Fluid change in trans

hotrodstew

Registered User
So last weekend i change the fluid and filter in my auto trans. I finished it up and drove it to find out that it now slips when you take off. It only does it if you slow down quick and do i cali stop. Fluid levels are good. Any idea on what this could be or if anyone else has had this happen to them.
 
Is your fluid level on the low side of normal? I think you might be sucking air. My car sometimes free-revs a little when I round a tight corner and try to accelerate at the same time. But the fluid level always checks out fine.

In the later 4R70W transmissions, Ford installed a pan with a central dimple to keep the pump from sucking air.
 
So last weekend i change the fluid and filter in my auto trans. I finished it up and drove it to find out that it now slips when you take off. It only does it if you slow down quick and do i cali stop. Fluid levels are good. Any idea on what this could be or if anyone else has had this happen to them.

Not sure what transmission you've got since you didn't mention what year the car is, but the filter on an AOD has a small square cork gasket to seal the top of filter to the valve body. If the gasket is missing or leaking it will cause some slipping and other issues. Easiest way to tell if that is the problem is to add another quart of fluid to raise the fluid level in the pan.

David
 
hmmmm

If the fluid has never been changed before it should have been left alone. The new fluid will make it slip and the only way to cure it is with a rebuild. Ask any transmission shop and they will tell you the same.
 
dont touch

i been afraid of that wives tale forever but went ahead and changed filter and fluid from pan ....no known history from previous owner... i just had to get some lucas in there.. other than one broken bolt every thing seems good
we will see if im back next week with issues???
 
I haven't had any problem with dropping the pan and doing a fluid change. But I have had a transmission die after flushing. So that's first-hand experience there.
 
i been afraid of that wives tale forever but went ahead and changed filter and fluid from pan ....no known history from previous owner... i just had to get some lucas in there.. other than one broken bolt every thing seems good we will see if im back next week with issues???
You'll be fine. I've had transmission shops tell me the opposite.. when asked, the attendant said with a chuckle. "well the truth is it was broken and changing the fluid did nothing to accelerate that."

Flushing on the other hand may involve the use of a solvent... on older transmissions with borderline rubber seals, it can cause the seal to dissolve. BTW, we're talking piston ring seals as the rest are case seals. There are no rubber seals in the valve body other than 1-2 end caps.
 
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