I've owned this truck since new and I just turned 100K miles. Here lately when I accelerate slowly, my transmission shifts and I hear a chatter, usually from 2nd to 3rd gear, or from 3rd to 4th. When I shift under normal acceleration it shifts fine.

While checking my service records I found that I had the transmission first service at 32K mile, but it didn't indicate whether I changed the filter. With that low of mile I probably didn't, just the fluid change.

Next I had the transmission flushed at 68K miles.

Now I think I am due for another service and I am really confused as to what the proper service to be done. Some say all I need to do is drop the pan and change the filter, then refill with 8 quarts. Others are saying that is not correct and I need to flush the system.

Also, do I have an external filter? Some shops are not aware of an external filter, and neither am I.....but that doesn't mean much either.

Regarding my chatter when shifting, do I need to just add an additive for this issue?

 

I should have posted this in another section....sorry.

 

You should change the fluid. Not just what's in the pan, but all the fluid. Here's how. Changing ATF Fluid in a E4OD and 4R100 transmission .: Articles
The internal filter is the only filter the transmission has. It is not a very fine filter and it is good for the life of the transmission. You don't need to change it until the trans is rebuilt.

 

So if I take it to a shop, a flush would be all that is needed, correct?

 

I also has a shudder when shifting at slow speeds. I was due for service so I took it to my local Ford dealer and they flushed and refilled with new fluid. The trans shifts great now.

 

Yes it is. No chemical flush, just new fluid.