I have a 98 XLT 4.0, auto trans with 109K miles and when it's really hot outside and it's been driven when I start back up and put it into drive it sometimes takes a while to go into gear. A friend says the transmission fluid doesn't look too good and it smells. Obviously I have a transmission problem but my question is would changing the fluid do any good at all? Since the tranny is bad what harm could it do? The fluid was never changed previously.

 

Change filter with Ford only, change fluid.
Make sure the level is correct. The fluid should be between the holes on the dipstick when cold and engine off. Fluid should be on the hatch lines when at temperature.

Should be able to get plenty of more miles out of the trans. Don't put shifter in Overdrive position until at cruising speed. Use overdrive off until cruising.

 

Consider doing a pan drop, filter change & full fluid pumpout as described here & let us know what you find in the way of pan deposits, like sludge, gum, varnish, metal pieces, or pan magnet deposits & how it does after the service.
https://www.ford-trucks.com/forums/6...-pump-out.html

 

Can I do the fluid pump out or is that a garage thing

 

You do it following the clues in the link.

 

Well I finally dropped the pan...It was surprisingly clean..there was gunk stuck to the magnet...metal particles I assume...I don't know if that's a bad thing or not...

With the pan off is it okay to try any drain more out through the coolant lines or should I have done that before dropping the pan?

 

From what your describing, it sounds like you have normal pan deposits, band goo/paste on the pan magnet is normal & a light coating of clutch dust on the pan bottom is normal.

Change the filter with a quality Motorcraft/Filtran product, clean the pan inside & out with a spray cleaner, no linty wipes. If the pan gasket is ok, it can be reused. If not, Felpro makes a quality reuseable gasket, with slightly undersized holes, that we screw the pan fastners into, to hold the gasket & fastners in place & that gives us both hands free while we align the pan & get a couple of the fastners hand started to hold the pan up.

After replacing the filter & pan, follow the above posted routine for refilling the pan, disconnecting the tranny return line at the tranny cooler & idling the engine for 15-30 second periods, to pump out/flush, the valve body, torque converter, cooler & lines, one-two of qts at a time untill the listed full tranny capacity has been removed.

This proceedure is the one Dealers used before they got their Routunda flush machines, that automatically push new fluid in, as the trany pump pushes old fluid out the tranny return line. The only difference is we have to stop the engine every 15-30 seconds to pour in more fluid, so the tranny pump doesn't run dry.

With the vehicle Level & at warm idle, the tranny pump removes 1qt/15 seconds & with the vehicle Level, we can pump out 2qts/30 sec idle time, without running the pump dry.
If the vehicle isn't level, like if the front end is raised on ramps or stands, or is on a slope, most of the fluid will be toward the rear of the pan, so pump out one qt (15 second idle) at a time, so as not to run the tranny pump dry, or uncover the filter pickup & aerate the fluid.