4R70W transmission loss of overdrive
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4R70W transmission loss of overdrive
Just thought I would post, in case this scenario ever happens to anyone else: Two days ago, I pulled out in traffic and had to accelerate rather harshly (overdrive on and working fine), as I pulled up to the red light and stopped everything was working fine; however, as I accelerated at the green light, I ran thru 1st, 2nd, and 3rd gear, but lost 4th gear (i.e. overdrive) the engine just revved to 3000 rpm with no engagement.
A Looong story short, I troubleshooted from the start: checking electrical connections and fluids, dropping the tranny pan and checking the filter (and the bottom of the pan of course heh), and even running an ohm meter across the shift solenoid. Well I finally did what I didn't want to do today, which was drop the valve body, it seems that the 'servo' is held in place with a rather large snap ring, the snap ring over a period of time (103,250 miles...)had rubbed the metal surface of the servo and caused metal fragments to fall into the valve body. I opened the valve body up and found that a large piece of metal had pinned the 'overdrive regulating valve' in the open position. I removed the metal, cleaned the valve body, reinstalled the servo, valve body, filter, and pan, and whammo!...runs like a charm again.
Saying all of this, I had first taken it to a repair shop and they told me that it was toast and I would need a new transmission. Admittedly I am sure I did some damage to the band around the shaft, but I figure that repair will come in time; however, for right now, I just saved a $1400 repair bill. I did find a good tranny mechanic that told me that it is pretty typical after 80-100,000 miles to start having problems with the servo unit (rubber coming apart, or metal fragmentation dropping into the valve body).
So far other than a (egads) #4 ignition coil, and a speed sensor going bad, that is the only problems I have had, and for 103,000+ miles that's not anything to complain about.
Go figure I own a 5.4L 4X4 with over 100,000 miles and I can't complain
sorry if I confused anyone, but thought as much info as I learn from this board, maybe I could help someone else out in the long run.
A Looong story short, I troubleshooted from the start: checking electrical connections and fluids, dropping the tranny pan and checking the filter (and the bottom of the pan of course heh), and even running an ohm meter across the shift solenoid. Well I finally did what I didn't want to do today, which was drop the valve body, it seems that the 'servo' is held in place with a rather large snap ring, the snap ring over a period of time (103,250 miles...)had rubbed the metal surface of the servo and caused metal fragments to fall into the valve body. I opened the valve body up and found that a large piece of metal had pinned the 'overdrive regulating valve' in the open position. I removed the metal, cleaned the valve body, reinstalled the servo, valve body, filter, and pan, and whammo!...runs like a charm again.
Saying all of this, I had first taken it to a repair shop and they told me that it was toast and I would need a new transmission. Admittedly I am sure I did some damage to the band around the shaft, but I figure that repair will come in time; however, for right now, I just saved a $1400 repair bill. I did find a good tranny mechanic that told me that it is pretty typical after 80-100,000 miles to start having problems with the servo unit (rubber coming apart, or metal fragmentation dropping into the valve body).
So far other than a (egads) #4 ignition coil, and a speed sensor going bad, that is the only problems I have had, and for 103,000+ miles that's not anything to complain about.
Go figure I own a 5.4L 4X4 with over 100,000 miles and I can't complain
sorry if I confused anyone, but thought as much info as I learn from this board, maybe I could help someone else out in the long run.
