Transmission Issue?

[aaronbtb]

I'll start this by explaining the issue. I was driving home from work, I was turning left at a light and halfway thru the intersection, i felt a hard jolt, (could of bin a shift) and I lost power, the engine bogged down. I tried to give it more gas to get off the road so I can pull over and it wasn't responding, it was just slowing down. Once I pulled over I put it in park, then D and drove off, everything was fine. I stopped again to check my transmission fluid, as soon as I pulled the transmission dipstick white smoke came out, it smelt like trans fluid. Fluid level was on the cold because the truck had only idling for 10 minutes, then driven for 5mins. Drive it home just fine, 0 issues. After about 30 mins I decided to pickup a buddy and drive it around to see if it'll do it again. Halfway to his place it did it again, I was going maybe 50km/h and it just felt like it randomly down shifted, I let off the gas and I can hear the engine roaring like its in second gear, I let it coast to a stop and put it back in Park. I tried D and it felt like it took alot of gas to make it move. Once I got to my buddies place, I shut the truck off and restarted, and we drive around for 45 minutes and it didn't do it, it drove likes its always done. So I am really confused.

Truck has 212,000km on it, I have a pcm4less tune with shift firmness 2, I have a driveline clunk thats bin there since the day I got it. (5 years now) I dropped the trans pan last winter and followed may05lt's video. Fluid looks good, smells sweet, no more smoke any other time iv checked it.
I got a dash cam video of the first time it happened, I'll post it right away, I gotta cut out all my bad music, and me calling my dad. I got loud exhaust so you can hear the engine noise change.

I don't really know what to do other then ask here, and take it to a transmission shop.

 

[aaronbtb]

 

[littleblazer]

When you pulled over and were braking, did it feel like it was fighting you to stop, like it wanted to keep going?

 

[aaronbtb]

Only time I touched the brakes was to put it in park, it slowed down like that all on its own. I was fighting to keep it going till I turned right. Once I turned I never touched the brakes. After I pulled away I was pumping my brakes to see if they where sticking. I don't know what you mean by "fighting you to stop, like it wanted to keep going".

 

[littleblazer]

Okay so it stopped itself, power drop and you had to keep it rolling. That's strange to say the least... I have no clue.

 

[Mooseman]

Maybe an actuator or accumulator sticking? Very strange indeed.

 

[Camdo]

White smoke coming out of the transmission dip stick tube is the smoking gun. Something inside your transmission got very hot to make smoke from oil, such as a bearing seizure, fusion or bind. Because the vehicle engine bogged down, I could theorize that a band or clutch was operative when it should not have been, creating a ratio lockup.

An automatic transmission is a combination of constantly meshing gears consisting of a sun gear surrounded by planetary gears harnessed in a cage and a ring gear enveloping the planetaries. If one of the three elements is locked (ie. prevented from spinning), power will transmit thru the other two. If none are locked, there is no power transmission, and if two are locked, the system is bound, locked or seized and nothing spins. Only one of the 3 elements can be locked at any one time. Element locking is accomplished with bands (usually on the ring gear) and clutches (usually on the planetary cage) motioned by actuators. The automatic shift is done with a fluid computer (possibly electronic nowadays) that activates the band and clutch actuator. One planetary set can produce two transmission ratios. To get more ratios in like in a 4 speed automatic, several planetary sets feeding into each other are used. So there can be many bands and clutches. All of which must engage and disengage in coordinated fashion or else a planetary set will bind and smoke the oil from the heat generated by the bands and clutches slipping during the bind.

For your problem, I would look with a Tech 2 at the automatic transmission shifting actuators, and exorcise them manually to see if one is sticking. I think too that an actuator history can get attained with the Tech 2 although I am not sure of this. If so, you can see if an actuator was engaged when it should not have been. You might also get some clues by manually shifting to produce the problem and narrow the possibilities by deduction.

 

[aaronbtb]

Thanks Camdo, I'm very uneducated by how a transmission works, trying to understand it gives me a head ache. Today on the highway it drove weird, felt jerky like driving against wind. I think I'm gonna park it for awhile and save up till I can fix it. It still drives, but I don't want it crapping out completely.
Nearest transmission shop is only 15km away but I don't wanna risk it braking down especially when I can't afford to fix it.

 

[TollKeeper]

If you replace the trans, you could always upgrade to the 6L80 trans. There's a guy here in Denver that sells it as a kit. Wiring harness and trans.

 

[aaronbtb]

I have not had any issues since. Its so weird, it drives fine again. Seems a little under powered, but shifts the same, doesn't feel like its shuddering or slipping. I'm worried that a transmission shop wont find anything wrong with it now.

 

[BlazingTrails]

White smoke coming from the transmission usually means water is in there. I'm thinking your radiator is leaking into the trans cooler. If the transmission was that hot you would be able to smell it badly. sounds like steam to me.

 

[RedEnvoyDenali]

if the internal cooler in the radiator is leaking you can usually see the tranny oil film floating on the rad coolant after taking off the rad cap.
if you find this has happened you need to change both the tranny fluid and rad coolant AFTER fixing the cooler or disconnecting it from the system by doing a bypass to an external cooler. Pics of various internal rad tranny coolers

 

[Mooseman]

I would just bypass to an external. They are much more efficient anyway.

 

[aaronbtb]

Coolant looks fine, no foam. I didn't want a external trans cooler because I don't tow, its cold here 9 months of the year. I did take it to a transmission shop and they found no issues. Its bin driving fine, so I'll drive it till it dies.