2016 Sorento 3.3. Upon start up and placing trans in drive or reverse there is a rattle noise, like a heat shield loose type noise. Noise completely disappears after driving a few miles.
Local dealer says it's coming from the high pressure fuel pump and is completely normal. I think they are full of BS. This noise is not the typical timing chain rattle for these engines. Anyone else experienced this noise. Vehicle has 55,000 miles on it.
This is a very common complaint for the 2016 Kia Sorento with the 3.3L V6 engine, and you've described the symptoms perfectly. That specific rattling noise that goes away after a few minutes of driving is a classic indicator of a problem with the **timing chain tensioner**.
Why It's Happening
The engine's timing chain system is a complex assembly that includes the chain itself, guides, and tensioners. The tensioners use a combination of a spring and oil pressure to keep the chain taut.
- When the engine is off for a while (a "cold soak"), the oil drains out of the tensioner.
- When you start the car, it takes a few moments for the oil pressure to build back up and fully pressurize the tensioner.
- During those first few moments, especially when the transmission is placed under load (in Drive or Reverse), the chain can have a bit of slack, causing it to rattle against the guides or the timing cover.
- As soon as the oil pressure builds and the tensioner pushes back out, the rattle disappears.
This is a known issue on these engines, and Kia even released a technical service bulletin (TSB) for some model years to address this specific problem. The TSB outlines a procedure to replace the timing chain tensioner with an updated design that has a finer pitch on the teeth to help solve this issue.
Is It a "Heat Shield"?
It's understandable why you'd think it's a heat shield. That loose, rattling sound is very similar. However, the fact that the noise only happens on startup and under load, and then completely disappears after the car is warmed up, strongly points away from a loose heat shield. A loose heat shield would typically rattle over bumps or at specific engine RPMs, but it wouldn't consistently stop after a few minutes of driving.
Your Next Steps
1. Check Your Oil: First and foremost, check your engine oil level. A low oil level can exacerbate this problem. Make sure it's at the correct level and that you're using the manufacturer-recommended oil viscosity.
2. Confirm the Diagnosis: The best way to confirm this is to take your vehicle to a qualified mechanic, preferably a Kia or Hyundai specialist. They can use a mechanic's stethoscope to listen to the timing cover area to pinpoint the noise. They are also aware of the technical service bulletins for this issue.
3. Consider the Repair: While a brief rattle may seem harmless, a failing timing chain tensioner can eventually lead to the timing chain skipping a tooth. If that happens, it can cause catastrophic engine damage (bent valves, etc.). It's a job that requires removing the timing cover, which is a big and expensive job. While they're in there, it's often a good idea to replace the chain and guides as well.
I would strongly recommend getting this looked at by a professional to prevent a more serious and costly repair down the line.
