Changing transmission fluid on 1991 4l Ranger auto

[alpac]

Hi guys,
I have not posted for a while. I still have my reliable 1991 4.0L Ranger. The truck has now 160k miles on it and drives great. I fixed a lot of things right after I bought it and then have been doing regular maintenance since. After the first few big fixes (master cylinder, breaks ad break lines, A/C). The truck has been mostly trouble free since. I would like to change the tranny fluid as it looks dark and may even be the original. Changing the fluid on high mileage vehicle may sometime generate transmission problems as it can disturb deposits that have formed over the years. That is why on cars with old ATF, instead of flushing the ATF I replace it by draining the torque converter, then filling up back the same quantity of new fluid, drive for 2mns and repeat the operation until the fluid that drains is clear enough. It is a pretty long process but I have had very good results with this approach. I don't see any drain plug on the torque converter of the Ranger so my question for you guys is what is the best way to replace the ATF on an old Ranger with old ATF in it? I believe the right ATF is Mercon but NOT Mercon V, is this correct?
Thanks
Al

 

[alpac]

I forgot to add that my truck is 2wd.

Hi guys,
I have not posted for a while. I still have my reliable 1991 4.0L Ranger. The truck has now 160k miles on it and drives great. I fixed a lot of things right after I bought it and then have been doing regular maintenance since. After the first few big fixes (master cylinder, breaks ad break lines, A/C). The truck has been mostly trouble free since. I would like to change the tranny fluid as it looks dark and may even be the original. Changing the fluid on high mileage vehicle may sometime generate transmission problems as it can disturb deposits that have formed over the years. That is why on cars with old ATF, instead of flushing the ATF I replace it by draining the torque converter, then filling up back the same quantity of new fluid, drive for 2mns and repeat the operation until the fluid that drains is clear enough. It is a pretty long process but I have had very good results with this approach. I don't see any drain plug on the torque converter of the Ranger so my question for you guys is what is the best way to replace the ATF on an old Ranger with old ATF in it? I believe the right ATF is Mercon but NOT Mercon V, is this correct?
Thanks
Al

 

[Sasquatch_Ryda]

There is no torque drain on them. Best way to change all the fluid is to either do it through the cooler lines, or pay to get it flushed (fluid exchange)

A flush is NOT going to harm a transmission that is functioning properly period. That is an old wives tale started by people who take their vehicles in for a trans flush because they are experiencing shifting/transmission concerns already and are expecting a flush to be some miracle fix for it.

Yes your 91 will have just plain old Mercon in it.

 

[exbass94]

Flushing the ATF accomplishes the exact same thing except much easier and faster. A flush does NOT dislodge any gunk or deposits. You can do a flush yourself by disconnecting one of the cooler lines, start the engine and let the transmission pump out a few quarts of fluid. Shut engine off, top off the trans, and repeat until all fluid is changed. (This is exactly what repair shops do when they do a flush, except they have a machine that automatically refills the trans as it gets pumped out.)

You can use regular Mercon OR Mercon V. Mercon V supersedes regular Mercon and is fully compatible.

 

[tx3nc]

My mechanic did the following with my F-150.
He dropped the oil pan and collected the fluid in a clean container.
Replaced the trans filter.
Then he refilled the trans with the oil he had removed.
He topped it off with one quart of atf to replace what had spilled.
Then he connected his flushing machine and flushed the trans fluid out with new.

The trans flushing machine is a little different than described above. It connects into a trans cooler line. As old fluid is pumped out of the line by the trans pump and into the machine, the machine pumps new fluid into the trans via the return line to the trans. The old and new fluid never intermingle. The methods described above will mix old and new fluid and dilute the old stuff until it looks good. Nothing wrong with that method that I know of. But it probably uses more fluid than the flushing machine does.

 

[alpac]

Thanks for the responses folks. I did an ATF flush via the cooling lines in my Volvo S60 sometime ago so I do know the process. I am glad the Ranger enables to do the same thing. Which of the 2 cooling line hoses should I disconnect? the one just below the radiator filling cap or the next one below? Since it depends which way the ATF flows thru these lines I want to be sure that I disconnect the right one before making a mess in my garage
Al

 

[Sasquatch_Ryda]

The top line is the output from the pump.

 

[alpac]

The top line is the output from the pump.

THANKS