Trans flush or fluid/filter change?

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Jan 29, 2008
Brickerville, PA
I've got an 08 Jeep Wrangler with the 42RFE in it, and was wondering if I can get away with just doing a fluid/filter change myself, or should I take it somewhere to have the whole thing flushed? I'd like to have it flushed everytime, but that gets pretty expensive, and I'm afraid to take it just anywhere to have it done since it requires ATF+4, which isn't the easiest to find. But I'm not sure it I wanna just stick with fluid/filter changes for the life of it since these tranny's have a reputation of not being the most reliable things in the world, nore the longest lasting. How much is actually left over in the torque converter and passages when just dropping the pan and filter?
About 8 quarts is left over.

Flush it yourself. Use a piece of tubing connected to the cooler line. Start the engine and drain it till air bubbles show up in the line. Shut off the engine. Add the pan capacity of ATF (usually around 4 quarts). Do this till clean fluid comes out.

I always use 16 quarts of ATF because it always ends up with a clean transmission.

I have dropped pans, replaced filters, etc etc etc

All I work on now are Aisin Warner boxes, they have no filters, and even if they did, they would still just get flushed.
If your fluid is repetitively clean now, change the filter and the fluid that comes out... Don't worry about the rest. The flush is more for over-used fluid IMO.
Well, I'd drain the pan with the cooler line before dropping it. Much less messy.

There's no way you can take it anywhere for just a pan drop and filter change and end up spending less than you will for a new filter(s) and enough ATF to fully flush it.

Your fluid is pretty new SteveC's comments have merit.
the fluid and filter change I can do myself no problem. I just don't have the machine to do the tranny flush myself, or I would.
You don't need a machine, just a length of clear hose. Here's the fluid change method I use on all my cars that don't have a torque converter drain:

Transmission Fluid Exchange

1. Pull the transmission dipstick (located near the firewall in most cars). Fresh fluid is translucent and cherry red. Some darkening is normal, but if it is reddish brown or mustard color and smells like burnt varnish, it is worn out.

2. Make sure the fluid is warm.

3. For pans that don't have drain plugs, remove all pan bolts except for the corners. Remove the bolt from the lowest corner, then loosen the other corner bolts a turn or two. Carefully pry the pan to break the gasket seal at the lowest corner. Drain mostly from this corner. With good technique you can avoid or at least minimize the red bath.

4. Remove pan. Inspect the pan before cleaning. A small amount of fine grey clutch dust is normal. However, if you find metal shavings, there has been transmission damage. Remove all old gasket material. Clean the pan and magnet with solvent and wipe dry so there is no harmful residue. Shop air can be used to clean the magnet. Hammer back any pan damage from previous overtightening.

5. (Optional) Drill hole in pan at low point and install a drain kit available from most auto supply houses. Make sure the kit protruding inside the pan doesn't interfere with anything on the transmission.

6. Replace filter. If it’s a metal screen filter, it can likely be cleaned and reused.

7. Position gasket on pan. Some gaskets have four holes slightly smaller than the rest to allow four bolts through the pan and through these smaller holes to hold the four bolts and gasket in place.

8. Hand tighten pan bolts in a criss-cross pattern. After that, use a torque wrench to tighten bolts to proper ft-lbs as per manufacturer.

9. Refill the transmission using only the amount shown as “refill capacity” in the owners manual (or an equal amount that was drained), using the type of fluid specified for the vehicle.

10. You now have replaced the trans fluid and filter according to manufacturer’s requirements. Fluid is changed in the pan only.

You can stop here and go to Step 17 if you just wanted a regular drop-the-pan fluid change. For a complete exchange of the fluid (including transmission body and torquer converter) continue with the next steps.

11. Obtain the total system capacity of the vehicle from the manufacturer. Have this amount - plus a bit more - of fluid readily available.

12. Disconnect the oil cooler line from the oil cooler. Tickle the ignition to find the flow direction. Direct the stream of fluid toward a receptacle. It is better to use a clear length of hose with a shoplight laying next to it so you can see when all the old fluid has left the system.

13. Start the engine, let it idle to pump out old trans fluid until you start seeing air bubbles.

14. Stop the engine. Refill transmission through fill tube with fresh fluid - same amount as pumped out (usually about 2-3 quarts).

15. When either the fluid color brightens or the total capacity has been replaced, shut the engine off and re-attach the oil cooler line. All trans fluid has now been changed.

16. Button everything back up. Clean up the mess.

17. Recheck the fluid level. With the car on level ground, set the parking brake and the transmission in “Park” or “Neutral.” Let the engine idle for a few minutes. Shift the transmission through all detents, pausing momentarily at each position, before returning the lever to “Park” or “Neutral.” Check the fluid level again and check for leaks. Refill fluid so it is slightly undercharged. This way it can be properly checked and topped off after a long drive.
Kestas, Awesome description...
If your drain pan has no drain plug and you don't want to drop the pan, then consider starting the flush by running the engine until you see air bubbles in the line and then add ATF and start the flush. By doing this you will significantly cut down on mixing of old and new ATF (but a drain first is even better).
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