3.5L EcoBoost Cam Phaser Rattle – Symptoms & Fixes

Austin Parsons

Meet Austin

Austin holds a technical writing degree and has 5 years of experience working as a Technical Product Specialist at BMW. He is an avid car enthusiast who is constantly watching F1, consuming automotive content, racing on his simulator, and working on his Toyota’s and BMW’s. Austin’s technical writing skills, extensive automotive knowledge, and hands-on experience make him an excellent resource for our readers.

Since its release in the 2010 Lincoln MKS, the 3.5L EcoBoost has become one of the favored powerhouses in Ford trucks and SUVs. While the Ford 3.5 EcoBoost is one of the most celebrated engines in Ford’s modern engine catalog, it isn’t a stranger to issues. The Gen 1 3.5 Ecoboost suffered from a number of timing and VCT-related issues including timing chain stretch.

Many of the issues with the first gen 3.5 EcoBoost were ironed out with the Gen 2 3.5 EcoBoost. However, 3.5L EcoBoost cam phaser rattle is an issue that carried across the generational change. In this guide, I cover Ford 3.5L EcoBoost cam phaser rattle, symptoms, how to fix it, and what Ford has done to try to remedy the issue.

Image Courtesy of Underhood Service

First Gen 3.5 EcoBoost vs Second Gen Timing Issues

Over the course of the 3.5 EcoBoost’s build cycle, the engine has gone through multiple revisions. In 2017, the Gen 2 3.5 EcoBoost was released in the F150. The original 2010-2017 Ford 3.5 EcoBoost was notorious for having an array of issues, especially with the timing and VCT system. We have already written an article about Gen 1 3.5L EcoBoost timing chain rattle, but the first Gen 3.5 EcoBoost suffered from other timing issues as well, including cam phaser rattle, but not as often as the second-gen.

The second generation 3.5L EcoBoost was released in 2017 with the mission of adding some additional performance-related goodies. It also resolved a number of issues from the previous generation. Most relevant to this article, Ford changed the design of the second gen’s entire cam drive system. While the first generation featured a single primary chain, the second-gen uses a two-chain system which was meant to reduce the timing chain stretch problems on the earlier engines. That was successful, as the Gen 2 3.5 EcoBoost didn’t have the same issue.

Ford also claimed to have fixed the VCT cam phasers on the second-gen 3.5 EcoBoost to a more robust design. That didn’t end up being the case. Cam phaser rattle actually occurred more frequently and at lower mileage on the second-generation engine. We’ll cover exactly what that means in the following section.

It is also important to mention that 2021+ 3.5L EcoBoost Ford models received an updated cylinder head and cam phaser design which has supposedly resolved the cam phaser issue. 

What is 3.5L EcoBoost Cam Phaser Rattle?

3.5L EcoBoost cam phaser rattle, often called startup rattle, is a sound that occurs on startup if your truck has been sitting with the engine off for an extended period of time. Most Ford owners notice cam phaser rattle if their truck has been sitting for more than 2-6 hours. The sound itself is a distinct and loud rattling noise coming from the engine bay as soon as the engine turns over. It typically lasts for a couple of seconds after the engine starts. We’ll insert a sound clip below so you can get a better idea of the sound itself. 

The Ford 3.5 EcoBoost engine is equipped with Ford’s VCT variable camshaft timing system. That allows for better engine performance, reduced emissions, and increased fuel efficiency. The cam phasers play an important role in that system, as they are responsible for adjusting the position of the engine’s camshafts in relation to the crankshaft.

The sound is the result of one, or multiple, VCT camshaft phasers malfunctioning and rotating independently of the camshaft before receiving ample oil pressure. We’ll get into the potential causes of 3.5 EcoBoost cam phaser rattle in detail in the following section. However, it is important to note that the jury is still out in terms of the severity of the 3.5 EcoBoost cam phaser issue. Ford claims that it is just a minor annoyance. Others think that it could be symptomatic of a more serious issue waiting to happen down the line. We’re inclined to believe Ford here, especially considering there aren’t many reports on the contrary.

What Causes Cam Phaser Rattle?

Over the years, there has been quite a bit of speculation as to the underlying cause of 3.5 EcoBoost cam phaser rattle. However, as time has passed, and Ford mechanics have had time to inspect not only the cam phasers but other integral parts of the VCT system, there is a pretty solid consensus at this point. Most Ford techs believe that the EcoBoost startup rattle is caused by inadequate oil pressure reaching the cam phasers on startup. 

