4R70W problem
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4R70W problem
Have a '99 Expedition, 2WD w/ 4.6L and a 4R70W transmission. All of a sudden, w/ no prior drive-ability problems, it began missing 2nd gear. 2nd is still there (from a manual standpoint) and does not seem to be slipping.
When cold, for a couple of shifts, it acts as if there is no problem and shifts normally right from 1st to 2nd with no throttle 'manipulation'. After it warms up, it will hold 1st up to about 3000 RPM before shifting into second; occasionally it will require a gradual reduction in throttle pressure to make the shift to second.
When slowing and downshifting, it drops straight form 3rd to 1st, or at least appears to.
Under heavy acceleration, from 3rd to what should be 2nd, it acts as if it's thrown into neutral until you release some throttle pressure; but again a manual shift engages 2nd w/ no apparent slippage.
I know this thing has multiple solenoids, but was just wondering if these symptoms are indicative of problem w/ a particular solenoid. Help!!!!
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When cold, for a couple of shifts, it acts as if there is no problem and shifts normally right from 1st to 2nd with no throttle 'manipulation'. After it warms up, it will hold 1st up to about 3000 RPM before shifting into second; occasionally it will require a gradual reduction in throttle pressure to make the shift to second.
When slowing and downshifting, it drops straight form 3rd to 1st, or at least appears to.
Under heavy acceleration, from 3rd to what should be 2nd, it acts as if it's thrown into neutral until you release some throttle pressure; but again a manual shift engages 2nd w/ no apparent slippage.
I know this thing has multiple solenoids, but was just wondering if these symptoms are indicative of problem w/ a particular solenoid. Help!!!!
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Joined: Apr 2005
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From: duncan oklahoma
drop the pan and replace the 1-2 accumulator piston,springs and cover.you might have to do a light cleaning of the bore.the accumulator id the silver dollar sized hole at the front driver side of the trans,after you drop the pan you will see what i am talking about.the seal is probably starting to bypass fluid which keeps the pluid from getting to the intermediate clutch(second gear).when you put it into man second a diff. set of clutches are used. good luck.
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I-m tech is DA MAN!!!
I-m tech... YOU DA MAN!!!
The bottom spring between the piston & retainer was broken in (3) pieces and had lightly scarred the bore. I polished the bore and replaced the parts and it shifts like $ new money $.
A BIG THANKS!!! Everyone elese that had looked at it said 2nd was gone and it needed to be overhauled. You saved me about $1650...
Thanks Again,
Matt
The bottom spring between the piston & retainer was broken in (3) pieces and had lightly scarred the bore. I polished the bore and replaced the parts and it shifts like $ new money $.
A BIG THANKS!!! Everyone elese that had looked at it said 2nd was gone and it needed to be overhauled. You saved me about $1650...
Thanks Again,
Matt
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More 4R70W problems...
Same '99 4R70W in Expedition w/ 200K miles started w/ slight 'scraping' noise (similar to worn brake pad hiss, but not grind) and then within an hour got to a point it would not pull. Can shut engine off and restart and drop into gear and will pull for approx. 30 seconds and then it 'neutrals'; will always do this in approx. the same timeframe. When it starts off you have to 'feather' throttle to make shift. Haven't dropped the pan yet, but the fluid on the stick still looks clean and doesn't have a burnt smell. Could it be pump going bad? Or other ideas before I go buy a rebuilt?
Thanks!
Matt
Thanks!
Matt
