Fluid/Filter change ruined everything??

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Nov 1, 2014
I've done the typical pan drop, new filter and fluid change at least a dozen times on Fords thru the years. This has never happened, and it's urgent.

Drove into the garage, dropped the pan, cleaned the magnet and put on a new filter, replaced the pan, and topped up with about 5q of fluid. (Used Castrol certified MercV)

Now it won't go into gear, any gear. Nada.

Any ideas? I've never seen anything like it, and am at a loss as to what could've gone wrong on a simple procedure.

I did idle it for a few minutes, check the fluid a few times to make sure it's the right level, and it is.

You can't really check the fluid level until it has cycled through the gears.fwd and reverse. Look at how much fluid came out. Are you sure you put enough in? Have you got anything to lose by adding more fluid?
Are you applying the brake when you shift into gear? If so....check to see if the brake light comes on when you do.
Go over everything you did . The only way to never mess up something is to never do anything. I know it din't help .
Vehicle would help
If its a 4F50N/AXxx/A4xx transmission, you did remember to pull the green o ring that always gets stuck up in the case housing, then you pushed it up with the new one.

You put enough fluid in? Didn't knock the vent or TRS while you were around the dipstick?
I've seen o-ring plugging as well as "almost right" filters that at first glance look correct but are not and prevent the fluid from being sucked up and pumped?

I would *think* that 5 QTS added, even if low would still have enough fluid to engage into gear. Please keep us updated.
What kind of filter was used? Are you 100% absolutely positive it is seated and sealed correctly? If it has o-rings, did the old ones come out, and are you sure the new ones were seated properly and lubed with ATF?

Personally, I'd probably add a quart of ATF as it won't hurt anything at this point. See if it will shift then. If not, it's time to drop the pan again and recheck everything.

Also, when you say it won't go into gear...will the shifter move, but the trans doesn't actually shift? Or is the shifter stuck in park?
he may have put the trans filter backwards. I'm not sure what his filter looks like. I know on my cars, the trans filter was bolted into the trans. so you could have bolted with the open filter side facing down instead of up. so the fluid isn't being sucked up through the filter first. does it matter? I always install the same so no confusion.
Thanks for great ideas. I'll clarify the shifter works, it's that they won't engage, which of course makes me suspect things like are mentioned here.

Yes I dug out the old green seal. Yes I made sure the new filter was seated well, and it's quite tight.

Grr, guess I'm getting dirty again today and taking it all apart. Will keep you posted.
Originally Posted By: 901Memphis
Gotta be the filter not seating right so it's not drawing fluid.


....and also double check the o-ring seal.

Dropped the pan again, everything looks fine. One thing is odd. Sucked on the filter, and there's of course a little resistance. However, sucked on the old filter and there's almost no resistance.

Should there be any resistance in the filter? I know this is really a redneck troubleshooting technique, but I'm grasping at straws.

The fluid I took out was dark, but not stanky. I refuse to believe that new fluid could "break" the pump or anything else, no matter how much "crud was holding it together", especially since there was no crud. Magnet had a small bump of smooth graphite like residue, no metal or anything even gritty feeling.
I haven't been a Ford guy for many years, so no specific knowledge to help-but I generally just change out the filter earlier in the vehicles life and then only drain/refill. If mine, I probably would have just put the 'old' filter back on and refilled-maybe you do have a 'funky' replacement? Get another filter of a different brand?-good luck
That is strange. I really sounds like an issue with the shift linkage/mechanism, though it's hard to rule anything out. It's possilbe a peice of the old filter neck gasket/o-ring was stuck in the orifice, and got sucked into the tranny. When you shift into gear, does the RPM of the engine drop slightly?
Was the new filter saturated with fluid? If it wasn't then the level wasn't high enough.

You possibly got a bad filter if it was below the fluid level.
Did you use a Motorcraft filter? Similar thing happened to the wife's Explorer after a tranny service. It shifted poorly, then would not shift at all. My mechanic would did the job towed it back to his shop and opened it up and replaced the aftermarket filter with a Motorcraft and all was well after that.

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