98 4R70W problem
#1
02-21-2009, 06:43 PM
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98 4R70W problem
98 F150 Offroad 4.6 w/4R70W and approx 124K miles,
Today while driving down a nice flat country road at approx 35 mpg w/the OD off I noticed the tranny "slip" on a couple of occasions and return back to normal.
What I mean by slip is that it seemed to disengage (like when one pushed in a clutch). The rpm raised but the event was so fast I almost didn't notice it.
Other than the tranny developing a sloppy 1st to 2nd shift immediately after the last tranny flush & fill @ 55k miles, the truck/tranny has been trouble free.
It's got approx 124K miles now and I haven't noticed any problems when running w/the OD on.
The truck became a weekend use only about 5 yrs ago and avgs only about 50 - 100 miles per week.
Is this a symptom of contaminated fluid?
Today while driving down a nice flat country road at approx 35 mpg w/the OD off I noticed the tranny "slip" on a couple of occasions and return back to normal.
What I mean by slip is that it seemed to disengage (like when one pushed in a clutch). The rpm raised but the event was so fast I almost didn't notice it.
Other than the tranny developing a sloppy 1st to 2nd shift immediately after the last tranny flush & fill @ 55k miles, the truck/tranny has been trouble free.
It's got approx 124K miles now and I haven't noticed any problems when running w/the OD on.
The truck became a weekend use only about 5 yrs ago and avgs only about 50 - 100 miles per week.
Is this a symptom of contaminated fluid?
#2
02-21-2009, 07:02 PM
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I would go ahead and change the fluid and filter and go from there. I highly doubt its the tranny. You are probably right in geussing that the fluid is old.
I own a 1993 Crown Vic with 30,000 miles on it. Everything is original including the brakes. my tranny starting making a humming noise, like when you go over a rumble strip on the highway. I changed the fluid in the tranny and that fixed it. Time will also deteriate fluids as well as mileage. Good luck
bowdog
I own a 1993 Crown Vic with 30,000 miles on it. Everything is original including the brakes. my tranny starting making a humming noise, like when you go over a rumble strip on the highway. I changed the fluid in the tranny and that fixed it. Time will also deteriate fluids as well as mileage. Good luck
bowdog
#3
02-22-2009, 12:04 PM
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install a new 1-2 accumulator piston.sounds like the seal is weak.the piston is designed to take up some of the shock when the vehicle makes the 1-2 shift.if the seal is weak it cant apply fluid pressure to the intermediate clutch to get second gear.drop[ the pan its the dollar sized hole at the drivers front of the trans.would also be a good idea to replace the springs with the piston because they normally fatiuge and break and cause a harsh shift.
#4
02-22-2009, 04:28 PM
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Thanks for the replys,
bowdog, looks like we have similar trucks. Mine has been a great truck. Been thinking about a fluid & filter change for quite awhile, guess the time has come.
l-m tech, I'm pretty capable of most mechanical repairs except auto tranny's. For some odd reason I've always left getting into them to others. But that was then and this is now, I'm willing to tackle this, especially since it can be down for awhile
I'm assuming the 1-2 servo piston (& springs) are accessed by dropping the pan. Are their any "got-ya's" involved? Is there any picture references for the 4R70W on the Net?
Thanks
bowdog, looks like we have similar trucks. Mine has been a great truck. Been thinking about a fluid & filter change for quite awhile, guess the time has come.
l-m tech, I'm pretty capable of most mechanical repairs except auto tranny's. For some odd reason I've always left getting into them to others. But that was then and this is now, I'm willing to tackle this, especially since it can be down for awhile
I'm assuming the 1-2 servo piston (& springs) are accessed by dropping the pan. Are their any "got-ya's" involved? Is there any picture references for the 4R70W on the Net?
Thanks
