A/T Oil Temp light came on, in 4wd, with diff locked, driving on the beach

[f250ben]

Soooo this happened today. Not sure if this is a big deal or not, but here's the background.

206K miles, limited maintenance history. I've had the vehicle for about 8K miles, its had no drivetrain issues that indicated poor maintenance or abuse, but its not one of those impeccably maintained vehicles with service records every 5K for the life of the vehicle.

Drove about 10 miles down the beach Saturday, camped saturday night. Tire pressures low at 12 PSI, sand wasn't too soft. Kept 4WD and center diff locked the whole time. No problems.

Broke camp this morning, raised tire pressures to 20PSI because 12 was too low, and not stable. Drive another 15 miles down the beach. A/T oil temp light came on right at the end for about 30 seconds. I was cruising between 20 and 40 depending on the sand conditions. It came on right after a bout of cruising at 35-40ish.
Light went back off, code reader didn't find any codes. Nothing leaking or broken underneath, I didn't hit anything. We turned around and drove 25 miles back on the same beach with no issues, and drove another 150 miles back home. No further problems.

What do I do next? I'm not sure if this was a fluke from driving too fast with the center diff locked, or what. I feel like i need to at least do a full tranny flush/fill. Really not sure what to do past that. Is this an actual indicator of a potential problem, or could this have been a non-problematic fluke?

Obligatory pic of the rig on said beach trip...

 

[f250ben]

note: This was at Padre Island National Seashore on the South Texas Coast. Temps were in the high 40's today on the beach.
Also, I'm not sure how long the light was on before I noticed it, but it went off within 1 minute of me noticing it. Seems to me the temps couldn't have actually been too high, they would have taken longer than that to cool down again?

 

[hinmo24t]

were you driving those speeds in 4l or 4h?

 

[ghs215]

Transmission fluid is dyed red. You need to get a sample of your fluid and check against the color chart (google it).

Dark brown or black ATF can be an indicator of a transmission problem, vehicle abuse, or fluid that has far exceeded its useful life.

 

[Levinz11]

Eh. Probably no biggie. If in 4hi you might have been riding with the torque converter unlocked.

I've done some time on the Outer Banks and used 4low so it would grab a gear and stay there.

Get a USB dongle and start watching those tranny temps.

 

[shmabs]

If you were in 4 hi, and letting the transmission shift itself, a high temp is not out of the ordinary.

As others have mentioned, if 4 low works for the situation then use that. Also, pick a gear that works well for your given speed, and use that. At the speeds you described, I can imagine your transmission was probably shifting a lot, which generates heat.

 

[hinmo24t]

If you were in 4 hi, and letting the transmission shift itself, a high temp is not out of the ordinary.

As others have mentioned, if 4 low works for the situation then use that. Also, pick a gear that works well for your given speed, and use that. At the speeds you described, I can imagine your transmission was probably shifting a lot, which generates heat.

when people talk about selecting a gear (4,3,2,L) the truck will shift only up until the gear selected and not beyond it? you dont start in 2,3, or 4 or else you wouldnt move right?

 

[shmabs]

when people talk about selecting a gear (4,3,2,L) the truck will shift only up until the gear selected and not beyond it? you dont start in 2,3, or 4 or else you wouldnt move right?

I'll have to go try to be 100% sure, but my understanding that the gear you select is the highest gear the truck will shift into. For example if you select 3 from a stop, the truck will shift 1-2-3 as speed and rpm increase, but will not go beyond 3.

Thinking back to yesterdays adventure in the snow, that seems correct.

 

[Bumbo]

Not normal in my experience, but it could also be a fluke.

I drive around pretty regularly in heavy sand, both in 4Hi and 4Low and in hot desert environments… have yet to see any AT temp warnings.

Probably best to proceed with a fluid change and keep monitoring.

 

[Legender]

That is how my 4.7L Tundra works. Only has D 2 and L... sometimes I drop it too far and it ends up in 2nd. Won't shift above that, but then RPMs tell me something is wrong. I don't get but a few yards when I notice so no over revving.

 

[Bumbo]

when people talk about selecting a gear (4,3,2,L) the truck will shift only up until the gear selected and not beyond it? you dont start in 2,3, or 4 or else you wouldnt move right?

That is correct… you are selecting the max gear and it starts off in 1st gear.. I do this often to prevent bogging down in the sand from an up shift or to hold a gear at speed.