If you own a 2020-2025 Chevrolet Silverado 1500 or GMC Sierra 1500 with a 3.0L Duramax LM2 or LZ0, you might have noticed an annoying squeak or clunk coming from the left rear leaf spring. Turns out, there’s a reason for it-and GM has a solution.

This issue is caused by diesel fuel contamination. When you fill up your truck, excess fuel can run down the filler neck or splash back, soaking the left leaf spring. Over time, that fuel can degrade the rubber bushing in the spring, leading to the noise.

Does your truck have this issue? Tell us about it in the official forum discussion thread here

How to Fix It: GM’s Official Solution

GM has issued Technical Service Bulletin (TSB) PIT6177B to address this issue. If your truck is still under warranty, you should take it to the dealer and have them fix it at no charge. Here’s what they’ll do:

  1. Inspect the front half of the left leaf spring for signs of diesel fuel contamination.
  2. If the rubber bushing is soaked with fuel, the leaf spring will need to be replaced.
  3. To prevent future contamination, a polyethylene foam seal will be installed around the fuel filler pipe.
  4. The dealer will clean off any residual diesel fuel from the filler neck and leaf spring.

This fix is covered under the truck’s Bumper-to-Bumper warranty in Canada and under similar coverage in the U.S. Check your warranty status with your dealer before heading in.

Close-up of the 3.0L Duramax diesel engine under the hood of a GMC Sierra or Chevrolet Silverado.
The 3.0L Duramax diesel in 2020-2025 Silverado and Sierra 1500 trucks is a powerhouse, but some owners have reported a rear leaf spring squeak due to fuel contamination. Learn how to fix it with GM’s TSB or a DIY solution.

What If You’re Out of Warranty?

If your truck is no longer covered under warranty, you can DIY this fix to avoid costly repairs down the road. Here’s what you need:

  • Polyethylene Foam Pad (8mm thick, 4″ x 4″) – Available online (GM suggests an option from Amazon: B0C7R8F7BX)
  • A way to cut the foam to the right size (a large socket or bearing race driver can help).
  • Basic tools to remove the fuel filler pipe housing.

DIY Steps:

  1. Remove the fuel filler pipe housing.
  2. Clean off any diesel fuel residue from the pipe and surrounding areas.
  3. Cut the polyethylene foam pad to match GM’s specs:
    • Inside diameter: 3.0 inches
    • Outside diameter: 3.75 inches
    • Thickness: 0.4 inches
  4. Install the foam seal around the fuel filler pipe.
  5. Reinstall the fuel filler pipe housing.

If your leaf spring bushing is already soaked, you may need to replace the entire leaf spring, which is a bigger job but still doable if you have the tools.

Do you have this issue? Let us know!

If you’ve been hearing a squeak or clunk from the rear of your Duramax Silverado or Sierra, this TSB could be the reason. If you’re still under warranty, take it to the dealer before it becomes a bigger issue. If you’re out of warranty, installing the foam seal yourself can help prevent future problems—and save you money.

Got a squeaky leaf spring? Let us know in the forum if this fix worked for you!