trannny won't shift
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trannny won't shift
I just had my engine and tranny redone in my 79 F150 automatic. It ran fine for about 50 miles. Now the tranny won't shift and I don't have 3rd gear of my 3 speed transmission. I checked the fluid and it is full. I have vacuum to the modulator valve. I am wondering if the valve could be bad even though it is new or something more serious is going on?? Help !!
Thanks
MTrumpy
Thanks
MTrumpy
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Joined: Feb 2003
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From: Oak Harbor, OH
Yeah, get on the freeway and run it up to around 80 see if it shifts. If it does then you're kick down is stuck. I'd get under the truck and make sure it all moves freely. Usually a faulty or bad modulator results in early shifts and bucking between second and third.
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Kickdown is free and easy. It is an automatic C4.
And it works just as the one reply stated. It pops in first when in D. It goes to 2nd if you shift to second and will never hit 3rd.
And it works just as the one reply stated. It pops in first when in D. It goes to 2nd if you shift to second and will never hit 3rd.
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Joined: Feb 2003
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From: Oak Harbor, OH
My question is how high are you letting the engine rev before you back out of it? I had a C6 behind a 351w in a van that I slid off the road in the snow and ice, the trans had a huge chunk of ice on the side of the trans holding the kickdown in the WOT position. It wouldn't shift into third gear until around 70mph. With the 4:10 gear in the rear end it sounded like the motor was gonna come apart, but it DID shift. I'd pull the line off the modulator and see if it leaks fluid out. Also if the line feels spongy that's a good indication that the modulator has failed and is letting fluid get sucked into the motor.
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I am letting the engine rev to 4000. The engine is freshly rebuilt as is the tranny, vacuum lines are new, modulator valve is new. I know new, don't always mean it is working properly. I thought maybe someone might know of a similar experience. I am trying everything that has been mentioned here and I do appreciate your help. So far I haven't solved the problem. Thanks
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Joined: Oct 2005
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From: Oregon
I ended up needing a rebuild AFTER my tranny started acting life this, turned out the rebuilt motor had beat up the old tranny, and it was getting clogged up with metal bits.
If nothing else works, drop the tranny pan and check for metal shavings, I'm hoping this isn't your problem, but this is what happened to me, so I'm just throwing it out there.
Was it a home rebuild or a shop rebuild?
If nothing else works, drop the tranny pan and check for metal shavings, I'm hoping this isn't your problem, but this is what happened to me, so I'm just throwing it out there.
Was it a home rebuild or a shop rebuild?