When the thermostat is below 170°F the flow to the coolers is 10% of normal. The other 90% is recirculated inside the trans. So if you're doing a flush and the trans isn't hot enough instead of flushing out the old you are just mixing the old and new.

 

With the thermostat inside trans is it even possible for me do service my trans properly with out the dealer? Does the trans flush replace the fluid inside the torque converter? I have 34k miles & last year dealer "did the fluids". I'm guessing they may have just drained pan & refilled. I want to do what is absolutely best for the truck. Thank you much.

 

If you maintain the trans above 170°F the whole time you're doing the flush it will change the fluid in the torque converter and the transmission. That's why you need a heated flush machine.

 

I'm towing now 63 outside air tranny temp @ 157 6 by 10 enclosed 4k maybe. So only 10% is going through cooler now?

 

Mark is right. At 165 to 170 degrees, an internal valve will open n allow the tranny fluid to flow around freely. Ain't no way we can maintain tat temp without scalding ourselves. Hence the heated flush machine. Those things flush everything n put back as well. However, I'm fine where I am. I'm gonna change out my tranny fluid again at 10000 miles cos the one I changed was burnt. I'll be OK. Even changing the internal filter was a little much but I'm glad I did cos the previous owner did nothing on maintenance. Lol.

 

I Flushed my 05 @ about 140,000 miles, drained the fluid, put the plug back in added 2 gallons and drove about 15 minutes. I did this 4 times then on the fifth time I replaced both Filters and topped it off. I did my 06 the same way @ about 130,000 miles.

 

Yes, that's right.

 

serviced my trans last weekend, drained the fluid out the pan (did not drop pan or replace screen) and replaced the external filter. External filter was pretty nasty. 8 qts of mercon SP and its shifting like new again.

 

Good to hear. Being paranoid me, I'd change the internal filter every other time u drain the fluid.

 

Did both filters on a buddy's F350 and the truck drives and shifts much better. We still need to do a complete flush on his, but it was obvious that it needed to be done.

 

The tranny doesn't hit 170 driving empty in 30 minutes let alone 15.

 

Unless you are towing my 30' fifth wheel........ up a mountain. LOL

 

Since i plan to change the internal filter i figure it would be simple to drain the torque converter and dump all or most of the fluid. Is there something I'm missing here? My handy dandy Chilton manual states that to drain the torque converter and replace the plug with new one. Any thoughts why to replace the plug?
When adding the new oil, approx. 17 quarts, do I pour all 17 down the dipstick port? The manual said initial add is 6 1/2 quarts and check from there. Seems like a slow process.
I plan to at least measure quanity that comes out to have an idea of what goes back in. Also, said after a favorable stick reading to run through the gears with foot on break.
Is that it?

 

There is no drain plug on the torque converter. If you find one please let me and Ford know.

 

Will do
Thanks