Transmission flush

If you change the fluid it might just wash down the clutches and put sludge in the pan. And clog up the filter then you have real problems.
Is what I was told by been there done that.
 
Do PM when it is due. Fewer problems that way.
 
If you change the fluid it might just wash down the clutches and put sludge in the pan. And clog up the filter then you have real problems.
Is what I was told by been there done that.
The ones to really be concerned about when doing a fluid change/flush, are those transmissions where the filter is internal and cannot be changed without disassembling the transmission, Hondas, Acuras, some of the later GM and Ford front wheel drive units, if the fluid has gotten to the varnish stage, then I would be very cautious about trying to change it with new fluid, transmission fluid is high detergent, and can start to clean the inside of a varnished unit, if you can't change the filter, then what gets cleaned ends up in the filter, sometimes clogging it up.
 
The ones to really be concerned about when doing a fluid change/flush, are those transmissions where the filter is internal and cannot be changed without disassembling the transmission, Hondas, Acuras, some of the later GM and Ford front wheel drive units, if the fluid has gotten to the varnish stage, then I would be very cautious about trying to change it with new fluid, transmission fluid is high detergent, and can start to clean the inside of a varnished unit, if you can't change the filter, then what gets cleaned ends up in the filter, sometimes clogging it up.
Is what I was told.
 
In the 14 years I was in auto service, I probably flushed over 1200 transmissions. The only failure I ever knew of was a Ford Taurus. Customer came in requesting service....which was always a red flag. I tried to talk him out of it due to the make/model/mileage plus the symptoms he described. He insisted the service anyway.

I made him sign a waiver that released me from any liability. We flushed it...he left and made it about 2 miles. I've used Wynn's, Symtech and T-Tech fluid exchangers. I can honestly say that the T-Tech is the ONLY one I'd ever consider using on my own vehicle.

In my shop, any vehicle over 100K miles without a verifiable service history, I'd decline the request for a trans flush...or you signed a release waiver. Certain makes and models, I wouldn't touch regardless. I've been out of the game since 2007 and I know a lot has changed with fluid technology, etc.
 
I know a lot has changed with fluid technology, etc.
Definitely, CVT units take a special fluid, Nissan rear wheel drive units since 2005 take their own special fluid, as do Toyota units since about that same time, using a fluid other than factory on Toyotas and Nissans can result in a shudder on shifts and on lockup, manufacturers are designing the programming for the transmissions around a specific fluid, with specific friction modifying characteristics, as well as the type of clutch frictions the unit is built with, a different fluid can cause all sorts of shifting issues.

Even Ford has gotten into that arena with the 6spd rear wheel drive units they have had out since about 2007, a unit designed in Germany by ZF industries, taking its own special fluid as well.
 
If it's done correctly it WILL not cause any new issues. Does changing the oil on your truck cause it to Blow up?

Transfixer, I used a none pressurized system. The vehicle had to be running and at operating temps. I never had any issues. I loved the 4r70w's as you stated they are a great transmission and are easy to build. If memory serves me correctly the year model of the OP's truck is along the years Ford removed the drain plug for the converter. which to me always meant half a service unless you flushed it. Because 6 quarts of the 12 required in the 4r70w are in the converter.

To the OP, It's highly unlikely changing fluid either method will cause you a problem. Good luck.
If it's done correctly it WILL not cause any new issues. Does changing the oil on your truck cause it to Blow up?

Transfixer, I used a none pressurized system. The vehicle had to be running and at operating temps. I never had any issues. I loved the 4r70w's as you stated they are a great transmission and are easy to build. If memory serves me correctly the year model of the OP's truck is along the years Ford removed the drain plug for the converter. which to me always meant half a service unless you flushed it. Because 6 quarts of the 12 required in the 4r70w are in the converter.

To the OP, It's highly unlikely changing fluid either method will cause you a problem. Good luck.
Not a valid comparison ... Transmission fluid has a detergent in it to clean the bands inside the transmission. If the transmission has not been serviced on a regular basis and there are high miles on it you stand a chance at causing the transmission to slip by replacing the fluids. Completely different story if you don't service the engine in your vehicle.
 
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