If you’re reading this, you're probably considering purchasing (or currently own) a Ford Motor Company vehicle with the longitudinally mounted second-generation 3.5L EcoBoost V6 engine. If you want to learn more about a notorious start-up rattling noise, keep reading.
What is the 3.5L EcoBoost engine? The longitudinal 3.5 liter EcoBoost engine was first introduced in the 2011 Ford F-150 and modified for the 2017 model year. The modified design features dual injection, revised VCT and cam phaser components (which I will be talking about in this article), improved turbochargers, a new timing chain design, and other tweaks in an attempt to address previous flaws the first-gen had. First introduced for the 2010 model year Lincoln MKS, MKT, and Ford Flex and Taurus, the 3.5L EcoBoost V6 engine, whether used in longitudinal or transverse applications, is heavily derived from the Ford Duratec 35 engine and uses the same block and overall design. In simplistic terms, the 3.5L EcoBoost is a Duratec 35 with two turbochargers affixed. The transverse 3.5L EcoBoost powers vehicles such as the Ford Taurus, Flex, Explorer, Lincoln MKS, and MKT (some of these models are no longer produced). There are few differences between first-gen longitudinal 3.5L and first-gen transverse 3.5L, but the most notable is the water pump design. The transverse version uses an internal, timing chain-driven water pump, just like the transverse naturally aspirated Duratec 35, while the longitudinal variant is external for both generations. The second-gen 3.5L is found in the 2017+ Ford F150 and Raptor, 2018+ Expedition, and 2018+ Lincoln Navigator. The Ford Raptor and Lincoln Navigator use the same engine as the F-150 and Expedition but are higher output and gain an increase in horsepower and torque. What is the issue? Despite their known design flaws and quirks, these engines have the potential to be reliable. You can find many instances of used first-gens for sale with more than 100,000 miles or 200,000 miles. At one point, I came across a first-gen in an F-150 with more than 300,000 miles. Though the engine at heart may be reliable, a trending flaw with the second-gen is its redesigned cam phasers which rattle upon cold startup. The 3.5L EcoBoost is known for having several rattles. The first-gen has some issues with cam phasers, but timing chain stretch was primarily known. Cam phasers are a component of Ford’s Twin Independent Variable Camshaft Timing, or TI-VCT. An alternate name for this widely used technology found in most modern cars produced today is Variable Valve Timing (VVT). This technology constantly adjusts the timing of the intake and exhaust camshaft valves for optimal performance and fuel economy determined by current driving circumstances. Oil pressure drives this change in valve timing. With the second-gen, cam phaser rattling is commonplace. This rattle’s general cause appears to be the lack of initial oil pressure feeding the VCT before starting. Sometimes this rattling can be caused by the oil filter not having an anti-drain back design to prevent all the oil from draining into the crankcase, but that doesn’t solve the issue in this case. The issue stems from the cam phaser design itself relating to a pin designed to lock into place after the engine shuts off. However, this pin will not always lock into place, so the phasers spin freely before enough oil pressure has been generated, thus causing a rattle. What should I do if I own or want to buy a vehicle that has this engine? Several TSBs have been issued informing service departments recommending replacing all four cam phasers, including other timing components. The problem, however, is after completion of this repair, sometimes the same rattle reappears over time, though this seems to be less frequent as time has gone on, and Ford has continued to make gradual changes to the phaser design based on the component's part number. There are also TSBs calling for reprogramming the vehicle’s powertrain control module, which controls the cam phasers, but this will rarely, if ever, solve the problem. In fact, it may even make the problem worse. At one point, a TSB issued a while ago caused major transmission shifting problems that were not present prior. Since then, a newer TSB has been issued to address the additional problem the first TSB caused. If you decide not to change the phasers, there is one thing you can try to lessen the rattle severity, and it’s cranking the engine longer. If your F-150, Expedition, or Navigator has the push-button start ignition design, depress and hold both the brake and gas pedal and push the start button. The engine will continue to crank as long as your foot is depressing both. Once you let off the gas but continue depressing the brake, the engine will automatically start. Should I buy a vehicle with this engine? When I first wrote this article in June 2021, I have mixed feelings about this engine. I own a 2018 F-150 with the second-gen 3.5L which currently has 32,000 miles, and it has been reliable thus far despite the cam phaser rattle, though other quirks are present. This April, I finally had the phasers changed per Customer Satisfaction Program 21N03 after having the 21B10 reprogram. The 21B10 did not fix the rattle at all. Shortly