Torque Converter or Trans? Whats you're bet? 2016 Tahoe 6L80

[Tiredmechanic23]

So back 3 years or so ago and 90K miles ago my stock converter did its thing and took a crap and I lost everything but 1st and 2nd. Now I have a full built trans from TK performance and a billet 4 carbon fiber clutch converter that I have really beat on for the last 90K miles. The tahoe has a TCM and engine tune via Blackbear and a autocal. It has other minor engine mods which they tuned for. I drive this thing like a vette most of the time and have hurt feelings when I can and still trusted it to go anywhere. As of last week though it started randomly throwing a CEL and losing lockup in 6th. Id be cruising uphill on the highway at say 60mph and you would feel the trans give a slight hicup and the rpms would jump to about 3k and id get a CEL. Codes was always for converter clutch stuck open (P0741) if I remember correctly. Everytime it happened I could clear the code and continue on my way. Then randomly the trans developed a light whine. This entire time it shifted 1-6 just fine with no slip no matter the load. Suddenly though today while driving home from my sons practice while running about 60mph there was a hicup from the trans then it was all neutral except for park and the whine is much much louder.

Onto a few important details. When the first failure happend on the stock setup the pan was full of gold and it was a converter only failure and 1st and 2nd were the only gears I had besides reverse. TKPerformance confirmed this up on teardown and offered to refund me the build price and just charge to do a cleanout as the clutches and all were fine in the trans itself. I opted to build for performance though as I had mods planned out. This built was the max tier build from TK performance minus the billet planetary option as im not doing launches on a prepped track. It was paired with a PATC converter at 2k stall part "PQ80" on their site. Its a 10 inch billet hand welded converter with 4 carbon fiber clutches. At the time it was the best you could buy for this trans. Its had service done every 30k with filter and fluid. The most recent service was about a month ago and the pan was clean and the fluid looked good and smelled fine. The filter did have some gold in it though making think I had some converter wear going on but I had no signs of issues so was hoping/thinking id be ok still for a bit but to just not be so rough on it for now. I called the converter company (PATC) and asked if they could rebuild/refresh it if need be and planned to have them do so when I could down the vehicle hopefully after Xmas.

I can get a cheap reman POS converter to get by on to get to work and back for 300 or less and putt around while I get my nice converter redone. Of course there are cost in a cooler and new filter and fluids and trans clean out but it would get by for a bit.

So whats everyones opinion? Converter took a dump or do we think the trans is dead? Even if its just the converter I plan to get the trans cleaned out and swap to a new cooler again to prevent trash getting into it after repair.

 

[NickTransmissions]

Both.

Sounds like 4-5-6 clutch took a dump and/or 4-5-6 hub is breaking in half (whine sound). Rebuild the trans (install a Sonnax 4-5-6 hub for 45 tooth powerglide spec clutches and install the Sonnax 4-5-6 piston kit, 3-5-R hp apply ring, if not already installed (most likely not if you're neutralizing in 6th and hearing whining sounds). Neutral in all gears is front planetary/sun gear failure.

Send the converter out for overhaul. Dont bother with wasting money on a cheap pos converter for now - save that $$$ for other things.

 

[Tiredmechanic23]

Got to get the cheap converter it needs to be on the road. I have work, my wife has work and we have 4 kids to tote around for band and football season. I can have the cheap one at the door within 24 hours of my order and have it in next day.

As far as the trans its a full build for 1k plus HP by TK Performance. Anything and everything that can be done has been including billet shafts/hubs.

While its possible ive lost the sun gear im really hoping not. It has had no reason to go to shit as I dont launch thing thing. Ive had 0 issues with shifts or slip and only with lock up. And on the fluid and filter change not long ago there was some gold in the filter. Last failure before the build was almost the exact same symptoms and well that was a converter only failure. I went ahead and had it built though since it was all out of the vehicle.

Either way ill know more sunday when I can tear into it and run a few test. im prepared for worst case.

