722.6 transmission fluid change question

[300EE320]

I have a 2002 E430 with the 722.6 transmission. I just changed the fluid. After draining and removing the pan, I went to drain the torque converter, and this one does not have a drain bolt! I pulled both rubber covers and turned the engine over about 5 times before I finally convinced myself that it doesn't have a drain plug.

Have others experienced this?

I did open up the cooler lines under the radiator and got an extra .5 liter out. So, I was able to replace 4 quarts, the filter and clean out the pan, which really needed it. So, I'm glad I did the work, but dissappointed that I couldn't do the complete change.

[Hirnbeiss]

The later models don't have the drain plug. One way to change the fluid out is via the cooler line, but you stop and start the engine a few times, pumping a quart out at a time and adding one in via the fill tube until you have added your 10 quarts.
I'm not sure if this is an "approved" method for MB, but it is for some other brands.

[300EE320]

Thanks - at least I'm not crazy! I am thinking that with the next oil change, I'll use the liquivac to suck out the fluid from the pan and change a few more quarts. At this rate, it'll never be a full change of fresh fluid, but the old fluid that came out seemed fine, just dirty.

[300EE320]

Any other input on how to completely change the fluid on this model? How would the dealer do the job?

thanks!

[TimFreeh]

Originally Posted by 300EE320

Any other input on how to completely change the fluid on this model? How would the dealer do the job?

thanks!

I haven't seen it first hand but according to my local person behind the parts counter the dealer has a process that hooks into the oil cooler lines to get new fluid into the system as the old fluid is drawn out.

This seems less than ideal to me since it seems like the new fluid would mix with the old fluid in the sump before all the old fluid was drawn out through the oil cooler lines.

I suspect replacing half the fluid at 30K intervals would work OK, at least that's what I've been doing on my 722.6 equipped cars that don't have drain plugs and so far I've had no transmission problems at all - and several of my cars have near 200K miles on the original transmissions.

I know lots of people have had 722.6 problems but mine (knock on wood) have operated flawlessly. It's a great transmission.

[300EE320]

Thanks - that is an interesting approach. I cleaned a lot of sediment out of the pan, which would be missed if it was just a fluid change. I can't imagine pumping that $15/qt fluid through as if it was a brake fluid flush. I wondered if the front pump on the trans would pump out the fluid even if it was sucking air, until the torque converter was empty.

I'm kind of surprised that a pro tech hasn't chimed in since this is probably becoming one of the more popular DIY jobs as these cars age.

[Hirnbeiss]

[QUOTE=300EE320;2360757]Thanks - that is an interesting approach. I cleaned a lot of sediment out of the pan, which would be missed if it was just a fluid change. I can't imagine pumping that $15/qt fluid through as if it was a brake fluid flush. I wondered if the front pump on the trans would pump out the fluid even if it was sucking air, until the torque converter was empty.
QUOTE]

The correct method mentioned above (for the Ford Windstar/Taurus) is to drop the pan, change the filter, reinstall pan & refill fluid. Then pull the pump discharge line to the cooler, start the car for maybe 45 seconds (monitoring how much you pump out), stop the car then add the same amount of new fluid back in. The pump never gets dry, and the total fluid used was about 13 quarts.