Cold-start rattle points to cam timer issue
Ford EcoBoost engine has a documented problem
Dear Car Talk: I’m driving a 2018 Ford F150 with a 3.5L EcoBoost engine. About six months ago, around 25,000 miles, it developed a coldstart rattle.
What’s causing that, and what might be the long-term effect? Is there something I can do to mitigate the problem — if it is a problem?
One Ford service technician told me the quick oil change chain I use might not be using Motorcraft oil filters with the check valve, causing oil to drain out of the engine while sitting, creating a rattle from nonlubricated parts.
But a little research suggests most filters do have check valves and mine does, as well. Any advice will be greatly appreciated. — Tim
A: Hey, what’s the big deal? I chatter when I’m cold, too, Tim.
It sounds like one or more of your variable cam timers is faulty. Your engine has a technology called “variable valve timing.” By varying the timing of the opening and closing of the valves, the computer can either increase power or maximize fuel economy, depending on how hard you’re accelerating. It’s a great feature. Lots of modern engines have it. And it’s actually extremely reliable. Except in your case, Tim.
The timing of the valves is controlled by four little devices called variable cam timers. If the engine oil level gets low, or if the oil is really dirty, those VCTs can get noisy.
“But wait,” you say. “My oil level is not low. Nor is my oil dirty.”
I believe you, Tim. You’ve only got 25,000 miles on this truck and you appear to change your oil regularly. So, my guess is that one or more of those VCTs is defective.
In fact, Ford had to issue a Technical Service Bulletin to its dealers to alert them to this problem on the 3.5L EcoBoost engine and advise service departments on how to fix it.
How do they fix it? They replace all four of your VCTs.
I’m assuming you’re still under warranty — or you have a repair order complaining about this problem to your dealer while you were under warranty.
That’s good, because it’s a 10-hour job, plus parts. But that’s what you need, Tim. Point your dealer to TSB 20-2315 if they continue to give you a tap dance about the valve in the oil filter. It’s the VCTs. Good luck.
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