 

[NickTransmissions]

Got to get the cheap converter it needs to be on the road. I have work, my wife has work and we have 4 kids to tote around for band and football season. I can have the cheap one at the door within 24 hours of my order and have it in next day.

As far as the trans its a full build for 1k plus HP by TK Performance. Anything and everything that can be done has been including billet shafts/hubs.

While its possible ive lost the sun gear im really hoping not. It has had no reason to go to shit as I dont launch thing thing. Ive had 0 issues with shifts or slip and only with lock up. And on the fluid and filter change not long ago there was some gold in the filter. Last failure before the build was almost the exact same symptoms and well that was a converter only failure. I went ahead and had it built though since it was all out of the vehicle.

Either way ill know more sunday when I can tear into it and run a few test. im prepared for worst case.

You mentioned going into neutral and im only going by what you've relayed. here's your quote:

Suddenly though today while driving home from my sons practice while running about 60mph there was a hicup from the trans then it was all neutral except for park and the whine is much much louder.
Also this:
Now I have a full built trans from TK performance and a billet 4 carbon fiber clutch converter that I have really beat on for the last 90K miles

So is that an not an accurate recollection and description of how you've been using the vehicle and what occurred when driving home from your son's practice?

You shouldn't be losing the converter either in 90k but it happens so wouldnt surprise me if one or more hard parts are going south..."False neutral can be a few diff things:

- Torque converter - complete and total catastrophic failure, and not just of the clutch - stator, bearings, pump side, etc

- TEHCM or IMS (were these replaced with OEM new parts in the last rebuild)? IMS failure typically throws an IMS code and puts the trans in limp unless channel N that goes direct to the ecm fails then you wont be able to start the truck (no crank/no start).

- Front planet/sun gear beginning to break up

- 2-6 clutch and 4-5-6 clutch slipping to neutral while in 6th gear

Gold in the filter is likely normal bushing wear from trans and TC

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Do you have an itemized invoice of everything that was installed/done?

Do you have a bidirectional scan tool so you can monitor trans and TC live data while driving around?

Did you flip the pill or run a delete kit for your thermal bypass valve?
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Drop the pan and post back as to what you see (shoot a pic or two and include that as well).

 

[CMoore711]

@Tiredmechanic23 are you located in Ohio? Are you talking about TK Performance in Moraine, OH?

 

[Tiredmechanic23]

@Tiredmechanic23 are you located in Ohio? Are you talking about TK Performance in Moraine, OH?

I cant remember the exact city but it was in Ohio yes. I am in Alabama. I freighted it to them for building.

 

[Tiredmechanic23]

No clue why it loaded a blank quote but whatever, the description of what was going on at the time of failure was accurate. The beating on for 90K miles does not mean that every single drive was balls to the wall with a neutral drop or power braking... Again I do not launch it my running and flogging is when im already moving either on the interstate or back roads. Its also never pushed until trans temps are at least at 140.

Everything in the trans was redone. I used TK Performance as they have built record setting cars and do a ton with GM transmissions in the performance world. I no longer have the itemized list but pretty much everything in the trans was gone through and replaced. Planet was replaced with a new stock unit. Original failure the first time was a TC only failure at 90K. Builder offered to refun the build cost and just clean everything out as clutches and all were still spotless. I opted to continue the build as I plan more for the vehicle over time.

The pan was down not very long ago, as I said maybe a month. Magnet was clean, fluid was clean. Filter had a bit of gold and what looked to be worn carbon fiber like material.

The pan will be down tomorrow for further inspection after I do look at it with a scan tool. I have a Solus Plus that will read all I need it to. I have no trans code other than the failed lock up.

And while it may be more than TC, still at this time based on complete lack of any other codes, it failed when the TC attempted lockup, the material in filter at time of last pan drop, lack of any shift issues or slip before failure, etc I am leaning towards catastrophic converter failure.

