Nov. 01, 2003 By Rick Sieman

It's not uncommon for the owner of a full-sized truck to get 150,000 to 200,000 or more miles out of a well-maintained V-8 engine. But, more often than not, well before the engine gets tired, the automatic trans dies. This is avoidable, if you simply do some basic auto trans maintenance.

You know that you should change your engine oil every 3,000 miles or so to ensure long life. Why then, do we take the trans for granted? Once a year. I service my truck trans and have been rewarded with trouble- free service. In fact, my old Ford F- 250 has almost 200,000 miles on the engine and the trans has never been rebuilt! It's still working smooth and slick, in spite of towing some heavy duty loads over the years.

With your vehicle safely in the air, loosen the bolts on the trans drain pan. Here's a tip. The Ford E4OD we're working on here has a torque converter drain plug, which will dump about 5 quarts of ATF before dropping the pan, making the job a bit less messy.

With the bolts removed tilt the pan forward and drain the fluid into a catch pan.

The secret? Every 12 months, I drop the trans pan, drain the trans fluid and check the pan for any tell-tale residue. Then a new trans filter is installed, and I adjust the bands. Sure, it's a messy job and you're going to have to grope around under your vehicle, but the pay-off will be extended trans life. Here's how to do the job:

  • For the intelligence impaired, we offer the following warning: When you put your rig up in the air, make sure you put hefty jack stands under the frame rails so the dumb thing doesn't fall down and crush you like a grape. While you're at it, make sure the trans fluid is not hot.
  • Get a drain pan - preferably a big one - and place it under the trans.
  • Loosen all the trans pan bolts until you can turn them with your fingers. Then remove the bolts from the front part of the pan and start tilting the pan down so the fluid has a path. If you can find a second set of hands under your rig, so much the better. This way, you can remove the bolts and your buddy can tilt the pan forward to drain the ATF with minimum splashing and dripping.
  • Remove the pan completely and inspect what's left in the bottom. If the ATF is clean, you're lucky.
  • If there's a bunch of crud in the bottom of the pan, chances are you have some real trouble brewing, and you should bolt it back up and take it to a savvy shop, and find what caused the grief.
  • If your trans fluid is clean, but has a heavy burnt smell, get thee unto a
    trans shop.
  • If you find aluminum type powder in the pan, you've got serious problems!
  • Next, remove the trans filter. Some filters are held in by a bunch of small
    bolts, while others are locked in place by a single bolt, and others are simply pressed into place and held there by a grommet, like the E4OD shown in the photos.
  • If you have a filter with a metal screen, it can be reused if there's no crud in the pan, and no debris in the metal screen, even though you're always better off playing it safe and installing a new filter.
  • If you find metal particles on the screen, or in the filter, you've parts starting to fail inside.
  • Do not re-use the paper or element type filters, no matter how clean they look.
  • Clean the pan thoroughly and remove the old gasket.
  • If the bolt holes are misshapen due to over-torquing. place the pan
    edges on a metal table and lightly hammer the metal flat. Easy does it with the hammering.
  • Adjust the bands, if applicable. Most of the GM turbo transmissions have no band adjustment provision, but the Ford and Torqueflite trannies do. Refer to your manual - or call your dealer - for torque specs. For example, the Ford A4LD trans has two bands that adjust: an overdrive and intermediate (2nd gear) band. To adjust these, back off the jam nut, screw in the adjusting bolt to 10 foot pounds, then back off 1 3/4 turns. Tighten the jam nuts back up, taking care not to move the adjuster bolt, and you've done what a savvy trans man can do, all by yourself!
  • Now fill up the trans with the recommended ATF and check the level. Make sure you get the trans warm before you accept the reading on the stick. I like to get a basic reading, drive the vehicle for a mile or two, then recheck the reading. Always check the fluid level with the engine running and the trans in PARK.
  • Do a visual check to see if you have any leaks from the pan or the new gasket.

Remove the trans filter. In this E4OD, it just pops out. On others, bolts hold it in place.

Surprise! We found what caused this trans to go bad. When the trans was last serviced the original holding grommet was left in, and when the new filter/grommet was installed, the filter sat too low in the drain pan, and badly restricted the fluid flow.

Check the trans pan for crud. We found a lot of gunk in this particular pan.

Also check the fluid for aluminum particles. With Ford products, any aluminum powder is bad news. With GM products, some aluminum powder is normal.

The old smell test lets you know if the trans fluid has run hot. A burnt, foul smell is a dead giveaway.

Remove the old pan gasket and do not reuse it.

Scrape the pan clean of any remaining gasket or cement. Take care not to gouge the metal.

Wash the pan until it's clean. Do not wipe the inside of the pan with a rag without air blowing it clean, a little bit of lint can clog things up inside the trans.

Lightly hammer any bent bolt holes on the pan flat for a good seal.

Install a new trans filter. Mounting instructions usually come with each filter.

Never even think about re-using an element type filter, such as this GM product.

Carefully check the screen on a metal filter for large particles. In an emergency, this type of filter can be re-used.

InInstall a fresh pan gasket (Valley Trans says not to use gasket cement.) Carefully install the pan back on the trans using proper torque specs from the manufacturers.

Adjust the band(s) on your trans. On the C6 shown here, there's one band adjustment for 2nd (intermediate) gear. Loosen the jam nut, torque the adjuster down

After filling with the correct type and amount of ATF (again, check your manual), do a quick check for fluid level.

After driving the vehicle around for afew minutes. do a final check with the engine running and the trans in PARK. Now, repeat this process every year or so, and you'll have a reliable, long lasting tranny.


Auto trans fluid is about a buck per quart, and trans filters range from $6 for some GM models, to the mid $20s for Ford products. Rebuilding a full-sized auto transmission can cost you anywhere from $700 to several thousand.

Like Greg Boehm of Valley Trans told us: 'If people changed their own trans fluid yearly, I'd be out of business!" Newsletter
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