LLY TFT guage readings

[gary_lucas]

Kind of weird, my TFT (Transmission Fluid Temperature / edge insite) gauge shot up to 229 yesterday while dropping off the new 5th wheel at near our storage site.

It is quite a climb into the hills we're parking it, however we were barely moving (30mph max)... So I was kind of surprised that the TFT shot up that high.

After reading around for a bit I didn't see anything that made me specifically worry. Normally I never see it past 215, and that's pretty rare as well.

[DmaxMaverick]

Did you have T/H selected (Tow/Haul)? Did the converter have a chance to lock? If not, the temps will be at the extreme under heavy load. Less than ideal, of course, but not abnormal. If T/H wasn't selected, the converter won't lock until well above 30 MPH (around 50), which will increase the temp considerably under load.

[gary_lucas]

I did have T/H selected, not sure what the 'converter lock' means.

Thanks for the reply.

G


Did you have T/H selected (Tow/Haul)? Did the converter have a chance to lock? If not, the temps will be at the extreme under heavy load. Less than ideal, of course, but not abnormal. If T/H wasn't selected, the converter won't lock until well above 30 MPH (around 50), which will increase the temp considerably under load.

[rapidoxidationman]

A torque converter can be thought of kind of like a clutch that always slips. It uses fluid to transfer power from the engine to the transmission (instead of friction plates, like an actual clutch). The fact that it slips is what allows your truck to be in gear at a standstill and not stall. The side effect of all this slippage is heat (generated by the friction of the fluid being pushed around).

When the truck is in motion, the torque converter can be locked up and it becomes a direct mechanical link between the engine and transmission. It doesn't slip any more, so less heat is generated. The side effect of being in Tow/Haul is somewhat harsher shifting because the T/C doesn't slip as much between gears (someone else can chime in on transmission programming and the ability of the lock to disengage between shifts for an instant).

[DmaxMaverick]

A torque converter can be thought of kind of like a clutch that always slips. It uses fluid to transfer power from the engine to the transmission (instead of friction plates, like an actual clutch). The fact that it slips is what allows your truck to be in gear at a standstill and not stall. The side effect of all this slippage is heat (generated by the friction of the fluid being pushed around).

When the truck is in motion, the torque converter can be locked up and it becomes a direct mechanical link between the engine and transmission. It doesn't slip any more, so less heat is generated. The side effect of being in Tow/Haul is somewhat harsher shifting because the T/C doesn't slip as much between gears (someone else can chime in on transmission programming and the ability of the lock to disengage between shifts for an instant).

Essentially correct, except the later models (Allison with TCM, specifically) will defuel (reduce power) and unlock the torque converter during shifts. This is part of the "torque management system" present in most all late model vehicles. The "harshness" felt during a shift is the power returning and TC locking again. The Allison TCM adaptive learn process will eventually calculate the power level, load and habit of the driver to smooth the shift process under varying conditions. Changing load, power level (program/module), or driving habit can cause increased harsh or soft shifts for a period (until it "learns" again). During the "learn" process, especially after making a significant change, can cause increased fluid temperature while under specific conditions, such as a "new" load (heavier trailer), low speed driving (less TC lock time), and driver habit (new/different trailer, new habit).

[gary_lucas]

Ok, that makes a ton of sense.

My trailer went from a 3000lb 18ft travel trailer to a 31foot 9500lb fifth wheel.

I'm having my mechanic do the oil and transmission fluid next week so at least the fluid quality won't be a problem.

I'm glad to hear the transmission will learn the new load, because it wasn't feeling as smooth as I'm used to, although with that much extra weight I didn't expect it too either.

Thanks DmaxMaverick and rapidoxidationman for the helpfull and detailed reply.


Essentially correct, except the later models (Allison with TCM, specifically) will defuel (reduce power) and unlock the torque converter during shifts. This is part of the "torque management system" present in most all late model vehicles. The "harshness" felt during a shift is the power returning and TC locking again. The Allison TCM adaptive learn process will eventually calculate the power level, load and habit of the driver to smooth the shift process under varying conditions. Changing load, power level (program/module), or driving habit can cause increased harsh or soft shifts for a period (until it "learns" again). During the "learn" process, especially after making a significant change, can cause increased fluid temperature while under specific conditions, such as a "new" load (heavier trailer), low speed driving (less TC lock time), and driver habit (new/different trailer, new habit).

[CoyleJR]

Gary_lucas
When you get the transmission serviced make sure that the mechanic knows to clean and reinstall the donut magnet inside the spin on filter. Additionally, the high trans temperatures are common with a large trailer. The trans picks up heat from the motor oil in the cooling stack and then it takes a long time to cool down. The motor oil cools down much faster. I run Dexron VI full synthetic in my 2006 because of the heat issue and because it requires full synthetic. I don't think your truck requires synthetic ATF but you may want to consider using it.

