4R70W slipping in 3rd

[Trucken]

I just discovered this forum, and I'm amazed at the wealth of information. Thanks for all your posts! I just read through the current threads and didn't see the scenario I'm experiencing with my truck, which has the following specs: 2000 F150 4.6L 4WD 4R70W ~180K miles What happens is that I get to a certain point on the freeway where there's a hill, and the tranny shifts down to 3rd as I would normally expect it to. The RPMs go up as usual, but instead of my speeding up or at least maintaining speed, the truck slows and doesn't seem to be getting full torque. I'll gradually slow down as I get to the top of the hill then the tranny shifts into OD when I start down the other side, and all works normally. I've also noticed this going up a steep freeway onramp from a lower gear, so it's not always after shifting down, but it is always in 3rd that it seems to slip. The problem has come on gradually and is getting worse. At first I didn't notice a problem every time, and the slippage seemed to be minor. Now it's every time and slips a lot. I checked the fluid level and it is full. I replaced the torque converter about 4 years ago, and I'm ashamed to say that was the last time I changed the fluid and filter. I also did a lot of towing a couple of months ago, including towing up hills, and I'm worried that I've ruined the transmission. Is there a reasonable likelihood that the problem could be something simple like bad fluid and/or filter, bad torque converter, valve body blockage or other problem that could cause this slipping in 3rd gear? I'd like to try the simple solutions before having the tranny rebuilt/replaced, but I don't want to sink any more money and time into this one if it's clearly a rebuild/replace situation. Any ideas on what's going on with my tranny?

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[scruffy]

Sounds like your direct clutch is slipping. You should probably drop the pan, change the filter and refill, and if your lucky that will help the slippage. If not then you might need a rebuild.

- Erik