The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

Loud Exhaust Rattle/Hissing on 2017 GMC Canyon V6

0

Ryan M. · rep 0 · May 22, 3:38 AM · 1 replies · solved · Question

Vehicle: 2017 GMC Canyon SLT

I've been hearing a really annoying rattling and hissing sound coming from underneath my 2017 GMC Canyon SLT, equipped with the 3.6L V6 engine. It's most noticeable when I first start the truck and during acceleration, especially under load. It almost sounds like an exhaust leak, but I can't pinpoint exactly where it's coming from.

The truck has about 85,000 miles on it. I haven't seen any Check Engine Lights, and performance seems mostly normal, though maybe a slight decrease in power. I'm worried it could be something serious like a cracked exhaust manifold or just a loose heat shield. Has anyone else experienced similar noises with their Canyon, and what was the culprit?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:38 AM

0

ClearTheCode admin answer:

A rattling and hissing sound from the exhaust system, particularly under acceleration, is a common complaint and can stem from several sources. Given your description, an exhaust leak is a strong possibility, but other components can also be at fault.

Common Causes:

  1. Exhaust Manifold Leak: This is a very common issue on many V6 engines, including the 3.6L. The manifold can warp or crack, or the gasket can fail, leading to a ticking or hissing sound that's often loudest when the engine is cold and under load. This can sometimes trigger a P0420/P0430 code over time if the O2 sensors are affected.
  2. Loose Heat Shield: Heat shields are designed to protect underbody components from exhaust heat. Over time, their mounting bolts can rust or loosen, causing them to rattle, especially at certain RPMs.
  3. Cracked Exhaust Pipe or Muffler: The exhaust system is exposed to harsh conditions, and pipes or welds can crack, leading to leaks and noise. The muffler or resonator can also fail internally, causing a rattling sound.
  4. Loose Hangers or Mounts: The entire exhaust system is held in place by rubber hangers and mounts. If these fail or become loose, the exhaust can bang against the undercarriage.

What to do:

  1. Visual Inspection: Carefully inspect the entire exhaust system from the engine down to the tailpipe. Look for black sooty spots (indicating a leak), cracks, loose components, or rust.
  2. Listen Carefully: With the engine running (and cold, if possible), try to pinpoint the source of the sound. A mechanic might use a stethoscope or a piece of hose to listen more precisely.
  3. Check Heat Shields: Gently tap on various heat shields to see if any are loose and producing a rattle.

When to see a shop:

If you can't identify the source of the noise yourself, or if you suspect an exhaust manifold leak or a cracked pipe, it's best to take your Canyon to a professional mechanic. Exhaust leaks can be more than just annoying; they can affect engine performance, fuel economy, and in severe cases, allow exhaust fumes into the cabin. A shop can safely lift the vehicle and perform a thorough inspection, potentially using a smoke machine to find leaks.

Menu

Help & account