Loud Metal tapping sound at startup of 3.8L

[SixFootSix]

My recent CARMAX purchase is back in the shop for repairs. They replaced the high mounted brake light and are trying to determine the cause of the loud tapping of the engine during the first minute of operation,after sitting for several hours.

The Hyundai mechanic has acknowledged the sound as not normal and is waiting on the service manager to hear it as well. It sounds like one of the valves is making the noise, or a possible emissions component chattering like a metal plate against a metal seal.

One thing I do know is that the noise is coming from the driver side front 1/3 of the engine head.

2016 Hyundai 3.8L Ultimate
51k miles

 

[NC356]

Wishing you good luck...........please be sure to post if you get a good result.
My same car, with 23k miles, developed a metallic knock that lasts about 30 seconds, after sitting for a few hours.
Under warranty, dealer replaced timing chain and cam timing sprockets, twice!
With no success. Now they won't discuss it any further.
But it's at 100k miles now; same noise, but no ill affects AFAIK.
I fear when I sell it it will come back as soon as new owner cold starts it. A quandary. Shame on Hyundai.

 

[SixFootSix]

Wishing you good luck...........please be sure to post if you get a good result.
My same car, with 23k miles, developed a metallic knock that lasts about 30 seconds, after sitting for a few hours.
Under warranty, dealer replaced timing chain and cam timing sprockets, twice!
With no success. Now they won't discuss it any further.
But it's at 100k miles now; same noise, but no ill affects AFAIK.
I fear when I sell it it will come back as soon as new owner cold starts it. A quandary. Shame on Hyundai.

The Service Manager claimed that the sound was only 10-15 seconds and within spec for the engine. I played three separate cold starts that had the tap sound for 45+ seconds each time.

He did offer to pay for both an oil analysis and also the Hyundai Dealer to diagnose the cold start sound. He assured me that any work would be covered by CARMAX.

I plan to get the oil analysis and dealer checkup next week, if service appointment can be scheduled.