I have a '96 Dakota 3.9 automatic that makes a growling or groaning noise (lower-pitched than a whine) that occurs on deceleration when the overdrive is on. The noise will continue on acceleration but is initiated on deceleration and only stops when I am almost to a complete stop and the trans drops into first gear. If I accelerate from a complete stop through all four gears (without decelerating) there is no noise. Any time the noise occurs it can be eliminated by turning the OD off. If I accelerate with the OD off then turn it on at about 50-55 mph it works normally. By the way, the truck always drives and shifts normally even with the noise, it just sounds bad like something is about to go seriously wrong. Does anyone have any suggestions about what might be wrong or what I can do to prevent a major failure?

 

Before you go into possible tranny problems, have you inspected all the engine supports and made sure the exhaust system is not having metel to metal contact somewhere?...There may indeed be damage in the OD section of trans, but all you can do at this point is make sure you have plenty of oil going through your cooling lines....the return line provides lube to the rear section of trans and the OD section...

 

think i would go to a tranny shop and let them test drive it. what you describe sounds like the planetary gear but just in OD, maybe not ????????????

 

That would be highly advisable.......even though the OD planet is suspect, it does not have to be......

 

Thanks for all the replies, I could not find anything externally wrong. I am reluctant to take it to a tranny shop because I can't imagine a shop saying anything other than "you need a new trans" which would cost about twice what I paid for the truck. Maybe I should though since it is otherwise a very nice truck that I am growing fond of. Does anyone think I am doing any harm but driving with the OD off until its needed at 50-55mph at which point it makes no noise? Is it going to get worse no matter what I do?

 

get worse, probably........would try independant tranny shop, maybe two, yes your right when you say"you need a new trans" but nothing to lose but a little of your time. don't know what other options you have, if they say need a new tranny then you could go junkyard shopping and do it yourself if you are so inclined to do that.
keep us advised....

 

I have same noise when OD is on only. tried Lucas tranny lube, which helped for a while. rebuilt tranny at ~85k miles. now have 161k miles. Gonna have to fix it or replace... not sure of cost. any idea?

Tnx for any feedback!!

Pete