That is only part of the issue though. There is also a flaw in the early cam phaser design itself. The cam phasers consist of a few major parts. The most important parts are the internal rotor and the housing that encases the rotor. The blades of the rotor spin between the walls of the housing. The direction and amount that the rotor spins inside the housing is dictated by the oil pressure on either side of the rotor blade. That oil pressure is what allows the phaser to advance and retard timing. Beyond determining the rotor’s position inside the housing, the oil also serves as a buffer between the rotor blades and the walls of the housing.


After a 2-6 hour window with the engine off, all of the oil will have drained from the phasers into the engine. Without any oil, the internal rotor in the phaser makes contact with the housing walls, creating the startup rattle. Ford recognized this as an issue and built a locking pin into the rotor design to prevent it from moving until adequate oil pressure was reached. However, the locking pin frequently fails which is when the 3.5 EcoBoost startup rattle becomes an issue. 

Cam Phaser Rattle Symptoms

  • Loud 2-3 second rattling noise coming from the front of the engine bay

Ultimately, there is only one symptom in reference to 3.5L EcoBoost startup rattle. That is the rattle itself. In most cases, you either have it or you don’t and there aren’t any other accompanying symptoms. While some Ford owners have claimed that the startup rattle has led to more serious drivability issues down the line, there is no evidence that that was caused by the rattle itself. 

Ultimately, the issue is caused by the phaser’s internal components making contact with each other for a few seconds. While it is never good to have metal-on-metal contact inside an engine, the rotor and housing are both robust parts and are self-contained.  

What Models Were Affected?

There have been multiple Ford technical service bulletins released about the 3.5L EcoBoost cam phaser rattle. In these service bulletins, Ford outlines that the following vehicles are affected by the startup rattle:

  • Ford F150 (2017-2020)
  • Ford Expedition (2018-2020)
  • Lincoln Navigator (2018-2020)

It is important to mention that earlier Gen 1 3.5 EcoBoost engines also had cam phaser issues as well. However, cam phaser rattle isn’t nearly as common on earlier engines as it is on the Gen 2 EcoBoost. Along similar lines, earlier 2010-2015 3.5 EcoBoosts suffered from timing chain rattle. Timing chain rattle has a similar sound but is created by a different problem. You can learn more about 3.5L Ecoboost timing chain rattle in our dedicated guide.

Cam Phaser Rattle Fixes

The only way to solve 3.5 EcoBoost cam phaser rattle is to replace the phasers themselves. That is a pretty big job, as the phasers aren’t easily accessible without removing the valve covers and front engine cover. Prior to 2020, Ford was replacing damaged cam phasers with the same defective parts, meaning that they were prone to failure again. Even after a multi-thousand-dollar “fix.” 

While it is generally concluded that replacing all four 3.5 EcoBoost cam phasers is the only way to get rid of the issue at this point, Ford has tried other ways of remedying the issue in the past. As part of Customer Satisfaction Action 21B10, which Ford released in July of 2021, Ford believed that they might be able to solve the startup rattle issue with a PCM update. The update essentially increased the oil pressure of the engine which they thought would get oil to the phasers sooner. In reality, it wasn’t a move to fix already faulty cam phasers but was meant to prevent the issue on trucks that didn’t already have the issue.

In 2020, Ford finally redesigned the 3.5 EcoBoost cam phasers. The new cam phasers have seemed to eliminate the issue for good this time. The redesigned phasers look entirely different from the earlier part. The entire phaser is encased in a new housing and the previously external spring is also enclosed. The locking pin mechanism has also been redesigned, functioning correctly this time around. We’ll include both the old and new 3.5 EcoBoost cam phaser part numbers below.

Old Cam Phaser Part #s:

Intake: HL3Z-6256-CD

Exhaust: HL3Z-6C525-CD

New Cam Phaser Part #s:

Intake: ML3Z-6256-A

Exhaust: ML3Z-6C525-A

Warranty Coverage and Ford Support

Ford has been very aware of the 3.5 EcoBoost cam phaser rattle issue for quite a while at this point. In response to it, they have released a number of technical service bulletins and field service actions to alert Ford mechanics and owners of the issue. Ford released the first TSB in June of 2020 and there have been quite a few since then.

Technical service bulletin 21-2119 outlined the 3.5L cam phaser issue. It stated that the phasers need to be replaced if the issue occurs. That later evolved into Field Service Action 21B10, which called for a PCM update to potentially alleviate the issue. The PCM update didn’t solve the issue for any 3.5L EcoBoost. However, it helped prevent the issue from occurring again once the phasers were replaced. Additionally, Ford outlined that warranty coverage for the phasers would be extended under another Customer Satisfaction Program.

