What Are The Best Gm Connecting Rod Bearing For The Money
A manufacturing error has left a handful of General Motors cars needing new engines with just a few thousand miles on the odometer. The problem came to Car and Driver's attention when three cars—two 2014 Chevrolet Malibus and a 2014 Buick Regal GS—driven by three different editors adult the telltale clatter of a failed connecting-rod begetting during our performance testing.
The feel isn't limited to our drivers, either. Todd Pawlik, principal engineer for GM'southward mid- and full-size cars, told C/D that about thirty customers also have experienced engine failures. Those owners all received new engines under GM's five-year, 100,000-mile powertrain warranty. The affected engines—GM'southward naturally aspirated two.v-liter 4-cylinder and 2.0-liter turbo 4—are used in in the 2013 and 2014 Chevrolet Malibu, the 2014 Chevrolet Impala, the 2014 Buick Royal, the 2013 and 2014 Cadillac ATS, and the 2014 Cadillac CTS. Those models sell at a rate of roughly 35,000 cars per calendar month, including variants with unaffected powertrains.
The failures, according to GM, are caused by bad connecting-rod bearings that slipped by quality control at an unidentified supplier in June 2013. The flawed bearings tin disrupt the oil picture between the bearing and the crankshaft, leading to catastrophic metal-on-metallic contact. "All engines now are designed to microns [0.00004 inch]," said Pawlik. "If the oil motion-picture show isn't consistent, bad things tin happen."
In this case, the consequence is a spun rod bearing that scores the crankshaft and introduces metallic shavings into the oil supply. While it's possible to salve an engine with a spun rod bearing, the difficulty of matching the original tolerances means it'southward far more common to replace the engine.
Full general Motors has no intention of issuing a call up. For ane, the company has no way of knowing which cars carry the faulty bearings. While the assembly institute records which engine is installed in each auto, there is no provision for tracking which bearings are installed in each engine. Pawlik too describes the issue as a "self-declaring" problem, because all failures are expected to occur inside the first few g miles of driving. A spun rod begetting is unlikely to go unnoticed past drivers as information technology produces a prominent, knocking clatter, particularly under acceleration.
GM likewise examined cars that were still on dealership lots, awaiting shipment at the assembly plant, or in transit, past putting them through a stress test that involves hard dispatch and revving the engine to high rpm. While Pawlik wouldn't reveal how many failures were provoked with that testing, he quantified the total number of engine replacements as "ane or two per 1000 cars."
In the wake of the engine failures, engineers accept as well revised the rev limiter on Malibus with the naturally aspirated 2.5-liter engine due to what Pawlik describes as a "hypersensitivity to oil-moving picture thickness." In transmission mode, the rev limiter has been reduced from 7000 to 6700 rpm. "We are fully validated to 7000 rpm, nosotros just saw this as an opportunity to meliorate our robustness," he said. There is no plan to flash customer cars with the lower rev limit as the change has no effect on fuel economy or performance. Auto and Driver's testing has shown that the two.five-liter four-cylinder is quickest in automated mode, where the manual shifts at approximately 6200 rpm.
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Source: https://www.caranddriver.com/news/a15368085/maliboom-faulty-connecting-rod-bearing-causing-engine-failures-in-gm-four-cylinders/
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