It’s well-known that Toyota values quality, durability, and reliability in its vehicles. However, for car enthusiasts, these same attributes often come under scrutiny when the company introduces something new. This scrutiny has been particularly evident over the last two years concerning the V35A-FTS engine, the twin-turbo V6 that has largely replaced the traditional V8s in Toyota’s lineup. Although it may be premature to reach any definitive conclusions, various issues have raised concerns about the QDR (quality, durability, reliability) principles, with no clear solutions apparent thus far.
I’ve been eager to delve into this matter for almost a year, but Tinkerer’s Adventure on YouTube has already taken the lead. They conducted thorough research to highlight the differences in the V35A-FTS, interviewing Lexus GX Chief Engineer Koji Tsukasaki and a seasoned Lexus technician with two decades of experience, in addition to analyzing a comprehensive SAE report on the engine. While these powertrains haven’t been around long enough for clear assessments, this investigation has yielded substantial insights.
Toyotas are famous for their longevity, largely attributed to their overbuilt, low-stressed components. At first glance, a 3.4-liter V6 engine producing 479 lb-ft of torque may seem contrary to this philosophy. Of course, turbochargers play a significant role here, but the complexity within a smaller engine presents challenges—higher pressure, increased fuel consumption, and more overall activity. When you compare it to the older 4.6-liter naturally aspirated V8 in the Lexus GX460, the displacement per cylinder is almost identical. Nevertheless, there are some substantial differences in the engine’s construction.
A key distinction of the V35A-FTS is that it is under-square, featuring a 100mm stroke that surpasses its 86mm bore. This design is believed to enhance low-end torque compared to over-square engines, like the 1UR-FE V8, which had an 83mm stroke paired with a 94mm bore. Tsukasaki points out that this configuration contributes to the V6’s impressive torque output of 479 lb-ft, a notable increase over the V8’s 329 lb-ft—representing a 46% advantage.
There exists a genuine worry that engines exhibiting high specific power output, meaning horsepower per liter, may experience poor thermal efficiency—often leading to reliability issues. However, Toyota asserts that they have overcome this challenge with a high-speed combustion process featuring optimized intake port angles to improve tumble flow. This advancement aims to create a more effective air-fuel mixture and reduce energy losses, essentially offering an optimal balance between specific power output and high thermal efficiency with this V6.
Despite this, the reason behind the main bearing failures seen in some of these engines remains unexplained. Tinkerer’s Adventure consulted with Chris Gonzales, a veteran Lexus technician who owns a 200-Series Toyota Land Cruiser equipped with the earlier 5.7-liter V8. He noted that throughout his 20 years working on Lexus vehicles, he has encountered main bearing problems in only three cases—all involving LX600s utilizing the V35A-FTS. This issue has also surfaced in Toyota Tundra pickups, as experienced by a Reddit user u/myoung34, along with others commenting on similar experiences.
The SAE documentation reviewed by Tinkerer’s Adventure reveals that the V35A-FTS is equipped with metal overlay bearing liners. In theory, this design should be more robust than the resin liners used in the older V8 and is intended to “support high load and high-speed driving,” according to Toyota. Additionally, while the V8 featured six-bolt main bearing caps, the V6 integrates four-bolt caps into a structure called a ladder frame, which is designed to enhance rigidity and durability.
The root cause of the bearing failures has yet to be conclusively identified. Regardless of the source of the issue, it presents a significant challenge for technicians like Gonzales. In all cases I’ve encountered, Toyota directs dealers to replace the short block while reusing unaffected factory parts. This scenario certainly weighs heavily on owners, especially given the potential downtime and the daunting sight of the engines disassembled.
There haven’t been enough instances to label this as a widespread issue. Moreover, there’s crucial information still missing about factors like owner driving habits, which may play a role in these failures. Nevertheless, this matter is under close observation by technical experts, owners, and prospective buyers alike. I will continue to monitor developments related to this story, and anyone with further information is encouraged to reach out.
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