Trubo 350 auto will not hold vehicle from rolling back in park
11-22-2004, 09:34 AM
#1
Pro
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Turbo 350 auto will not hold vehicle from rolling back in park
Hi, guys I have a problem related to my transmission for my 1976 GMC half ton. It’s a turbo auto 350. I checked my shop manual for my 1980 corvette for a bit of guidance with the problem I have. I came home the other day with the truck, threw it into park and the truck started to roll back on the drive way! I rechecked the column shift and I was in park, but it was not holding. I shifted done to first and then back into park and the same problem, the vehicle is not staying in park as it should. I checked the linkage, shift column and this was fine. I was able to get into all 3 gears, neutral and reverse with out any problems, but in park it is not holding. The craziest thing is if I shut the truck off in drive and then shift the into park, it engages and is fine? I was on some bumpy gravel roads when I came home prior to this problem, any relation? When I shift into park when the engine is running is not holding, but if I turn the truck off in drive and then shift into park it is fine?
I checked my shop manual for guidance and there is a shift linkage rod, spring and Parking pawl that enables you to shift into park and have the vehicle hold. To access it I would have to remove the tranny pan which is not a problem, but what am I looking to repair here. Can’t under stand why it does not work going from drive to park when the motor is running. Any help from the tranny experts would be greatly appreciated. :o
Thanks
I checked my shop manual for guidance and there is a shift linkage rod, spring and Parking pawl that enables you to shift into park and have the vehicle hold. To access it I would have to remove the tranny pan which is not a problem, but what am I looking to repair here. Can’t under stand why it does not work going from drive to park when the motor is running. Any help from the tranny experts would be greatly appreciated. :o
Thanks
Last edited by RATT7; 11-22-2004 at 10:31 AM.
11-22-2004, 10:35 AM
#3
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Thread Starter
If the parking pawl is sheared, would that not effect the park function when I turn the motor off in drive and then shift in park ? I not sure why this happens, but when I shut the truck down in drive and then shift into park the truck will not roll back ?
11-22-2004, 10:43 AM
#4
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I dunno. What I do know (I only work on Fords at work, so I don't know much about GM trannys inside) is the the pawl is what keeps it from spinning inside and therefore your truck from moving.
11-22-2004, 05:11 PM
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Yup, it might not be going all the way into park, I assumed that you checked that. Take the cable off the trans, put the input arm all the way into park and see what happens. (PLEASE chock the tires and jack the rear end with the engine off, at the least) If it locks, your linkage is mal-adjusted. If not, you'll just have to pull the pan and take a look. No way around it. One more thing, if you linkage is adjusted wrong, has slop in it or whatever, you can burn the trans up if it is going only partially into gear while you are driving it, forward or reverse.
11-23-2004, 10:48 AM
#9
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The linkage is a little loose but it is no different then prior to the problem - I will check the linkage again. I noticed that all the gears works, including Neutral. But if I shut the motor down in drive and then shift into park, then park holds. It sounds like the linkage. Thanks - I will let you guys know of the outcome 
