2025 Suburban 5.3L - Lifter or Bottom End Failure? 11k Miles of Dealership Gaslighting - Seeking Advice

[George Yorkshire]

Hi Everyone,

I’m a professional driver in Virginia, and I’ve been getting the runaround from Chevy dealerships for the last 11,000 miles. My 2025 Suburban (5.3L L84) has a serious mechanical issue, and I’m being treated like I don’t know my own vehicle. I need your advice on how to handle this and how to escalate with GM.

The "Gaslighting" Timeline:

44,000 Miles: A metallic "knock knock" sound started while in Drive or Reverse with the brake applied (especially after long 8-10 hour shifts). Took it to the dealer; they said "Everything is normal."

45,000 Miles: "Low Engine Oil" light came on. Dealer told me it's a large vehicle and "oil consumption is normal."

49,000 Miles: Went back for the noise. They told me, "If the noise is from the transmission, we don't have a transmission specialist here, go to another dealer."

Same Day (Second Dealer): The noise disappeared by the time I arrived. They kept it for 2 days and said they couldn't find anything.

55,000 Miles: After 3-4 more visits, the noise finally happened in front of the Service Manager. He admitted: "Yes, this noise is NOT normal." However, the tech—who previously called it normal—now says it might be the Transmission/Torque Converter.

The Diagnostic (or lack thereof): After 2 days, they gave it back saying "No issues found." I insisted on a GDS2 scan for Misfire Analysis; they showed me 0 counts and said everything is fine.

The "Oil Filter" Incident: I requested the oil filter and a sample. They literally cut the filter open with a hacksaw—getting metal shavings everywhere—and handed it to me without even inspecting it for internal debris.

The "Bottom End" Admission: I took the car to my previous dealer again. After another 3 days of "nothing found," one tech finally admitted the noise might be coming from the Bottom End (Main Bearings). Their solution? "Drive it for another 4,000 miles, then we’ll check again."

Current Situation:

I have an engine making a clear mechanical knock, dealerships that contradict each other, and a business where I’m losing $500/day while they play games. Independent shops are split between "Lifter failure" and "Torque Converter."

My Questions:

Has anyone seen a case where the dealer asks you to drive 4,000 more miles on a knocking engine just to "see what happens"? Is this a tactic to run out the warranty?

I’m sending a sample to Blackstone Labs. If I find metal, can GM still deny a Long Block replacement by claiming the hacksaw cut contaminated the sample?

Given the history since 44k miles, do I have a strong Lemon Law case in VA even if they haven't "failed" a repair yet because they refuse to attempt one?

I’m tired of being treated like I’m crazy. Any advice on how to get GM Corporate involved immediately would be a lifesaver.

 

 

 

[silveradosid]

i would say you have to open a case file with gm and send them the video, no doubt there is something not right

[diyer2]

Low engine oil light should never have happened,IMO.

[George Yorkshire]

I had a shocking experience at a Northern Virginia dealership with my brand new 2025 Suburban. For two months, their 'Multi-Point Inspection' reports showed everything in green (Perfect condition). However, I didn't trust the reports and insisted they manually check the transmission and both front/rear differential fluid levels right in front of me.

The result? The technician admitted that the transmission and differential fluids were significantly low! When I confronted the Service Manager about why the previous reports showed 'Perfect' levels, he dismissively said, 'Maybe we just copy-paste those reports.'

It is clear that they only scan for electronic error codes and ignore manual fluid checks because warranty work doesn't pay them well. Also, a friend with the same 2025 model is getting 'Low Engine Oil' red alerts, and the dealer is brushing it off as 'normal for a big truck.'

My advice to the community: Demand a manual dipstick/plug check for all fluids. Do not let them give you a computer-generated 'Green' list without proof. These L84 engines and 10-speed transmissions are too expensive to risk due to lazy service departments.

[diyer2]

Dealers are not trustworthy.

[Snow White]

posted a reply to your other post but that's likely a spun rod or main bearing, if you're luck a wrist pin on a piston but that's definitely rotating mass.  for what it's worth, i had an old v6 s10 with a poorly reassembled rotating mass that knocked the same way for over 50,000 miles lol.  the bearing clearance was too much i believe on a main.

[GMCustomerService]

These knocking challenges you're having is not the GM experience we want for you to have with your 2025 Suburban, George. We recognize you're in need of support and we'd like the opportunity to help you to the best of our abilities. If interested, kindly send us an email with these details to [email protected] with your Username and Forum in the subject line along with this information.