Check and make sure you have tranny fluid in it.

:hide:

 

Wow man shitty luck and sorry I don't have insight on the inner working of an auto trans.

 

Does this sound familiar (just happened yesterday to my 2012)?

Driving on the highway today and all of a sudden my truck downshifts. That's odd I think...

So I pull off the highway & when the truck downshifts into 2nd, I hear grinding. Crapola! So I pull over, come to a stop.

Put the transmission into drive. Nothing. Pull ahead in 1st gear. Nothing. But when it shifts to 2nd, metallic grinding. Try reverse for the hell of it... no reverse.

About 2 weeks ago I installed Superior 1-2 & 4th Apply Servos, remote transmission filter, auxiliary cooler, drain plug in trans pan, & temperature sensor in the test port. I have driven it with no problems (other than having to fill the trans as the air is bled from the system, I checked every day until it was stable), including a couple 100+ mile trips.

While I was on the side of the road waiting for the tow truck (3hrs...), I went ahead & checked all my components to make sure they were working correctly. Trans pan was very hot so I disconnected the last fitting just prior to the line going directly back to the transmission and got good flow. Reconnected it & felt the components warm up as trans fluid was circulated around. Checked fluid level, a tad on the high side, but nothing abnormal.

The truck is sitting at the dealer now, waiting an assessment. Googling says to check the sun shell for damage, what do you guys think?

Could my modifications have caused this? If they did, then so be it & I'll eat the repair costs (since warranty won't cover repairs). But if not, I want to be prepared if the dealer accuses the modifications of causing this damage.

Thanks... :th_1j2q1i:

Waiting to hear back from the dealer right now.

 

The sun gear are a common failure in the 4l60e but they sell a 5 pinion setup I believe. Don't quote me because I'm trying to remember back from transmission class.

 

Yes, trans fluid is full, pink, and no metal flake on the stick.

Have got the inspection pulgs pulled off of the bell housing so far, everything looks OK there other than the converter seems to wobble - I think the weld around the seam is just not straight.

I have a guess - I wonder if the filter fell off and the pump is just sucking air? My son is with me today and we're pulling off the pan to take a peek before I have to go pull some money out of my savings account. If it is just the fact that the filter fell off, I should be able to put things back together, get new fluid, and be back in business. Crossing my fingers.

 

Have you done any modifications to it? Any recent work to it? Does anything work if manual go through the gears?

 

No mods, no recent work, no warning - it just quit out of the blue. Nothing other than the slightest bit of a shudder when going into D or R from park or neutral.

Pulled the pan, it looks spotless inside. The filter cannot come off the way it is made - the pan holds the suction tube up inside the transmission body. I am very curious to see what happened inside, especially with the noises it is making.

Going to pick up a used tranny now.

 

Is august national trans take a shit month? Theirs been quite a few go bad here recently.

 

It sounds like Torque converter man. I would pull the coolant line on the drivers side and see if you are getting flow through it.

Also how many miles on your truck and when was the last fluid change?

 

~138K on the truck, not sure when the fluid was changed last but the PO was pretty anal about that stuff. it is probably in the folder of receipts I got with it, but that's in the truck and it is pouring rain right now.

Curious - why do you say you think it is the converter, and what failure mode would describe the symptoms? The noise sounds like it is coming from further back, but that can sometimes be very misleading.

Got the junkyard transmission in the back of my wife's Subaru, will tackle swapping it out with my son tomorrow. I got a new filter, pan gasket, and input shaft seal but two parts stores couldn't come up with the correct output shaft seal. I may just leave that one alone. Still need to pick up transmission fluid. I hope it stops raining because I don't have a garage and I have a dirt driveway.

The parts store had two filters listed - one for a short pan and one for a deep pan. They both are the same height but the filter section is shaped differently. I had no idea which one was correct, so I bought both and will return one.

 

Curious - is the old one worth anything as a core to a rebuilder?

 

Pwt fuse and relay. Have the verter looked at for possible rebuild before install.

