I recently heard about how prone the torque converters are know to fail on most the full size gm suv and trucks. I’m curious to know if there is anything you can do to prolong the life of the transmission? We have 85000kms on our 2017 yukon, I’m sure we are due for a transmission oil and filter change at the very least
Torque converter issues
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other than changing the fluid and filter very often then you would need to upgrade some internal parts before it fails
@Doubeleive completely agree. I do every 40 to 50k on my 2017 8 speed. Don't even really have to drop the pan. Just have it flushed and keep the fluid clean. I talked to an old timer who's done transmissions for YEARS and he said the filter change really isn't necessary as long as the fluid is kept clean. It's more of a safeguard for big shit that fails and the will hopefully save the small stuff. I've had the filter changed twice and I'm due for another service at 130k. Gonna just flush it and move one.
I do mine annually so less than 20k miles, in fact I do all fluids annually except the rear diff & transfer case those i do every 2-3 years
What transmission do you have (6 or 8 speed)?
Fluid and filter every 24-36k for daily drivers; 12-18k for heavy duty, towing, working beyond the scope of private party ownership patterns.
Failing to change the filters in these six and/or eight speed units can result in increased contamination, them getting partially restricted resulting in inconsistent oil pickup and slippage at WOT.
The six speeds (6L45, 50, 80, 90) are also prone to pump wear on the working surfaces as well as wear in the pressure regulator valve. Keeping up with fluid changes mitigates the associated risks and helps prolong the life of these units.
The eight speeds (8L45/90) have a TSB for TC shudder and harsh 1-2 upshift, primarily due to use of wrong fluid used. Per the link, flushing the trans with mobile 1 synthetic (or presumably any quality full synthetic fluid) helps.
The solenoids (or techm) in between types of transmissions are also very sensitive to contamination, moreso than earlier units like the 4L60e.
Address pattern failures by installing updated parts and performing requisite procedures on overhaul.
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Ours is a 5.3 6 speed. Is this a diy job or better off letting a shop do the flush and filter?
You can do it yourself if you’re reasonably handy though its best to have a helper with you. There’s instructions out on the net for DYI trans flushes. Since you have less than 100k on the vehicle, most shops should be willing to do the flush (many wont once milage tops 100k).
If you are also planning to replace the TECHM then I’d take it to a shop or GM dealer so they can do the flushing as well as acquire, install it and flash/run the adaptive learn on the new TECHM so it controls the trans properly.
Never heard of changing the techm. What exactly is that for?
The GM six speeds all use a transmission control module known as a “TECHM” and it’s responsible for commanding and controlling the trans. It consists of a bunch of solenoids and pressure switches as well as an internal mode switch together in all-in-one unit that informs the pcm which range has been selected on the shifter (Park, Reverse, Neutral, Drive, etc) and then controls shifting, line pressure and other vital functions while the vehicle is running and moving.
Here’s a quick overview.
So the techm needs to be replaced every once in a while or the new ones are different then the stock ones? Sorry for all the questions and appreciate all the insight !!
Its recommendated that you replace every 100k so id prob have it done so you know its good to go. And for this, id go to the dealership so you know youre getting a genuine GM part and they can do the fast-adapt relearn for you. Don’t want any aftermarket electronics in the vehicle…
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It is GREAT to have a transmission specialist in the Forum!
Interesting. I'm going to call my dealer and ask about this job. Buddy of mine also has a yukon like mine 2017 also and his transmission went out at 180000kms. So this is why I got looking into this.
Absolutely! I wouldnt have known about any of this had he not commented
Yea, see what the service tech recommends insofar as flushing, TCM / TECHM replacement, etc...they may elect to function test and if everything's good, defer replacement which may save you some coin as those things aren't cheap.
Service tech recommended a fluid change only. They don't like to do the filter because of the seal apparently. I feel like I want the filter changed as it never has been. Also would like to add a pan with a drain plug so I can do more regular changes.
And I am also going to change the Thermal bypass valve to the new one so the transmission runs cooler.
Those are all good ideas…the filter pick up seal can be tricky to get to without dropping the control assembly out of the way but that seal usually isnt a problem. That said it may be a liability issue for them if the seal isn’t replaced when doing a filter and perhaps to replace it requires them to drop the control/valve assembly thus adding $$$ to the job. Just a guess…
I’d want to see whats in the pan and how much clutch material may be present as well…
I'll add this, I called my local GM dealer last week to inquire how much a fluid and filter change would cost on my Cadillac CT6 (8 speed), and was kind of scolded for asking that the filter be changed. I was informed by a seasoned service advisor that the filter "is a screen to catch large particles and didn't need to be changed." He stated all I needed to do was flush the system and explained to me that process would get 99% of the fluid where as a filter change wouldn't. What bothered me is that the CT6 owners manual chart for maintenance intervals, normal driving, doesn't have a line item for the transmission. You have to go to the next page/chart for severe driving that then lists the transmission, which states to replace the fluid AND filter at 45k miles, and at every 45k mile intervals.
So be careful what the dealership states.
So be careful what the dealership states.
I've decided to do this myself. I want to see how much filings is in the pan and I want the filter changed. I will use my vacuum pump through the dip stick tube to remove most of the fluid before dropping the pan. I'm thinking I could just use the pump in between filter changes to do a half oil change
Your experience is why I provide my own written maintenance guidance for all my rebuilds, which sometimes significantly deviates from what the dealers call for.
For example, BMW eliminated dipsticks in their transmissions sometime in the last 10-15 years or so and started specifying that transmission fluid was “lifetime”. To BMW: LOL what does that mean? Lifetime of the unit itself between overhauls, expected lifetime of the transmission or vehicle, lifetime of the owner? Unless some chemical science breakthroughs happened with trans fluid recently, it still wears out and needs to be changed after a period of time. And what happens when a filter can no longer “store” crud, debris and other stuff? Does it empty itself and make the debris disappear on its own?
I provide a service interval sheet for such units and directions for how to refill the fluid once the old fluid is emptied, new filter/gasket installed and pan is back on.
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