Hello,

My girlfriend has a 2002 explorer with 200k miles on it. She got it at 80, and it is quite possible that it has never had the trans or diff fluid changed. I would want to do have a full flush done on the trans and do the diff myself. However, I have heard the horror stories about changing fluids after not having them changed in a long time and killing the trans. Do you think it is a good idea to mess with it after all this time?

 

pull the pan if it looks really ugly then you could loosen up years of crud by flushing,probally less risk if you just change fluid & filter, if not to cruddy looking then flush.

 

Just do a partial change by dropping the pan. Repeat a couple of times and you have changed most of it. The older transmissions, like my E4OD, had a torque converter drain plug to get most of it with one change. This situation may justify sending a sample of the old fluid to Blackstone.

 

If you decide to have a tranny service done, maybe consider paying the extra $$$$ to First have them drop the pan to inspect it for debris, degree & type of deposit loading. Clean the pan & change the tranny filter, as a pan drop/filter change isn't usully part of the tranny solvent flush type service. So on a mucked up tranny, the solvent flush part of the service just stirrs up pan deposits, which to be removed, have to first be strained through an already dirty tranny filter, further clogging it up.
Then any gum, varnish, or sludge in the valve body, torque converter, cooler & lines loosened but not dissolved & removed by the solvent flush part of the service, usually come loose later on, in larger pieces to muck up the valve body & cause mischief.

So if the tranny has copious depost loading, maybe consider opting out of the solvent flush part of the service & go with just the pan drop & cleaning, filter change & continue on with a full tranny fluid pumpout, without the solvent flush, so that the valve body, torque converter, cooler & lines, where most, like 1/2-2/3 of the old fluid is, will be removed. Then the new tranny fluids detergents can slooooowly soften & remove remaining gum, varnish, sludge deposits with less chance of mischief & the new filter can likely filter them without clogging.

If you want to save about $100 or more, do the pan drop, filter change & full fluid pumpout yourself.
Its not difficult at all, here is how I do it on all my vehicles with a few tweaks to make it less mesy. I do it on my Ranger 5R55E & Taurus AXODE tranny & its the proceedure Dealers used before getting their Routunda flush machines. https://www.ford-trucks.com/forums/6...-pump-out.html

More thoughts for cosideration, let us know what you find in the way of deposits & how it goes.

 

I would definitely change the filter (due to possible residual/initial wear particulates that may be floating inside) and either drain the torque converter (if so equipped with a plug) or disconnect the trans cooler line at the radiator, fill the pan with fresh fluid, my wife starts the engine and when 2-3 quarts drain into a bucket, she shuts it off, I refill the pan and repeat until the fluid is clear. In regards to filters, oem is fine, but I typically use Wix & would definitely avoid any pressure type fluid change systems.......too many potential issues on this.

 

The 02 and newer ones don't have a dipstick and you will need to pump the fluid back up into the tranny through the smaller hole in the drain plug. Replace the o ring on the drain plug also.

I used a marine lower unit pump and it takes a while to pump 4 quarts back up in there! After pumping up 4 quarts+, start up, warm up until the fluid is at 90 - 120 degrees (warm to the hand, but not too hot if you don't have a thermometer). Shift throught he gears and leave in park. Remove your pump and some fluid should leak out in to your pan - or you need to add more until it does. When it slows to a dribble, put the small plug back in and you are done.

The filters are all the same regardless of brand (wix,fram, motocraft). I think racor? makes them and must be patented or something.

I would drop the pan and change the filter first if it were me.

Good luck!

 

I would check that for sure because the 2002 explorers came with a 5R55W transmission. These transmissions have a factory defect that almost always requires a rebuild. The intermediate and overdrive band servos wear out the case where the piston shaft's go's through. The case has to be reamed and brass bushings have to be installed. Usually requires a new overdrive band as well. It would be hard to believe one of these units could go 200,000 miles with out going out. How ever if she has put 120,000 miles on it a fluid change is probably in order.