My friends truck (80K) automatic made a "bang" and then..nothing. It won't attempt to move. It made a noise similar to a chain-breaking in a transfer-case (which obviously isn't the problem). No symptoms leading up to the failure. Something broke. Quickly going from drive to park with the engine running, there's no noise from attempting to engage a moving park-sprag, suggesting it's not moving. Going from drive to reverse, you can detect the engine speeding up when going past neutral. The RPM slows in D or R just enough to tell.(similar to an AC compressor kicking in) He tried locking in the front hubs, nothing. It doesn't make any noise anywhere. Seems like a "clean break" somewhere. Any ideas would be greatly appreciated.

 

I think about the only thing you can inspect externally is the flex plate. Drop the inspection pan, 2 or 3 bolts, where the tranny bolts up to the bell housing.

 

I had something like that happen a couple years ago .In my case Iwas pulling away from a stop with a loaded trailer .Not sure now about the trannys action when moving the shifter then but the truck wouldn't move on It's own .I don't want to scare you but in my case the overdrive planetary gave out.Wasn't as expensive a repair as I had expected.Just my thoughts

 

you may have snapped the input shaft, mostly happens on trucks with higher horse power though during take off. LOL

 

Its possible but not likely, A518's aren't known for breaking their input shafts, but I'm not saying it can't happen.

That sounds like his transfer case is in gear and the coupler is intact. The slight RPM drop is consistent with the clutch and bands applying and putting a little load on the engine. Did you try putting it in 2 or 1 and seeing what happens?

 

Not sure what else he tried. But, he gave up and it's in a transmission shop and on the lift. We'll know something pretty soon. I'll let you know what they find. Thanks

 

I doubt that it's the flexplate - when mine ripped out there were all sorts of clanging and banging noises for some time until all the little pieces fell to the bottom. Then you could move the gear selector anywhere you wanted with no change in anything.

I'd guess some major blow-out in the valve body, leaving very low pressures.

Regards, DBF

 

hmmm, mine was broken in 1/2 when i bought the truck, so it does happen

 

He was told the output shaft snapped. (not input)

Has anyone ever heard of this happening?

If so...any idea where one can be purchased ? (prior to sucking it up and going to the dealer)




Right now, I love my old noisy getrag.

 

ouch the outputshaft he must of put it in park at about 20 miles an hour edit

 

Or, had his foot on the brake and built some boost????