r/Justrolledintotheshop • u/EricShelby11 • 15h ago
You can't fix stupid, but you can charge for it.
Brand-new 2026 Ram 2500 with the 6.4L HEMI. The story I was given was that the customer accidentally filled it with diesel, drove approximately 4 miles, and then realized his mistake. Personally, I’m calling BS on that timeline. By the time the truck reached my bay, it was completely dead. Replaced the battery, only to discover the starter was also toast. All 16 spark plugs were absolutely COOKED. Hindsight being 20/20, those should’ve been some pretty obvious red flags. After replacing the plugs, I was still picking up an intermittent misfire on cylinder 7, maybe one or two counts per 200 RPM. I ended up driving it another 15–20 miles, thinking I was still dealing with residual diesel contamination in the exhaust, O2 sensors, and catalytic converters, and that the system just needed to clear itself out. Boy, was I wrong. Further diagnosis revealed that the cylinder 7 piston was literally coming apart. Looking back, I got tunnel vision on the fuel contamination and didn't give the mechanical side enough consideration early on. Definitely one of those diagnoses I'll remember.
