Both longtime GM commercial van models, the Chevy Express and GMC Savana, are currently being investigated by the NHTSA in response to five alleged transmission failures.
As Car Complaints reports, the investigation is looking specifically at cutaway Chevy Express and GMC Savana models equipped with the GM Hydra-Matic 6L90 MYD transmission, a six-speed, fuel-saving, electronically controlled automatic transmission for RWD and AWD.
Some evidence is pointing to the possibility that the 6L90 MYD transmission may cause the affected Chevy Express and GMC Savana units to lose power when the transmission is first shifting into “Drive” or “Reverse,” preventing the vehicle from moving.
All affected units are in the cutaway configuration, with Express units from the 2010 through 2018 and 2021 through 2022 model-year ranges. The Chevy Express and GMC Savana cutaway vans from the 2019 and 2020 appear to be unaffected.
GM conducted its own investigation of the issue at the behest of safety authorities and confirmed a defect in two batches of valve body separator plates that were improperly machined during manufacture. The plates wear out the plastic valve body check balls, causing a loss of propulsion.
The NHTSA launched the investigation in part because the Chevy Express and GMC Savana cutaway vans in question are used for ambulances and school buses. GM confirmed to the NHTSA that 1,961 of the vans with the possibly defective 6L90 MYD transmission were completed as small school buses and 89 are in use as ambulances.
Transmission failure in an ambulance, Car Complaints notes, could cause the vehicle to become immobilized while attempting to carry a badly injured or seriously ill person in need of immediate treatment. In the case of cutaways built as small school buses, losing motive power could strand a bus full of children in a dangerous spot, such as on a highway shoulder where it might be struck by other traffic.
GM recently announced the removal of the MYD transmission from several configurations of its 2024 light commercial vans. For both the 2024 Chevy Express and the 2024 GMC Savana, the naturally aspirated 6.6L V8 L8T gasoline engine rated at 401 horsepower and 464 pound-feet of torque – and equipped as standard on 3500 and 4500 series cutaways – will henceforth use the 8-speed heavy-duty automatic transmission (RPO code N8X) instead of the 6-speed MYD transmission.
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Comments
“Transmission failure in an ambulance, Car Complaints notes, could cause the vehicle to become immobilized while attempting to carry a badly injured or seriously ill person in need of immediate treatment. ”
Very true. I am not running defense for General Motors.
Now, do a survey around the US and find out how many Ford-based ambulances are sitting, and have been for months or even well over a year, gathering dust. They and/or their dealers are unable to get replacement parts that should be off-the-shelf items. “Supply chain issues, you know!
How many PowerStroke ambulances have blown their engines on calls?
Not excusing GM either, but if the Feds are going to invoke “Could cause the vehicle to become immobilized while attempting to carry a badly injured or seriously ill person in need of immediate treatment”, at least be consistent about it.
All 6 speed Gm transmission are a huge failure. My 2019 silverado transmission gave up after only 97,000 miles. My brother’s silverado after only 47,000.
Gm should be embarrassed.
mine started having issues after 10k miles…shifts like s#it…Im leasing it and WILL NOT be buying it out or looking for another one.
Is there a difference in MYD used in a cutaway and everything else that used the MYD?
Yes, a transmission failure could be catastrophic for an ambulance or a school bus. But contrary to what many may believe, the preventative maintenance on some of the units operated by “for profit” providers can be deplorable and downright inexcusable. Not to mention the fact that some ambulances and school buses are driven by individuals who could care less about the vehicle in general.
That’s why the transmission should be heavy duty and bulletproof.
Worst part is GM *has* heavy-duty and (mostly) bulletproof with Allison.
Nobody’s going to sweat an additional $500-$1000 in price if it means keeping these vehicles out of the shop.
Sadly it comes down to quality control and Americans have forgotten what that means. Nobody cares about their jobs in today’s America. Just good enough to get a paycheck is all they care about. No pride in workmanship! I have a 6L80 I believe in my 2019 Yukon XL. I hope I get over 100K miles before a rebuild.
Bad gas could immobilize an ambulance, too. Are we going to regulate where ambulances can refuel?
I’m not sure there’s any automatic/CVT transmission in existence that hasn’t had articles about premature failure. Some are worse (4xRE, Nissan-Jatco), some are better (Allison), but all have had issues
I will never buy a GMC again. They were advised by engineers that the transmissions were defected. Read the 2 class action lawsuits that are in progress! Greed! not customer satisfaction is all they care about!
Gmc savana 3500 cutaway 2016 98k went in to have Tran control module replaced at dealership it was purchased at as recalled and Tran flush. Well dealership did not do Tcm recall only tran flush on Tuesday did not respond to calls to find out if was com0leted went to dealership all set $300 and drove away 15 miles and transmission gone all together. Had to tow it to dealership $225, dealership says we will accommodate. Next day go down to dealership they say will have to diagnose it $180 and then we will have to pay for repair. Today they tell my husband it’s going to cost $6k for something that they damaged and no help at all. Do not purchase from Hurd in Johnston ri