 

OK, that's what I was thinking your thoughts were but wanted to make sure.
What failure mode of the converter would cause the pump not to turn, other than the nose of it shearing off? As I recall there are two drive dogs, for lack of a better term, that engage with the pump so whenever the engine is running the pump is turning. That's the way it is on something like a TH350, anyway. I'm not much of a slushbox guy, I prefer to stir my own gears but I couldn't find a decent manual Colorado/Canyon around here to buy when I was shopping. The rest of this truck is in really nice shape so I compromised - and see what it got me?

No CEL.



PWT fuse and relay? I'm guessing PWT = powertrain? Not sure how that would describe the symptoms.
No time to have the converter overhauled before installation, unfortunately. I need my truck on the road by next week. The used transmission came with a converter and it has a 6 month warranty. The counterperson remembered the truck it came out of - it was in a T-bone accident and still yard drove before they pulled it apart.
Worst case, I could always get my original one rebuilt and keep it as a spare, or rebuild with improvements and swap it back in at a later date when I could schedule it.

 

That's why I had indicated to pull the cooler line. Your pump is tied to the torque converter. No converter, no fluid pumping. If fluid was flowing, then you know it's something else. The other reason why I said that is that you said it was a pretty sudden give. You just rev'd up. Kinda like when you blow the clutch in a manual. Same thing. Loss of torque converter will do the same thing. The other possibility is loss of electrical, but I would imagine the CEL would come on at that point.

 

The more I've looked into I think your pump went. It's good you have another converter. It would be bad to use it and have it blow something again. When you swap the tranny in fill it with DexronVI.

 

Your truck you do what you want.

 

Well, nobody has guessed the correct answer as to what happened yet.

It is not electrical, or hydraulic in nature. I have a couple pictures to upload later (still reassembling the truck now) but any further guesses?

 

sounds like either a torque converter or pump , from what you say its as if its not getting fluid pressure

 

transfer case or driveshaft?

 

I'll.say broke the shift cable with it stuck in neutral

 

That would be a good guess as hell.... I dunno if it's not mechanical.

 

I have never seen this mode of failure before. The smaller splined input shaft to the transmission stripped out, and if you look at the pictures the larger one shows signs of abnormal wear as well, though it had not failed yet.

Good splines:

Bad splines:

I didn't get a picture of it, but the mating splines in the torque converter seemed to be in good shape. This leads me to believe that these input shafts were softer than they should have been, and as such were defective parts from the factory that took 138,000 miles to fail. The replacement transmission has the same mileage as my truck does and as you can see from the pictures the splines are in perfect condition. Plus, like I mentioned, I have never seen a transmission fail this way. Bad heat treat or defective steel, I think.

I haven't got the truck all back together yet. The transmission is in but I still need to hook up cooler lines, tighten the torque converter bolts, install shift linkage, etc. then I have the transfer case and driveshafts to replace plus fill fluids but it should be done tomorrow night.
I don't have a garage and I have a dirt driveway which makes work like this tough. Add to that a very strong rainstorm that came through this afternoon and sent a miniature flash flood through my work area, and this job has really sucked so far.

So,
Used transmission: $500
Filter and input shaft seal: $40
2 quarts of Syncromesh: $18
12 quarts of Castrol Dexron VI and a deep 15mm socket: $101
3 days of crappy work so far with my son: Priceless.

 

Did the previous owner seem like the type of person who would abuse the truck? If not, even though the truck is out of warranty, maybe a call to GM (or to the GM rep here on the site) and show them the input shaft. Might be something their engineers would be interested in looking at to see if they could determine a cause.

 

Absolutely not. He was very anal about the truck and went so far as to not sell it to someone he thought would take worse care of it than he thought I would. He has E-mailed me a couple of times just to say hi and see how the truck has been doing.

I'm new here and don't know the GM rep on-site - if someone could send him a link to this thread that would be cool.

 

Looks to me like it was a combination of the spline being machined out of tolerance and a bad heat treat. That's a really strange failure though, I have only heard of similar failures happening on really high horsepower/torque vehicles never on a stock vehicle.

 

:yeahthat: Looks like the splines stripped right off.

 

Damn........

 

Yeah....I just have to say that's completely impressive. That's got to be a shaft that was not hardened. I seriously would not have guessed that. At least you are getting it swapped out.