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Transmission and towing question

G

GoBlue

NAXJA Forum User
Location
Southern MN
I have a 2000 xj 4x4 w/ 93,000 miles... auto tranny...

I moved and towed a 5x8 uhaul trailer from CO to Minnesota, pretty full and very heavy. I didnt have any experience with towing so I drove for around 300 miles with the OD on, while on the highway. As soon as I started to go on the back roads my tranny would shift erratically, so I would pull over and let it sit for a while. I did my research and drove with the OD off in 3, also checked my fluid constantly, and it didnt smell burnt, never low. The fluid is a little brown, but not too bad. Do you think I have anything to worry about? Should I change the fluid asap? Does it sound like an overheated tranny, and should I be looking for signs? Thanks!
 
define "shift erratically"
 
There were some rolling hills, and it would try to guess which gear to be in on the way up sometimes. Maybe once or twice it would just go nuts to 4-4500 rpm, 2nd gear I guess. Nothing serious I would think.
 
well if you were in a hilly area the transmission was searching for what gear it needed to be in. you did the right thing by taking the trans out of O.D.when your towing a heavy load and with a trailer you want the engine to do the work. when in overdrive trying to tow and the trans shifts up and down then your making the trans do the work. a trans will burn up that way.yes i would definitely change the fluid. those AW4 transmissions are pretty bullet proof. but like anything else if abused severely they will fail.
 
When the AW4 is in 2, 3 and 4, it could and would go into OD. There is nothing to operator could do to prevent it without some form of modification to the TCM like adding an OD lock out switch.

And by-the-way, the AW4 need to be in OD to be able to cool itself properly. Something about the torque converter and pumping oil at pressure and slipping more. [AW4 guru input here]......................................

I would however manually shift into 3 when ascending or descending hills. This would preventing the gear hunting that you experenced going up the hill and add a bit of engine (every little bit helps) breaking going down.
 
4th is OD. The way to keep it out of OD, is to put the shifter in 3. The trans will not shift into OD with the lever in 1-2, or 3. OD is only available when OD is selected. The transmission does not need to be in OD in order to cool.

From the Owner's manual, tips for towing.

Cooling System Tips - Trailer Towing
To reduce potential for engine and transmission overheating, take the following actions:

City Traffic - When stopped, put the transmission in neutral and increase engine idle speed.

Highway driving - Reduce speed.

Air Conditioning - Turn off temporarily.

See Cooling System Operating Information in the Service and Maintenance section of this manual for more information.

To reduce potential for automatic transmission overheating, shift to 3 (Drive 3) when driving in hilly areas or 1-2 (Drive 1-2) on more severe grades. Move the shift lever to the next lower position to eliminate excessive transmission shifting. This action will also reduce the possibility of transmission overheating and provide better engine braking.

NOTE: If your vehicle has an automatic transmission and you tow a trailer frequently, especially in hilly country or when the outdoor temperature is high, we recommend that you do one or both of the following:

Change the transmission fluid at 15,000 mile intervals.

If your vehicle is not already equipped with an oil-to-air transmission cooler, have such a cooler installed on your vehicle.
Click to expand...

edit- and yes, I would change the fluid. It sounds like you may have overheated the fluid, although beyond changing the fluid, I wouldn't worry a great deal about it, provided that it behaves normally.
 
Last edited:
hubs97xj said:
4th is OD. The way to keep it out of OD, is to put the shifter in 3. The trans will not shift into OD with the lever in 1-2, or 3. OD is only available when OD is selected. The transmission does not need to be in OD in order to cool.
Click to expand...

Are you sure you are refering to the AW4 that is in the XJs?

What is the source of your information?
 
hubs97xj said:
The FSM and the ATSG AW4 manual, and this thread and anything else about the AW4 you can find.
Click to expand...

You need to do some research again. Years ago, I had a home made OD and second gear over ride, I proved to myself that the AW4 actually have OD in 2, 3 and 4. It is easy for you to check the 3 OD if you have the AW4 in your XJ. Just shift it into 3 and drive it while paying attention to the RPM (and I assumeyour XJ have a RPM guage)vary the speed and aslo hit the break pedal lightly while maintaining a steady pressure on the gas pedal.

When the OD is off, the clutches slip more. Slipping causes friction. Friction generates heat. :conceited
 
techno1154 said:
When the OD is off, the clutches slip more. Slipping causes friction. Friction generates heat. :conceited
Click to expand...

If your clutch packs are slipping at any time other than during a gear change, your trans is bunk. My statement doesn't include clutches and bands "freewheeling" when they are intended to in a particular gear with no hydraulic pressure applied to them.

Many transmissions will divert flow away from the cooler in OD in order to improve mileage figures. Valvebody mods can correct this. Direct drive is the only way to keep the rpms up and the tranny pump circulating oil properly with heavy loads. Besides, direct drive in the AW4 is a straight shot through the transmission, without the OD planetaries increasing the output shaft rpm "over-drive" and adding internal stress within the case.
 
Last edited:
techno1154 said:
You need to do some research again. Years ago, I had a home made OD and second gear over ride, I proved to myself that the AW4 actually have OD in 2, 3 and 4. It is easy for you to check the 3 OD if you have the AW4 in your XJ. Just shift it into 3 and drive it while paying attention to the RPM (and I assumeyour XJ have a RPM guage)vary the speed and aslo hit the break pedal lightly while maintaining a steady pressure on the gas pedal.

When the OD is off, the clutches slip more. Slipping causes friction. Friction generates heat. :conceited
Click to expand...

yer funny. you are confusing Overdrive which is another gear, with the lockup torque convertor.
 
98stocker said:
yer funny. you are confusing Overdrive which is another gear, with the lockup torque convertor.
Click to expand...
&^^^

that is the convertor locking up. Same as my ranger's original A4LD and now it's AOD. You can sense "5" distinct rpm changes(1,2,3,3 w/lockup,OD), but there are only "4" gears (1,2,3,OD)
 
Good argument here, but thanks so much for the info. When I change the fluid in the tranny I need to make sure to not flush it, just change it, and also change the torque converter fluid also right?
 
Just to clarify if it's not been made plain here already: According to the factory service manuals, etc. the AW4 WILL lock its torque converter in third gear.

I quote from the 9f FSM: "Torque converter clutch engagement occurs in second gear in 1-2 position;third gear in 3 position and third and fourth gear in D position."

It's been years since I drove an AW4, but when I had an 87 with the power/comfort switch, I could make it wait until it hit fourth to lock, lock in third and shift into fourth still locked, or lock in third, unlock, shift and lock again, depending oh how I pushed the throttle.

Edit: I see Carbon beat me to it a bit.
 
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