Is the Twin Turbo 3.4L V6 in the Lexus GX 550 a Reliable Engine?
Many have expressed concerns over the new twin turbo 3.4L V6 in the Lexus GX 500, and as it turns out, those concerns may be warranted.
When the all-new 2024 Lexus GX 550 was unveiled some time ago, it was met with near-universal praise – largely, for the way it looks. This clean-sheet design pulled off a near-impossible feat in today’s world, in fact, by making everyone drop their collective jaws at once. However, there is one detail present in the Lexus GX 550 that did raise eyebrows for a different reason – the SUV dropped its V8 power in favor of the twin turbocharged 3.4L V6, which also made plenty of people wonder whether or not the GX will be able to retain its reputation for being incredibly reliable. Thus, that’s a topic that that the YouTube channel Tinkerer’s Adventure decided to tackle in extreme detail recently.
Toyota’s V35A-FTS powerlant isn’t exactly new, as it. debuted in 2018 a the Lexus LS, and has since been used in the Land Cruiser 300, Tundra, Sequoia, and the LX 600. It actually makes less peak power in the GX 500 than those applications due to its smaller turbochargers, albeit considerably more torque than the outgoing V8, which is by design – this is an off-road vehicle, after all.
Thus, since this is still a relatively new engine, it’s difficult to gather a ton of real-world data in terms of long term reliability – at least right now. However, we can take a look at the V35A-FTS and its many features to gain some clues – starting with concerns that these smaller, turbocharged engines are overstressed with their higher outputs – in terms of output per liter, the new V6 is far higher than previous naturally-aspirated powerplants, though Toyota notes that these engines were developed with the same standards in terms of durability that it always has utilized.
Toyota also points out that combustion efficiency has improved with these new engines, meaning that they make more power with less compression than before, which leads to reduced stress and fatigue. Typically, however, engines like this have lower thermal efficiency, as they must combust far more fuel to make more power, which increases heat and stress on the engine. In this case, Toyota seemingly managed to circumvent that issue thanks to its high combustion efficiency, however.
There are a lot of factors that play into that rather impressive feat of engineering, ranging from optimized intake port angles to expanded valve seat diameters, along with a multitude of other little tweaks. Thus, we’re left to look to the real world for examples of whether or not all this clever engineering will pay off in terms of long-term reliability, and in that regard, our host points out that a friend of his – who has been a Lexus tech for 20 years – recently had a 20k-mile LX 600 come into the shop for a main bearing issue, and there are reports of the same problem with the newer Tundra. In total, he’s had to replace three long blocks over failed main bearings, in fact.
However, it’s currently unclear what might be causing this bearing issue, as we can’t solely blame it on the smaller, forced induction engine putting more stress on that particular part. As our tech notes, it could be a materials issue or something else entirely, and in the case of the vehicles that he has replaced the long block in, they’ve been running perfectly fine ever since. Regardless, Toyota did make a number of updates to the main bearing for this particular engine in an effort to beef it up, and yet, it’s failing at a higher rate with no obvious explanation. Thus, for now at least, the jury is still out on the long-term reliability of the V35A-FTS, though we’ll have to keep a close eye on this main bearing concern.
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