automatic transmission flush

Is it really some kind of power flush or is it just a full fluid exchange?

I would tend to drain and fill the pan and then do the exchange to get new fluid in the torque converter. Replacing the filter is over rated. More of a strainer. The media just does not get dirty like an engine oil filter.

So glad I have a torque converter with a drain plug.

Depends...

I used to say flush all the time, but that is based on my personal
routine of flushing all my automatics on a regular schedule of 20K or
two years, whichever came frist

Well, bought a used 2000 Honda Odyssey. IIRC, around 130K miles when it
started to shift 'funny'. Previous were Christian Missionaries who
moved to China. Found pet hair, candy, spilled soda, etc where they
missed with the steam cleaner...it must have been the 'bus' for church
trips...

Flushed it and the tranny shifted better for a few hundred miles...then
it barfed and wouldn't shift right at all.

Had it rebuilt and is good for a long time, or hope it will be...

IF the OP's automatic hasn't been flushed before. It has been used
HARD towing heavy...then just a pan drop and no complete flush.

What happens is that the ATF in doing it's job, burns at the tips
of the TC vanes. That is the 'slip' of any automatic and why all
now have a lock up to prevent that 'slip'

That 'slip' is where the AFT shears and that is also where the torque
multiplication comes from

IN shearing, it can get hot enough to burn the ATF and cause it to
oxide and form varnishes that will then coat various surfaces

As the valve body parts wear...that varnish coats to mask that wear
and tear

Flushing the whole charge will introduce new ATF with all of the solvents
built in. A pan drop and change will only change a percentage (small)
of the whole charge. So the solvents are diluted

Solvents will remove some/most of the varnish to then have the moving
parts either loosey-goosey or clog a moving part

The OP's at 90K miles. So up there and if towing hard/heavy, then
there is a danger that the OP's tranny is varnished enough to cause
a problem if a whole flush is done

Most of the ATF is in the TC. A small portion is in the tranny pan
of 'most' automatics.

Oops

I don't know about 2011 but ford used to say do not flush.

gkainz wrote:
transmission experts I know say "DO NOT FLUSH!" ... drain the pan, change the filter. If you want the TC fluid changed, remove the output line to the trans cooler and idle the engine. As the old fluid pumps out, add the same amount into the fill port. Once you have clean fluid pumping out, stop, shut down, reconnect, restart, check and set proper fluid levels.

Just had our Toad done that way.

Money generator, nothing wrong with old way. No reason to flush all the wear debris around in the spool valves, and pray in shifts correctly after.

That is the mileage for a transmission fluid recommended by the Ford manual for normal maintenance.

I have previous trucks and Expy done at recommended mileage with no subsequent problems.

Edit: Oops! 90 k was the previous truck. 2012 says 150,000 miles for transmission fluid change.

Boat payment IMO. Ford recommends a drain and fill with external filter change, not flushing. Dropping the pan may be good but again, not recommended. And since there is a thermostat inside that controls flow to the cooler, the oil in any flush machine must be heated to open the thermostat so ask if that is done if you decide to go with their flush. And if they use chemicals to flush-run away! They cause more harm then good.

transmission experts I know say "DO NOT FLUSH!" ... drain the pan, change the filter. If you want the TC fluid changed, remove the output line to the trans cooler and idle the engine. As the old fluid pumps out, add the same amount into the fill port. Once you have clean fluid pumping out, stop, shut down, reconnect, restart, check and set proper fluid levels.

I prefer to have the pan removed and checked for debris. My transmission place also blows old fluid out of cooler so as to remove old fluid.
Only bad thing is the converter doesn't always drain leaving some old fluid there.
Transmission flushes do not replace the filter if equipped.