Changing the Transmission Fluid


Sep 22, 2023
Harriman, TN
Vehicle Details
2x 1996 Cougars, 1997 Tbird 4.6's all.
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To change the transmission fluid, I recommend dropping the pan on the bottom; this gives you the opportunity to see how much wear has happened, either since the last change, or ever. :)

You will need: 6 to 12 quarts of Mercon V transmission fluid A filter for sameyear trans. How much fluid depends on how far you go.
You will only use 12 quarts if you do the pan, tc, and drop the vb. If you do the jmod, you will need 12.
Optional parts: Dorman pan with drain plug
New style 1-2 accumulator
Brown 1-2 spring(very optional, barks 1-2)
An oil drain pan at the front edge of the trans pan, pull the 4 front bolts. loosen all bolts on the pan 2 turns. Starting at the front of the pan start removing bolts in pairs, left side right side, alternating sides. Each time you pull a pair out, give all the other bolts one turn At some point pan will droop down, dumping mercon (Hopefully) into the pan. :) Good luck, this is the 'mercon shower' these are famed for.

Keep going until the pan drops.
Set the pan aside for now.
Pull the filter straight down using both hands. Make sure the orange rubber seal is not in the filter bore. There are pix in the Jmod article. Inspect the condition of the wires, looking for missing insulation, etc.
Inspect the pan: the black stuff is friction and metal worn off the plates in the trans. The thing with black 'hair' is a magnet there to collect it. carefully pull it off the pan, and clean it off with a clean lint free rag. Wipe the pan out.
If there's a white 'top' looking thing, it's the "Secret magic mystery prize!" It's a seal the factory used, and it means the trans has never had the filter changed.
Pull off the rubber cover below the torque converter, and turn the engine until you see the drain plug.
Drain it into the pan, this is about 4 quarts of fluid.
Put the drain plug back in.
This is the point you do the Jmod, if you're doing that, or change the 1-2 accumulator. Put in the filter, noting the pickup and pan dimple. Spending the $20 for the dorman pan means you get to skip the droopy part. If you get the dorman pan, swap your magnet over.
Put the clean pan back in, making sure the flange didn't bend during the drooping part. a hammer and the garage floor will flatten it out if it did.
Reuse the original gasket, you don't need sealer.
Torque all bolts to 20ft-lbs; don't overtighten.
Verify all bolts; add 4 qts of fluid, and start the engine. add 1 quart, run the trans thru the gears with the shifter, while letting it idle in neutral.
Check fluid level
add 1/2 qt at a time until it reaches the full cold line.
Drive it around the block, let it shift thru the gears.
From a redlight, shift it manually thru the gears;
Recheck the fluid level, it should now be at "full warm".
You're done. I write it down in the car's logbook,with the mileage, and tape the receipts in it. :)
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Even after all these years of working on 4r70w transmissions, i still can't believe Ford didn't put a drain plug in the pan. Such a hassle. I used to use the U Haul pans, but now i use the Dorman pan which seems to be the same.
Good write up!
You can also get the majority of the pan empty by draining thought the radiator pipe.
Just don’t let the car run once the fluid stops flowing.
Just don’t let the car run once the fluid stops flowing.

Not an issue if you have a helper fill fluid through the dipstick tube simultaneously.

But now we're in the realm of flush rather than  change.

My process:
  1. Siphon fluid from pan
  2. Refill pan
  3. Disconnect line to radiator cooler; attach vinyl tube to this line and lead to waste fluid container
  4. Position helper with fresh fluid at dipstick tube
  5. Start engine; monitor waste fluid color while helper adds fresh fluid; shift through gears
  6. Stop engine when color turns clear
  7. Reconnect cooler line
  8. Check fluid level

Mind you, I only did this once since I bought the car, and at the time I didn't own ramps, so I had no way of getting under the car.

The fluid change process described above is better in that it includes pan cleaning and filter change.

Ultimately, I think my preferred method would be a combination of both: pan cleaning and filter change followed by flush through the cooler line.

I'm not convinced that a torque converter drain is needed at all since Ford removed the torque converter drain plug on later 4R70Ws.
Someone asked on the old place, so I wrote that and sent them here.
Actually, it was You!
This is the pan:
30 bux, look around price varies a lot.Factory recommends replacing the fluid every 25k miles in rough duty, Which my driving is.

The problem using the pump to empty it is that it runs dry for a few seconds, and is hard on the seals. At the age of these trans,they do not need that.You need to change the filter, and inspect the magnet.
If you install a pan with a drain plug, there's no risk, and it removes just as much fluid. Pumping it out does not empty the tc. And it needs the vb dropped to get it all out.
Those are 2 ways to Avoiding the bath initially. Then replace with the Dorman pan.
If you cover yourself with trans fluid, it's on you. (literally, in 2 senses.) Taking the bolts out in the sequence I posted, will let the front of the pan down slowly enough to pour slowly off the front edge if the pan. By the time you drop the pan, there's a half pint of fluid in it.
I've accidently rolled thru some that spilled, and dropped my ponytail into the pan, but never showered.
I’ve started trying my dreads up in bun to avoid those unfortunate circumstances. I hate man buns, but it’s beneficial when wrenching.
Get a chunk of hair ripped out, it will make you tie it up, lol. Wasn't me; girl in shop class.She got a 1" square chunk ripped out by a buffer wheel. Most blood I've ever seen, that wasn't mine, lol.

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