CSP 21N03 was the extension of 21B10 which outlined the conditions under which Ford would replace the phasers under warranty. It essentially stated that Ford would cover 100% of the repair to 69,999 miles, 66% from 70,000-79,999 miles, 33% from 80,000-89,999, and nothing above that mileage. Unfortunately for current 3.5 EcoBoost owners that experience startup rattle, the extended warranty expired in January of this year.

Replacement Cost 

At this point in time, the cam phaser warranty extension outlined in CSP 21N03 has expired. The goes for the other prorated cam phaser repair options outlined in the other Customer Satisfaction Programs as well. Most of those offers expired in January of 2023. That leaves the owner of the vehicle to cover the cost of repairs out of their own pocket. 

As we stated earlier, the cam phaser repair procedure is pretty intensive. At most certified Ford repair facilities, the cab is removed to gain more access to the front of the engine. In most cases, Ford charges around 10 hours for the repair, so that can add up quickly. The most commonly quoted number for a 3.5 EcoBoost cam phaser replacement is $2,500-$3,000. That does include parts and labor but that is a pretty hefty repair bill. 

With that being said, there are ways to replace the cam phasers without removing the cab. It is actually a pretty common DIY repair for Ford owners that have a decent amount of technical experience. The job itself requires only a couple of specialty tools and the cam phasers themselves typically cost around $350 for a set. While it does take a fair bit of time, the DIY route is one way to save on the repair. If you are interested in seeing what the DIY job entails, take a look at the video below. 

Frequently Asked Questions

What is 3.5 EcoBoost cam phaser rattle?

3.5 EcoBoost cam phaser rattle is a loud rattling sound coming from the engine bay on startup. Generally, the sound lasts for around 3-5 seconds after the engine turns over. It usually only happens if the truck has been stationary for more than 2-6 hours. At that point, all of the oil will have drained out of the phasers themselves. The rattle is caused by a failed locking pin inside one or more of the VCT phasers. The failed pin allows the internal rotor to make contact with the phaser housing due to a lack of oil pressure.

Is cam phaser rattle bad on the 3.5L EcoBoost?

According to Ford’s documentation, 3.5L EcoBoost cam phaser rattle does not affect safety, performance, or emissions. For the most part, it seems that phaser rattle is more of an annoyance than anything else. While some 3.5 EB owners have claimed that the rattle had something to do with later problems, no other issues have been attributed to the cam phaser rattle directly.

How much does it cost to fix 3.5L EcoBoost cam phaser rattle?

3.5L EcoBoost timing chain rattle can be a truly expensive problem to fix at a Ford dealer. The average cost for a 3.5L EcoBoost cam phaser replacement is between $2,800 and $3,000. Obviously, that cost can be dramatically reduced if you do the repair yourself. With that being said, it is a difficult repair as the valve covers and front engine cover have to be removed.


There’s no doubt that the 3.5L EcoBoost is a fantastic engine overall. However, some of its most common issues are a deal-killer for some Ford enthusiasts. That is especially true for the numerous timing and VCT-related issues that have plagued the 3.5L EcoBoost, along with other engines in the EcoBoost family, for over a decade. Even after the improvements made to the 3.5 in 2017, cam phaser rattle was even more of an issue on the Gen 2 3.5 EcoBoost.

Cam phaser rattle is a loud rattling noise that occurs in the engine bay after starting the truck following an extended period of inactivity. It is caused by a failure of an internal securing pin in the cam phasers, which allows the rotors to make contact with their housings, resulting in the rattling sound. The failure happens over time due to a lack of oil pressure during startup. Although the cam phaser rattle is not a serious drivability issue, it is a significant annoyance for owners. 

Unfortunately, the only way to get rid of 3.5L EcoBoost startup rattle is to replace the cam phasers. That is unfortunate, as the labor associated with the job is extensive and expensive if performed at a certified Ford repair center. Ford typically charges $2,800-$3,000 to replace all four phasers. With that being said, now is the best time to have the repair done. With the redesigned phasers introduced in 2020, it is unlikely that the issue will return once replaced. That couldn’t be said for 3.5 EcoBoost owners that had their phasers replaced before the redesign.

If you are interested in learning more about other 3.5L EcoBoost problems, take a look at our 4 Most Common 3.5L EcoBoost Problems Guide.

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  1. Good info especially since I own a 2017 3.5 eco boost Ford.
    Milage is 43000 no issues yet.
    Need to know where I stand.

  2. I have a 2019 raptor never been abused or road hard.
    82,000 miles 3 valves have holes in them this was discovered after replacing the cam and all the parts mentioned
    It started but not correct.
    So the techbpulled the plugs then scoped to find the valves.

    I am number 7 person with this issue.
    In the state of Illinois.

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