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GM opens official investigation into C8 Corvette transmission leaks

In March 2020, a month after Chevrolet began customer deliveries of the 2020 C8 Corvette, a GM dealer technician created a Reddit thread about a leaking gearbox in a Corvette with 32 miles. That car hadn't even been sold yet. Since then, as a search of "C8 Corvette transmission leak" shows, it's been tales of woe for some owners. Something in the Tremec TR-9080 transaxle in the back of the mid-engined Corvette doesn't work as it should, the fault able to cause codes that the transmission needs service, or that the driver needs to shift to park. In some cases, the battery would die because of follow-on issues after the initial transmission code, that code preventing the car from powering down. As Autoevolution reports, GM filed paperwork with the National Highway Traffic Safety Administration in August to look into what's going on. Between forum threads and GM's investigation document, there are several issues mentioned. The most common appears to be the dual-clutch transmission leaking fluid due to gasket failures like the one suffered by one owner at 858 miles, and another for an owner currently enduring a second leaking transmission. The Midengined Corvette Forum reported that Chevy engineers redesigned the TR-9080 pan, fitting Corvettes with the new unit at some point in the 2021 model year. The original pan was stamped steel unit affixed to the engine with two studs and 13 bolts, plus "reinforcement plates." The updated pan is said to be a cast aluminum unit affixed with two studs and 17 bolts, omits the reinforcement plates, and gets a new machined new groove around its edge to seat the gasket seal. The GM paperwork now at the NHTSA mentions a P1789 code, and says one reason for it could be "debris on the park position sensor magnet causing an incorrect position reading to the TCM." This might be caused by another issue mentioned in forums, which is clogged transmission filters. GM gives instructions for returning transmission filters to the company, and a poster on one forum said the Corvette tech at the dealer where he bought his Corvette told him the automaker "requires every used transmission filter to be returned to GM."  Whatever's going on, the problems haven't stopped, and they go beyond the P1789 code. Over the weekend, a 2022 Corvette owner posted on Corvette Forums that he got a check engine light on his car after just 850 miles.

Cadillac CT6 production ceases January 2020 as part of D-Ham layoffs

General Motors filed paperwork under the Worker Adjustment and Retraining Notification Act with Michigan's Department of Labor and Economic Opportunity this week, detailing events to come at the automaker's Detroit-Hamtramck Assembly Plant. Starting February 28, 814 salaried and hourly workers at D-Ham, as its called, will be laid off. The 753 workers represented by the UAW will begin receiving offers in January to relocate to facilities in Michigan and Ohio, or buyout offers. As the 4-million-square-foot plant winds down through April 3 to a skeleton crew, the Cadillac CT6 ceases production in January 2020, and the last Chevrolet Impala comes off the line on February 28. The loss of the CT6 represents the end of Cadillac's latest brief, and highly regarded, adventure into flagship sedans. It might also mean the end of the 4.2-liter Blackwing twin-turbo V8 engine, at least for the moment. Both casualties are calamities. The death of the Impala closes the door on a nameplate in production for 52 years since 1957, having started off as a top-tier trim for the 1958 Bel Air known as the Bel Air Impala, once advertised with the line, "Lets you know you're the boss." As part of the new four-year labor agreement with the UAW, GM is keeping D-Ham open to build a new line of battery-electric vehicles, ultimately investing $3 billion and tripling employment to 2,225 workers when fully operational. The agreement described the coming EV as a "van" that would commence production in late 2021, but various reports say what's actually coming is a range of premium EVs in pickup and SUV bodystyles under the program codename BT1. The easy predictions put an electric GMC Sierra and Cadillac Escalade among the EV fold, but not until 2023, according to auto industry forecaster LMC Automotive. Before that, LMC claims an electric van will debut in late 2021, along with a battery-powered rebirth of the Hummer brand in pickup and SUV forms, also in late 2021. 

GM delays 3.0-liter Duramax diesel in Silverado and Sierra pickups

Stricter testing protocols around the world are making it harder for automakers to predict launch timelines. GM is the latest to get caught in emissions nettles, the Detroit carmaker forced to delay the launch of its new Duramax 3.0-liter inline-six diesel for the Chevrolet Silverado 1500 and GMC Sierra 1500. That's what company reps told dealers in a memo seen by Automotive News this week. Dealers and buyers had been promised the Flint, Mich.-built oil-burner in early 2019, but AN wrote that the EPA certification hiccup has turned into a "slight delay." A GM spokesman told Motor1, "[We] did not attribute [the delay] to a single entity, as the truth is this is a collaborative effort between GM and several government entities. We will make the 2020MY Duramax available for dealers orders soon, and expect to deliver the first trucks to customers soon after emissions testing is complete." We know the new 3.0-liter Duramax diesel has 277 horsepower and 460 pound-feet of torque, outdoing Ford's 3.0-liter PowerStroke diesel by 27 hp and 20 lb-ft. But without final EPA paperwork, GM can't release the numbers that will show how the two engines stack up when considering fuel economy and tow ratings. The certification process has been sticky for a few other makers of late, especially since the Volkswagen Group situation in 2015. BMW had to delay the launch of four diesel models in 2016 over EPA testing. The new Ram 1500 dribbled out in a trickle last year for reasons thought to deal with EPA testing, coming as it did a year after the EPA investigated Ram's EcoDiesel engines in 2017 and 2018. More recently, WLTP testing in Europe caught out just about every automaker over there. Since we're almost halfway through 2019, the delay until the 2020 model year is only a few months. Still, GM told dealers to cancel any orders for the engine for this model year. Dealers will need to resubmit the orders once opening begins, but GM hasn't said when production will begin other than "soon." The company said that it will offer 2020-model-year replacement vehicles to customers and dealers. If prices hold into the next model year, the 2020 Silverado 1500 and Sierra 1500 with the inline-six diesel will come at a $3,890 premium over the 2.7-liter turbo four-cylinder, and a $2,495 premium over the 5.3-liter V8.