temps on long slow climbs in the high country too. If you don't need it for towing or around town and want to save a few bucks, get Lock Up Mate instead.

But having said that, I use AutoMate all the time, even in town.

[NTBenny]

The Auto-mate doesn't operate below approx. 40kph though is that right?

Benny.

[Ian H]

No, it operates lower as long as the engine isn't struggling and you have it set to operate in second, which is the default. It won't operate under a certain (user set) transmission temperature, measured in the pan, not the pipe. Mine is set at 50c but once it turns on, the trans temp can go below that setting and it still works.

On a long slow climb in the high country a few weeks ago, a mate had his Grand Cherokee (yes, I know, don't say it) go in to stop mode due to overheating. The Paj wasn't even close.

[gen1]

I find long low range hill climbs, such as Billy Goats Bluff track in the High Country will not get the transmission hot at all. That track isn't difficult but it is long and steep. Last week the trans temp topped out at 93 degrees. It gets much hotter on long hill climbs on the bitumen, where the speeds are higher but obviously not high enough for adequate air flow. That has me rethinking the large spot lights bolted to the bullbar.

[Mundy55]

This doesn't change any of the recommendations above but virtually all vehicle temperature gauges are "normalised", meaning that if the operating temperature is within the acceptible range, the gauge sits mid point and doesn't fluctuate. This stops anxiety to drivers who would otherwise worry about the rising and falling temperature shown on the gauge. However, the downside is, if the temperature gauge starts moving up, stop immediately as you are starting to do damage already, as indicated by OJ.

[m_and_m]

The Auto-mate doesn't operate below approx. 40kph though is that right?
Benny.

Note quite.
In 2H DRIVE it switches back to DRIVE below 30 kph an unlocks the TCC to avoid the 1 gear quirk.
In 2H SPORT, it doesn't switched back to DRIVE below 30kph if you are in 1st or 2nd gear. (ie engine braking or climbing steep hills)
In 4LLc SPORT, it doesn't switch between DRVE and SPORT as the quirk doesn't happened in low-range. Instead it operates when above about 1600-200RPM in 2nd gear or above - speed isn't a consideration.
In 4LLC DRIVE - doesn't lock the torque converter - you're always best using SPORT mode when in low range.

Question, what is considered the upper end of safe temps for the transmission? At what point does the warning light come on?

Light comes on at 147degC. The oil starts degrading at 125degC. This is the upper limit before you should take action to reduce the temperatures.

No, it operates lower as long as the engine isn't struggling and you have it set to operate in second, which is the default. It won't operate under a certain (user set) transmission temperature, measured in the pan, not the pipe. Mine is set at 50c but once it turns on, the trans temp can go below that setting and it still works.

Once warmed up (at set point) it keeps operating until 5 degC below the set point. It will then deactivate, and let the temp climb back to the set point before activating again.

I find long low range hill climbs, such as Billy Goats Bluff track in the High Country will not get the transmission hot at all. Last week the trans temp topped out at 93 degrees

This wasn't my experience at all - mind you were were driving on very hot days. Before I had my lockup kit installed I hit temps of 130 degC - yes - above the 125degC limit mentioned above, but when you're in convoy with others who have lockup-kits you kinda don't want to hold up the group. (this was before I developed lockup-mate)
Once the heat gets into the trans it take a long time to get it out again. So, after the 1st hill you may be ok, but after the 2nd, 3rd, 4th the trans oil got really hot.
I did a video of lockup-mate being used when climbing billy-goat. The 1st half with the lockup-kit off, and the second half with it turned-on. During the second half, the transmission actually cooled down. I should post this video one day

[NTBenny]

Thanks Marshall.

Benny.

[gen1]

I've started to wonder if the Torque Pro app is measuring the trans temp properly at all. I've noticed that at even at relatively high temps that once the converter locks up the measured or reported temps drop significantly within seconds. I remember way back when i set up the app that there was a question somewhere about whether the formula given was for the Aisin or Jatco transmission. Might have to do a little more digging. Anyone have a quick link for the correct setup for my NX?