[SOLVED] 2020 SEL AWD - Loud tapping noise, exhaust-side valve cover near #3 & #4 cylinders (different than previous tapping noise I reported)

[fletcher969]

Hi all,

 

As the title indicates, this is NOT the same loud tapping+rattle noise I previously posted about recently in another thread in this forum.  The tapping described in this post only became evident AFTER that noise was fixed.  Given how many people complain about EcoBoost tapping noises, and I've experienced two different varieties, I thought this solution might be worth sharing.  Here's the tapping noise to which I'm referring in this post:  https://drive.google.com/file/d/1QP4IAkaUk_68z3KxZwLQGhBsyfpaeFzx/view?usp=sharing

 

Anyway, at the time of purchase this engine was pretty quiet for an EcoBoost engine based on the several I've heard.  About 2 months ago the engine very quickly developed a loud tapping noise with some metallic rattling that ultimately was determined to be a failing HPFP (fuel pump) which was replaced by the dealer.  There's an audio of that in my other post if you're interested.  That fixed, the engine still had a loud tapping noise coming from the back driver's side of the engine, so I decided to see if I could pinpoint it with a stethoscope.

 

Long story not-so-long, everything was pretty quiet, including the intake side cover and the HPFP until I touched the steth to the exhaust-side valve cover at Cylinder #1 (i.e. passenger side) where I heard the tapping noise; however, the injectors are on that side, so I considered those as a potential source.  The noise got louder at Cylinder #2, but when I listened to the cover over #3 & #4 the sound was MUCH louder.  At some point I touched the steth to the high pressure fuel line, and it was the same sound, same frequency, just a whole lot louder in the steth despite being silent to the naked ear.  I thought about that for a couple of days, noticed something the umpteenth time I looked the engine over that I hadn't noticed before, and I formed a hypothesis:  The high pressure fuel line was resonating inside the valve cover.  I wondered what had changed, because again, the engine was quiet before the HPFP replacement.

So what had I noticed?  Turns out on this version of the 2.0L the HPFP was moved from the end of the exhaust side to the same end of the intake side, and in this configuration part of the high pressure fuel line passes over the exhaust-side valve cover where it is anchored to the top of the cover using a bracket and a bolt...over the #3 & #4 cylinders.  There's a second bracket on the intake side, but it wasn't noisy there, so I didn't bother.  I removed the exhaust side bolt (and noted it was really easy to loosen), and carefully and barely separated the bracket from the cover, had my GF start the engine, and the loud tapping noise was gone. 

 

I was correct - the fuel line was resonating inside the valve cover. 

 

My final assessment was that whenever the tech replaced the HPFP, he necessarily had to loosen and detach the fuel line brackets, but when he put everything back together, he forgot to torque the exhaust-side bracket bolt.  As it loosened it allowed the bracket and bolt to vibrate at the same frequency as the HPFP fuel line, and that was transferred to and resonated inside the valve cover.  Once I reinstalled the bolt and tightened everything down properly, no vibration, no noise.

 

So, if for whatever reason you hear a tapping noise resonating from your valve cover, follow the high pressure fuel line, and make sure the bolts used to secure same are torqued tight.  It could be a cheap and easy fix to an annoying, expensive-sounding problem.