Did a fluid change on my 04 Expedition yesterday. 164k on the original fluid. It looked OK on the dipstick, with no bad smell, but in the pan it was pretty dark. There was some fine ferrous sludge on the magnet and a good number of fine bright non ferrous flecks that I could see in the sunlight. The tranny was functioning fine, so I am hopeful that things will be OK….
I searched many times, in multiple sites about how to do this swap, with mixed findings and a lot of contradictions, so I am writing this up as a bit of a “how to”, according to me at least. YMMV
Tranny is a 4R75W, though some expys got 4R70W that year. They do not have a torque convertor drain plug. Those trannys are substantially the same, but some (all?) got a thermostatic block which sits outside the tranny. This block regulates the flow of oil to the radiator and accessory transmission cooler. It precludes doing a conventional power flush by the dealer, since taping into the lines forward of the thermostatic block does not allow for flow through the tranny, unless the oil temp is over 140.
I have read that some shops CUT the lines. Personally, I’d think that is poor idea. Although, it might take effort, the therm block has threaded fittings. To get the maneuverability to remove the lines from the tranny to the therm block, you’ll need to remove the anti-rattle clips that hold the lines together, and also slip the lines out of a holder clip one place forward of the block. Then, remove the TOP line on the rear of the block, which is actually the line from the bottom outlet on the tranny. That is the pressure line. You’ll need flare nut wrenches for this, and a vice grips to hold the block so that you do not twist/stress the lines when you unthread the nut.
I tried also to remove the return line (top one into tranny) and flow fluid back in that way. It did not take, even with the jug three feet up and engine running. Must need some pressure. I would not bother with that.
Then attach a 6-10 foot length of clear 3/8” I.D. hose and secure with a hose clamp. Do not over tighten, lest you damage the end of the hard line. It is not a traditional flare or AN fitting, but some sort of flare that takes an o ring. Don’t lose that, or bugger up the flare.
Now, the problem I faced is that the transmission pumps out the oil much faster than I could pour in back in. (as noted above, I hoped to get it to take via the return line, but no workie..) I had dropped the pan, which removes about 5 quarts there, and replaced the filter. I put 5 quarts clean fluid (I used Castrol Mercon V cause I got it cheap) back in.
I talked my lovely assistant (wife) into starting the expy and cycling it thought the range while I was pouring like a madman. But it blew bubbles at about 10 quarts (5 quarts in pan, plus 5 I was pouring in). If it draws air, its not flushing the old fluid out a “cleanly” so this was a mistake. My recommendation for the next person would be to get as large a funnel as will fit in the fill tube, with no restrictions. Mine has a screen and a valve and the fluid just would not flow well. Make sure the fluid is warm too, that will help. I had to have her kill the engine while I cought up with pouring.
In the end, the fluid went clear in the line to my waste bucket, indicating that most of the old fluid was flushed out.
I also put a drain plug in the pan, so that the mess of dropping the pan is less in the future, should I even have to do it again. I plan to drain the pan and top with fresh fluid every 20k or so from here on out….
Other observations/tips: The filter is NOT wire mesh, but a sort of felt. I do NOT think that a backflush at a shop or dealer is a good idea at ALL. Needs replaced. My filter just fell off (with a big annoying splash of fluid in my face) when I dropped the pan. There was a seal on the filter neck which stayed in the tranny. I had to pull that out with a little gasket hook. The pan gasket is re-useable, but do NOT over tighten the 14 pan bolts. 10 ft/lbs is factory manual. Otherwise you will distort the pan and it will leak.
I did not bother to remove the lines going to the cooler/radiator. I figured that pint or so of oil would not do too much harm. If I were dealing with a tranny that had shot [censored] and threw fileings into the oil, then flushing those lines and the cooler would be important too.
I searched many times, in multiple sites about how to do this swap, with mixed findings and a lot of contradictions, so I am writing this up as a bit of a “how to”, according to me at least. YMMV
Tranny is a 4R75W, though some expys got 4R70W that year. They do not have a torque convertor drain plug. Those trannys are substantially the same, but some (all?) got a thermostatic block which sits outside the tranny. This block regulates the flow of oil to the radiator and accessory transmission cooler. It precludes doing a conventional power flush by the dealer, since taping into the lines forward of the thermostatic block does not allow for flow through the tranny, unless the oil temp is over 140.
I have read that some shops CUT the lines. Personally, I’d think that is poor idea. Although, it might take effort, the therm block has threaded fittings. To get the maneuverability to remove the lines from the tranny to the therm block, you’ll need to remove the anti-rattle clips that hold the lines together, and also slip the lines out of a holder clip one place forward of the block. Then, remove the TOP line on the rear of the block, which is actually the line from the bottom outlet on the tranny. That is the pressure line. You’ll need flare nut wrenches for this, and a vice grips to hold the block so that you do not twist/stress the lines when you unthread the nut.
I tried also to remove the return line (top one into tranny) and flow fluid back in that way. It did not take, even with the jug three feet up and engine running. Must need some pressure. I would not bother with that.
Then attach a 6-10 foot length of clear 3/8” I.D. hose and secure with a hose clamp. Do not over tighten, lest you damage the end of the hard line. It is not a traditional flare or AN fitting, but some sort of flare that takes an o ring. Don’t lose that, or bugger up the flare.
Now, the problem I faced is that the transmission pumps out the oil much faster than I could pour in back in. (as noted above, I hoped to get it to take via the return line, but no workie..) I had dropped the pan, which removes about 5 quarts there, and replaced the filter. I put 5 quarts clean fluid (I used Castrol Mercon V cause I got it cheap) back in.
I talked my lovely assistant (wife) into starting the expy and cycling it thought the range while I was pouring like a madman. But it blew bubbles at about 10 quarts (5 quarts in pan, plus 5 I was pouring in). If it draws air, its not flushing the old fluid out a “cleanly” so this was a mistake. My recommendation for the next person would be to get as large a funnel as will fit in the fill tube, with no restrictions. Mine has a screen and a valve and the fluid just would not flow well. Make sure the fluid is warm too, that will help. I had to have her kill the engine while I cought up with pouring.
In the end, the fluid went clear in the line to my waste bucket, indicating that most of the old fluid was flushed out.
I also put a drain plug in the pan, so that the mess of dropping the pan is less in the future, should I even have to do it again. I plan to drain the pan and top with fresh fluid every 20k or so from here on out….
Other observations/tips: The filter is NOT wire mesh, but a sort of felt. I do NOT think that a backflush at a shop or dealer is a good idea at ALL. Needs replaced. My filter just fell off (with a big annoying splash of fluid in my face) when I dropped the pan. There was a seal on the filter neck which stayed in the tranny. I had to pull that out with a little gasket hook. The pan gasket is re-useable, but do NOT over tighten the 14 pan bolts. 10 ft/lbs is factory manual. Otherwise you will distort the pan and it will leak.
I did not bother to remove the lines going to the cooler/radiator. I figured that pint or so of oil would not do too much harm. If I were dealing with a tranny that had shot [censored] and threw fileings into the oil, then flushing those lines and the cooler would be important too.
