what is the best way to flush tranny fluid?

what is the best way to change tranny fluid? one of those flush/fill places or manually dropping the tranny pan and changing the fluid/gasket?

your opinion matters.

thanks

 

We've had some heated discussions on the matter in the past. Here's my $.02 worth: I have never had a tranny flush done on any of my vehicles including my wrecker which got something on the order of 280,000 miles on the last tranny. I DO change fluid much more often than what is called for - every 10k miles with a new filter every other change. On my personal vehicles I do service every 25k miles (Toy Camry - screen, no replaceable filter). Wife's last vehicle was still going strong at 175k miles.

If you want the absolute in tranny service, that would be a machine flush followed by a pan drop (to clean out the bottom of the pan itself plus clean the magnet, if there is one) and filter change. IMHO, for most applications it is massive overkill, although it is a profit center for the garage.

Year/make/model/mileage?

 

thanks for info

i didn't include my vehicle info because i wanted people's opinion based on the concept of "tranny flushes" rather than on the type of vehicle but...

2003
dodge grand carvan
115K

so, i should drop the pan, clean it out and replace gasket and filter and put in new fluid?

how do you hold the gasket in place while bolting back on the pan?

thanks again

 

I don't know how true this is but something to think about. I read in Family Handyman magazine that if the transmission hasn't been flushed before, with 115k on it, you can do more harm than good.

According to the article, putting in all new fluid will loosen deposits then these little pieces will travel around and plug things up.

Just something I've read.


Baldwin

 

I agree with Baldwin. If it's never been flushed, just do a fluid and filter change.

I'm trying to remember about the gasket...seems like the last one I did had some locating studs and holes in the pan, to keep everything lined up. Could be wrong.

 

I would not do a flush either. I was at my transmission guy's shop and he was on the phone with a customer and I overheard him say that he doesn't recommend a flush on older cars--more trouble than good. I do not know about new cars. My new kia has a screen, so no filter, so no dropping the pan--drain and fill only. Make sure your car gets the correct fluid back in it.

On a car that requires a filter change, I take the new filter and trace the outine of it, along with the bolt holes on a piece of paper/cardboard etc. . .

Then as I take out each bolt that holds the filter I put it at the hole on the tracing that that specific bolt corresponds to in the engine. (I have an Altima and it seems every filter bolt is a different length!).

I also clean out the pan with brake parts cleaner--leaves no film and dries quickly. (Put the small red hose into the spray cap and it's great for killing wasps too!)

As for holding the gasket, I use some gasket sealer on the pan's edge, stick on the gasket(use rubber not a cork-based gasket--have had leaks with cork!) and use the pan bolts to line up the holes, then gently push the gasket so the sealer holds it in place. Put sealer on the car and put the pan back on. Repair books should have a bolt tightening pattern to follow for the pan reinstallation.


Have fun!

 

Transmission Fluid Exchange

For those interested, here's the fluid change method I use on all my cars that don't have a torque converter drain:

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.

 

Trim adhesive also works good on holding the gasket. I think the stuff I have is a 3M product. Kind of a yellow goo in a tube. Also, some newer gaskets come with several of the bolt holes intentionally undersized; you put the gasket in place and stick the bolts in those holes. The undersize holes hold the bolts in place and the bolts hold the gasket in place.