Why Ford F-150 Cam Phasers Rattle and When to Replace Them
If you own a Ford equipped with the 3.5L EcoBoost engine, you may have experienced a heart-sinking moment during a cold morning start. You turn the key, and for a few brief seconds, the engine emits a loud, metallic clattering sound - often described as the sound of marbles in a tin can.
This cold start rattle is one of the most discussed topics we hear from our customers. Known technically as cam phaser knock, this issue has plagued many 2017-2020 F-150s, as well as Expeditions and Lincoln Navigators fitted with this EcoBoost engine. Understanding why this happens and when it transitions from a nuisance to a mechanical emergency is vital for the longevity of your truck.
Why Do Cam Phasers Fail?
The cam phaser is a sprocket at the end of the camshaft. Its job is to adjust valve timing to optimize performance and fuel economy. To do this, it uses oil pressure to rotate the camshaft relative to the sprocket.
When the engine is off, oil pressure drops. To prevent the phaser from flopping around during the next start-up, a small internal component called a locking pin is supposed to engage, holding the phaser in a fixed 'base' position. In many 3.5L EcoBoost units, this locking pin or its receiving pocket wears out or fails to engage properly.
The infamous cold start rattle is the sound of your timing components struggling to find their footing before oil pressure takes over.
Without the pin locked, the internal vanes of the phaser slap back and forth against the housing until oil pressure builds up enough to stabilize them. This is what causes that distinctive 2-to-5-second rattle upon startup.
Stages Of Failure: Annoyance To Limp Mode
For many owners, the rattle is initially just an annoying noise. At this stage, the truck usually performs fine once the oil pressure stabilizes. However, ignoring the sound is not going to end well.
As the internal damage to the cam phaser progresses, the timing can become offset or advanced beyond the engine computer's ability to compensate. This is when you move into the check engine light stage. Common diagnostic codes include P0011, P0012, or P0016. If the timing deviates too far, the vehicle will enter Limp Mode, significantly reducing power to protect the engine from catastrophic failure.
Ignoring a cam phaser rattle is a race against time; eventually, an annoying sound becomes a dead engine if the timing jumps or components shatter.
The Solution: Ford’s Latest OEM Revision
The best way to resolve this issue is not to buy cheap aftermarket parts, but to invest in the latest revised OEM phasers from Ford. Ford engineers recognized the issue and released an updated version specifically targeting the 3.5L EcoBoost that features a more robust locking pin mechanism and redesigned internal springs.
These updated OEM phasers are designed to prevent rattle recurrence by ensuring the locking pin remains seated even after thousands of heat cycles.
When performing this repair, it is also recommended to replace the following components:
The latest Ford OEM phaser revisions are a 'one-and-done' solution, engineered specifically to fix the design flaws found in earlier 3.5L EcoBoost models.
Can I Replace Cam Phasers Myself?
Yes - you can replace cam phasers yourself, as long as you're a skilled DIYer. You'll need to be comfortable with major engine disassembly, and it helps if you've done timing chain or cylinder head work before. You'll also need to own or can rent engine-specific timing tools and follow factory timing procedures exactly, so be sure you're prepared.
How Much Do Cam Phasers Cost?
OEM cam phaser from Ford typically range from under $100 each to a couple hundred each for some applications. Full replacement kits including timing chains, etc. typically cost $1k-$2k and can vary depending on which components are included.
OEM Ford Cam Phasers From Blue Springs Ford Parts
If your 2017–2020 F-150, Expedition, or Lincoln Navigator is rattling at every startup, turn to Blue Springs Ford Parts for genuine cam phaser replacements. Changing phasers is a labor-intensive job, so using the highest-quality, latest-revision parts is essential to ensure you don’t have to do the work twice.
Blue Springs Ford Parts is one of the largest Ford parts departments in the US. We have decades of experiencef selling wholesale Ford, Lincoln, and Mercury parts, and all our OEM components are backed by Ford's replacement parts warranty. Contact us with any questions, and order your parts today.