after the reprogram was performed, I noticed a more significant hot idle knock resembling a diesel that I've never experienced before, so it made things worse. I'm pleased to say, though, that after having the 21N03 performed, the rattle is completely gone. When looking to buy a Ford or Lincoln vehicle with the second-gen 3.5L EcoBoost V6, pay close attention to the noises it makes when it first starts. Starting the engine when it’s cold is the best way to determine the severity of the rattle. Even better, ensure it has not run for several days. When it’s already warm, starting the engine will not allow you to hear the rattle because not all the oil has drained back into the crankcase, so the oil has already quieted the cam phasers. If you own this engine, it’s most likely not a question of if cam phaser rattle will develop, but when. If the cam phasers are severely worn, you will hear a hear a knocking sound, imitating the noise a diesel engine makes, despite the EcoBoost being a gasoline-only engine. This diesel-like noise will become more pronounced as the engine reaches operating temperature and at idle. If these symptoms are present when you are considering a vehicle with this engine, know that the phasers are worn and they should be replaced. I highly recommend you research information about the 21N03 and 21B10 and read the dates at which these need to be performed to prevent having to come out of pocket for the repairs. Having the 21B10 performed is required before Ford will qualify you for the 21N03. As with knocking, it's worth mentioning I stumbled across a video on YouTube where a mechanic diagnoses a second-gen 3.5L on a 2017 F-150 which sounded like a diesel, only the cam phasers were already replaced according to him. In short, the cause of the noise resulted from severe piston scoring and scoring of the cylinder wall, which created a gap and allowed the cylinder to move side to side. This unintended movement likely damaged crankshaft components also. Unfortunately for the owner, the piston scoring required the engine to be rebuilt, a repair that costs thousands of dollars if the truck’s warranty expired. This is the very first report I have come across of a second-gen 3.5L suffering from scoring. After learning about this, this now leads me to believe bad cam phasers may not entirely cause this diesel-like noise, but instead scoring could be occurring, which is a serious problem that will ruin the entire engine eventually. I’m not sure if this scoring results from a latent design defect these engines have, but I will continue to research this. Opinion Before purchasing my current 2018 F-150 with 20,000 miles at the time, I looked at another 2018 with 35,000 miles at a Ford dealership. The start-up rattle was what I consider extreme, and the engine only sounded worse the longer it ran. The engine performed well during the test drive, but the clattering and knocking once it reached operating temperature reminded me of a Cummins engine. Upon test driving the F-150 I ended up buying from another dealership up north, the engine was whisper quiet and sounded nothing like a diesel. Both are the same engine, yet their difference in sound is night and day. If I were the dealer selling the first F-150 I drove, I’d be embarrassed to present a vehicle that sounded like that to customers. And quite frankly, shame on the dealership. They should have had it fixed before offering it for sale, but that would only cost them time and money, and they would rather have the owner deal with the problem. It’s also worth mentioning that Ford has had a long track record of cam phaser and timing chain problems with their vehicles, especially with the Modular V8 engine series named Triton. Most notably, the infamous 4.6L and 5.4L 3-valve variants are plagued with these issues beginning in 2004. Eventually, the 5.0L Coyote V8 has replaced the Triton engine, but it too has its own set of problems; some I would consider even worse. To be fair, many cases of timing issues Triton engines had were the result of owners not changing the oil often enough, and many of these engines, whether the 4.6L or 5.4L, have surpassed 300,000 miles with proper maintenance. But again, there are instances of owners still experiencing these issues despite frequently changing the oil. Additional resources Below is a video I've made and a thread I’ve created on F-150 EcoBoost forums about this diesel-like noise (including a video I recorded). Since this article's publish date a year ago, I've also created videos more about this engine I recommend prospective buyers and owners watch. Here's the link to my YouTube channel. Experimenting with different cranking times to eliminate start up rattle - my YouTube 2nd gen 3.5L EcoBoost Sounding Like a Diesel - F-150 EcoBoost Forums Now you know the truth behind Ford’s second-generation 3.5L EcoBoost V6 engine and its notorious start-up rattle. I hope you have found this information informative and helpful. Still have questions or comments about this issue? I'd love to help. Feel free to leave them in the comments section below.
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AuthorRyan Emery is an avid automotive enthusiast, researcher, and investigator specializing in defect analysis and recalls. |