Either way im not arguing with you on it just giving my opinion on it based on previous experiances. You are giving yours which I did ask for in the originial post. In the end we will see what is wrong and it is what it is. Like I said im preparred for worst case but im feeling its a TC failure. Granted even if its just catastrophic TC failure the rest needs pulled down to clean debris out and inspect.

But ill know more tomorrow (sunday) as its my only day not dealing with the kids competitions or anything else. I do know ill be fixing it ASAP as im stuck driving my 22 2500 6.6 and it is not gentle with its drinking habbits.

 

[NickTransmissions]

No clue why it loaded a blank quote but whatever, the description of what was going on at the time of failure was accurate. The beating on for 90K miles does not mean that every single drive was balls to the wall with a neutral drop or power braking... Again I do not launch it my running and flogging is when im already moving either on the interstate or back roads. Its also never pushed until trans temps are at least at 140.

Everything in the trans was redone. I used TK Performance as they have built record setting cars and do a ton with GM transmissions in the performance world. I no longer have the itemized list but pretty much everything in the trans was gone through and replaced. Planet was replaced with a new stock unit. Original failure the first time was a TC only failure at 90K. Builder offered to refun the build cost and just clean everything out as clutches and all were still spotless. I opted to continue the build as I plan more for the vehicle over time.

The pan was down not very long ago, as I said maybe a month. Magnet was clean, fluid was clean. Filter had a bit of gold and what looked to be worn carbon fiber like material.

The pan will be down tomorrow for further inspection after I do look at it with a scan tool. I have a Solus Plus that will read all I need it to. I have no trans code other than the failed lock up.

And while it may be more than TC, still at this time based on complete lack of any other codes, it failed when the TC attempted lockup, the material in filter at time of last pan drop, lack of any shift issues or slip before failure, etc I am leaning towards catastrophic converter failure.

Either way im not arguing with you on it just giving my opinion on it based on previous experiances. You are giving yours which I did ask for in the originial post. In the end we will see what is wrong and it is what it is. Like I said im preparred for worst case but im feeling its a TC failure. Granted even if its just catastrophic TC failure the rest needs pulled down to clean debris out and inspect.

But ill know more tomorrow (sunday) as its my only day not dealing with the kids competitions or anything else. I do know ill be fixing it ASAP as im stuck driving my 22 2500 6.6 and it is not gentle with its drinking habbits.

If it's neutralizing while it's supposed to be in gear, there's something wrong. Its either electronic/electrical or mechanical (trans and/or tc). But since you're already prepared to have it gone through if necessary, I wouldn't worry about it at this point. Nor am I implying TK didnt do something right; once a certain power level combined with hp usage pattern threhsold is reached, the transmission becomes more like a mainetnance item that has to be rebuilt periodically, no matter who built it or what was done (part upgrades, mods procedures, etc).

Let us know what you find when you do your tests and inspection.

 

[Tiredmechanic23]

Images are not wanting to upload. Ill edit with a link once I get them up elsewhere.

Pan images

Got the pan down today and the scanner on it before hand. Only have a P0872 code stored at the moment and I was seeing 0 pressure on trans PIDs. Pan and was clean and fluid is nice and red but some suspended fine black particulate. Nothing ferrous or any kind of metal in the pan. Pretty sure the black power stuff being as black as it is, is from the CF clutches in the converter. The lack of any metal of any kind is a bit odd. But other than the black powder material thats in the fluid its a healthy looking pan. Its certainly possible for it to be electronic but id figure there would be more codes associated with electronic failure.

We will see what can be figure out. The whine is 100% in the converter only.

 

[Tiredmechanic23]

Forgot to update this thread, but it was in fact the converter that failed. Hub cracked out and the splines stripped which would explain the horrible whining metal noise. Screenshot attached for proof. I did go ahead and have the trans refreshed since it had 100k on the build but everything in it looked good except some pump wear.