munro_98

I drive a 04 F-150 Lariat 4x4 with 203,000 miles, with a 4R75E transmission.

The transmission recently starting slipping when climbing hills or increasing speed.

There is not check engine light and doesn't make a difference if O/D is on or off, also doesn't make a difference if its in 4x4 or 4x2.

I changed the fluid about 30,000 miles ago and have never had an issue with the trans.

What do y'all recommend doing? I haven't been able to fine a used trans for less than $1,000 and don't want to spend that much on an older truck!

Thank you, Will

Martian

Any codes?

munro_98

Unfortunately haven't been able to check yet

mitymerc

what filter did you use when servicing? if you used an aftermarket filter, pull the pan and make sure the filter is still seated in the valve body. it is very common for the aftermarket filters to separate from the rubber grommet and fall into the pan.

650NutKase

check the fluid again. Maybe it just needs another servicing.

munro_98

Thank you, I will definitely pull the pan and check/change the filter. What fluid, and filter/gasket kit do y'all recommend?

650NutKase

Any Mercon V should be fine. I'm running Walmart's Super Tech semi syn and it's doing very well. As far as filter, MC is the only one I recommend. Rockauto.com has them dirt cheap.

munro_98

I pulled the pan and replaced the filter. Didn't see any issues with the filter and it fit tightly. I'd say the magnet in the pan had a normal amount of debris. Trans still slips the same amount.

Where should I go from here?

650NutKase

Did you go with a Motorcraft?

If the trans slip is the same, you're down to worn clutches or solenoid issues. I'd try a bottle of "stop slip" to see if it helps. If it does, the issue is burnt clutch packs.

munro_98

Yes I used Motocraft and drove it for a few days. The conditions were the same.

I then put a bottle of Lucas "stop slip" in and it almost made conditions worse. Either my clutches are totally gone or there is another issue.