automatic transmission flush
I'm due the 90,000 service on my 2011 F350 diesel. The dealer is recommending a transmission flush. Is this worth it, or are they just trying to make a boat payment?
Forum Discussion
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.
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.
