chevy trans. problems

[dairyman]

My dad just told me tonight that his truck has developed a problem of rolling away when the truck is in park. I'm thinking something went bad in the transmission with the parking mechanism. the truck is a 1994 chevy silverado 2500 2wd. with a 454 engine. I would appreciate any help or thoughts on what is wrong with it and if i would be better off having someone fix it because im not all that familar with automatic transmissions but can do some simple repairs to them. thanks for any help.

Dave

 

[Bob]

"I'm thinking something went bad in the transmission with the parking mechanism."

Yep. You nailed it. It's POSSIBLE there could be a problem with the INTERNAL park apply mechanism that can be repaired without dropping the tranny, but don't "hold your breath".

 

[Anonymous-0]

It's caused by throwing the truck in park while the truck is even slightly still rolling to a stop. Over time, you're gonna lose that dog. This is found with impatient and hurried people, but in no regards to you, just stating a fact by a tranny guy.

 

[Anonymous-0]

The end of the parking pawl is probably broken off. A spring loaded cone is used to push the pawl into the park gear on the output shaft and lock it into park. The spring is used to push on the cone until the parking pawl tooth finds a blank tooth on the parking gear as it is rotating and then the pawl tooth drops in and the cone locks it there. Hopefully the case isn't cracked also from the pawl pushing against the cone.

 

[Brokenwrench]

Alot of the park mechanism in a 4L80E can be serviced by dropping the pan. What Vern is talking about with the apply rod, spring and bullet is what I`d go after first. I`ve seen more than once where the rod has become bent alittle and now the spring can`t force the bullet quite to the end of the rod, so you will get a partial engagement, or park will hold on the level.
Most of the park problems I`ve seen are either adjustment issues, or issues with the apply rod. The park gear is part of the rear planetary assembly and all but impossible to break. Breaking the pawl is pretty tough as well. There is a hold down that holds the bullet against the pawl, that could be worn but doubtful.
Drop the pan and check er out, or if you have a good mechanic have them do it. Post back whatever you find. Hope this helps BW

 

[dairyman]

Thanks for the ideas everyone it looks like i have some checking to do. I'll let you know what happens with it.
Dave

 

[Frankie]

My grandfathers 01' Dodge Dakota has similar automatic transmission problems just with every gear. If the shifter isnt in a gear completely the trans will knock when its moving but not when fully engaged. No problems with it, yet.

 

[dave guest]

Check your linkage and see if it is really going into park. Adjust the rod a little longer if I remember correctly or pull rod out of hole in linkage, push firmly into park, adjust rod a skosh longer and insert together and pin. Done this lots of times in 70's. People astonished at how easy it could be. Don't use park to stop vehicle as previously suggested.