Automotive borescope inspection is most useful when it answers a specific quality question and helps determine what happens next. A recent General Motors service procedure offers a practical example.
In an October 2026 update, GM outlined an inspection for certain 2026 Chevrolet Silverado HD and GMC Sierra HD vehicles with a possible cylinder-head oil-passage drilling issue. Technicians use a borescope to examine two machined surfaces and count the visible drill marks. The result determines the next step in the procedure.
A borescope finding sets the next step when the procedure ties a specific visual result to a defined action. In GM’s cylinder-head procedure, the drill-mark count on each head determines what happens next.
Technicians inspect the machined surface at the front of the passenger-side cylinder head and at the rear of the driver-side head from underneath the vehicle. GM notes that a right-angle attachment can help with the view. Technicians record the drill-mark count for each head.
That count directs the next step:
These criteria apply to the vehicles covered by GM’s dealer service program. They do not establish GM’s in-process manufacturing practice or criteria for other engines. The useful example for quality teams is how a specific visual observation is connected to a defined follow-up.
Start with the decision, then build the inspection around it. Before choosing equipment, make the decision path clear. What exactly should the inspector examine? What visible result closes the check, what triggers follow-up, and what should happen if the view is inconclusive?
A procedure is easier to apply consistently when it identifies the inspection location, the visual criterion, and the action tied to each result. Where possible, reference the target to a fixed datum or access point so inspectors can return to the same area. Define how to handle borderline findings and when the inspection should be reviewed or continued with another method.
ASNT’s overview of visual testing notes that visual testing can help identify areas that require additional inspection using other methods such as ultrasonic or radiographic testing. In practice, the procedure should make clear which findings warrant that follow-up.
A useful inspection record should explain what was examined and why the team reached its decision, so someone who wasn’t present can understand the outcome. Set a consistent record format that includes the following:
Pair a close-up image with a context image showing where it came from. If the view is too ambiguous to apply the inspection criterion, record it as inconclusive and follow the procedure’s defined next step, such as repositioning the probe for another view or escalating the inspection. This helps different inspectors handle the same unclear result consistently, review findings across shifts, and compare results over time.
For any borescope inspection, the probe must fit the access opening, reach the target, and show it at an angle that meets the inspection criteria, with enough illumination and image quality to reveal the details the inspector must assess.
GM’s procedure shows why viewing direction matters: it notes that a right-angle attachment can help technicians see the specified machined surfaces. If the access route is obstructed, articulation can help position the camera.
Teams that inspect a range of components often need different probe diameters and viewing directions from one job to the next. SPI’s Recon Pro and Recon: Gen.2 offer interchangeable probes, allowing teams to configure the system for each component’s access path and inspection target.
Probe specifications can narrow the options, but testing on your components shows whether a probe fits the access opening, reaches the target, and provides a useful image under your inspection conditions. SPI specialists can help identify configurations for your application. Request a no-cost demo to evaluate a configuration on your inspection.
A borescope inspection is only as useful as the decision it supports. GM’s October 2026 service procedure for certain 2026 Silverado HD and Sierra HD vehicles shows how: technicians count drill marks on two cylinder-head surfaces, and the count sets the next step. For automotive QC and NDT teams, the practical takeaway is to define the inspection location, visual criterion, follow-up action, and record format before choosing a configuration. SPI’s no-cost demo lets teams test equipment directly on their own components.
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