ATF fluid change help

[seven_magnum]

I need some help performing my first ATF fluid change on my 96 chevy pickup. I have plenty of Valvoline Maxlife ATF fluid and a filter kit for the truck. (Pro-King if it matters)The fluid has 35k on it now, and still looks ok and doesn't smell burnt but it isn't new either... Anyhow, would I be best to drop the pan, change the filter and refill the fluid that was drained? Or should I attempt to perform a complete fluid change as described by Amsoil. I believe that required removing a line and running the engine while someone dumped fluid in the dip stick tube at the same rate it was pumped out. I am leaning toward the later to change the fluid in the torque converter, but I have never performed this type of change and am concerned I may mess something up. My main concern is how fast do you add the fluid? I really have no idea how fast it may pump out of there, and I don't want to be surprised! Should I try this and learn or would I be better off to drain the pan and let the new and old fluid mix. I thank you for your advice!

 

[Eddie]

At 35 K miles I would just do a pan drop & refill, then every 30 K or so.

 

[pbm]

Originally Posted By: Eddie
At 35 K miles I would just do a pan drop & refill, then every 30 K or so.


Ditto.

My GM (Buick) doesn't have a drain plug so it can get messy dropping the pan. What I've started doing is buying approx. 7 feet of 3/8" clear tubing and putting it down the dipstick tube and siphoning the fluid out. When I drop the pan it is almost empty and far easier to deal with.

 

[Kestas]

Transmission Fluid Exchange

Written below is the fluid change method I use on all my cars that don't have a torque converter drain. Use shortcuts as appropriate.

1. Pull the transmission dipstick. 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. 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. Some rubber gaskets are reusable. 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.

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 torque 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.

 

[seven_magnum]

Ok, it sounds easy enough to change the fluid in the torque converter as well. My question is, can I change the pan fluid and filter, refill the fluid lost from the pan, disconnect the oil cooler line and start my engine until it stops pumping fluid or I get air bubbles? Then I can refill the pan and repeat until the fluid looks like new? I am just concerned something may happen when I run the torque converter out of fluid. If this is not an issue, I think this will be my best bet, and easiest to do by myself. I won't need to find help to add the fluid as it is drained. I thank you for your help!

 

[Kestas]

For the first question... the answer is yes. In fact the procedure I wrote indicates that you first drop the pan, clean it out, and refill the lost fluid. Then you continue with the cooler line part of it.

Don't worry about the bubbles part of it. Though it's run out of fluid to pump out, the transmission is still wet with lubricant. It's not the torque converter that runs out of fluid, it's the pan. There have been no reports of problems doing it this way. In fact, companies like AutoRx recommend doing it the same way.