Good Luck
John

[gary_lucas]

Gary_lucas
When you get the transmission serviced make sure that the mechanic knows to clean and reinstall the donut magnet inside the spin on filter. Additionally, the high trans temperatures are common with a large trailer. The trans picks up heat from the motor oil in the cooling stack and then it takes a long time to cool down. The motor oil cools down much faster. I run Dexron VI full synthetic in my 2006 because of the heat issue and because it requires full synthetic. I don't think your truck requires synthetic ATF but you may want to consider using it.

Good Luck
John

All good, mechanic has the same truck (it's a different color, but same year / model) :D

He warned me that the trans fluid options weren't cheap.

[DmaxMaverick]

If you do a change to synthetic, I recommend a full flush. It's easy, without any special equipment, and takes about 30 minutes or less. DO NOT use a "power flush" machine, Allison warns they will damage the tranny. Passive flush machines are OK. You'll need about 20 qts. ATF.

[gary_lucas]

If you do a change to synthetic, I recommend a full flush. It's easy, without any special equipment, and takes about 30 minutes or less. DO NOT use a "power flush" machine, Allison warns they will damage the tranny. Passive flush machines are OK. You'll need about 20 qts. ATF.

Gotcha, thanks again.

Unrelated, I killed both batteries. dash mounted lightswitch for lights on the bar on the front of the truck.. Whacked it with my knee and didn't notice.

I had BCAA jump the truck this morning, couldn't do it with our 4runner and boost pack.

2 questions.
1) How do I get the batteries out to bring em upstairs and charge them.
2) Anything I can do differently to get the truck boosted off the 4runner, our boost cables are probably too thin of a gauge... They got pretty warm and still didn't get the truck to turn over.

I'm probably going to get enough extension cord to run a charger in our parking spot and charge the batteries one after another tonite.

Hoping the truck starts to get home this eve :)

[DmaxMaverick]

I recommend charging with batteries in the truck, both at the same time (just connect the charger to the "jump" post, or one battery). This prevents an "unbalanced" charge, which can cause future issues. Not really an issue with new batteries, but older batteries (more than a year in use) tend to be more sensitive to balance. If you have a 10-20 amp charger, it will charge dead batteries enough overnight (~10 hours) for a good morning start. The alternator will top them off while driving.

If you must charge out of the truck, it isn't that difficult. Remove BOTH ground terminals from the batteries, then remove the positive cables. At the base of the batteries, is a block with a bolt through it. This secures the batteries in place. Loosen the bolt (you don't have to completely remove it) until the block is loose enough to move out of the ledge on the battery, then lift the battery out. When you charge the batteries, and have only one charger, use your jumper cables (cheapy small cables are fine) to connect them parallel (Batt+ to Batt+, and Batt- to Batt-), and charge both at the same time, in a well ventilated area, with the batteries NOT on a concrete floor (use cardboard, wood, etc. to insulate them, if necessary). Reinstall into the truck in reverse order.

Small cables and a relatively weak charging system (4Runner) limits you to essentially charging, with very little boost capability. If the cables get hot, they're already overloaded, and that costs juice in itself (exponentially decreasing efficiency). If your batteries are weak, bypass the glow plug cycle. Just turn the key from off to start, not waiting for the cycle to complete. The GP cycle can use up whatever remaining juice that may have been available for a start. It won't hurt anything, and should start the same as any other time, if there's sufficient power for the electronics and cranking speed. If you still need to use another vehicle for a boost, it can take a long time of idling for enough charge, or less time if the boosting vehicle is revved up for a while. Most import vehicles charge at less than 10 amps at idle (regardless of what their "rating" is), which can take several hours for enough charge to start your truck. High end import, and domestic vehicles do significantly better. Another HD truck is the best option.

[AKMark]

When jump starting a Diesel, connect the cables and let it sit with the running vehicle idling for about ten minutes before you attempt to start.

Diesel's draw more than twice the amps of gas motors and need to build up some reserve in the batteries before they'll go.

Unless you have 0 gauge wiring and another Diesel doing the jumping, that's where you sit.

4-Runner's make bad jumping vehicles. Jump boxes have to be the big ones. Little 700 amp and smaller ones are no good for Diesel applications.

[gary_lucas]

Gotcha, thank you both.

When I got in the truck to drive home today the insite was reading 13.6v when idling... And it turned over no problem.

Drove an hour to get home and it seems to be running well, I'm surprised that it picked up that much charge in just an hour of driving in the morning.

I'll put a multimeter on it in the morning and see how it's sitting. If it's still low tomorrow morning I'll throw a charger on it tomorrow evening.

I picked up 100' of extension cable so I can run a charge overnite.

Where is hte 'charging' post?

Thanks,

Gary

[DmaxMaverick]

The Charge/Jump post is on the driver/left side of the engine, a little red plastic box. The Batt+ crossover cable passes through it. It's also a good source of battery power for accessories.