A GMC Canyon owner took their truck to a dealership after it stopped starting and displayed several diagnostic trouble codes. What initially appeared to be an electrical problem turned into a recommendation to replace the entire engine.
After five hours of diagnostics, the dealership quoted about $25,000 for an engine replacement. The owner said that was roughly what they originally paid for the 2016 GMC Canyon.
The owner shared the experience in an October Reddit post on r/MechanicAdvice, asking whether the replacement was necessary and how to obtain another evaluation.
Although commenters agreed the dealership’s findings suggested serious mechanical damage, several questioned the replacement price and encouraged the owner to explore independent repair options.
Engine Damage Discovered
Quoted for an engine replacement and looking for second opinion – How to go about this?
by
u/BFerda in
MechanicAdvice
The Canyon’s 3.6-liter engine had generated several trouble codes involving sensors, including the camshaft position sensors. The owner initially suspected an electrical short and attempted troubleshooting before visiting the dealership.
Technicians inspected the timing chain and found it intact. However, subsequent compression testing revealed 30 pounds per square inch (psi) in cylinder one, 100 psi in cylinder three, and zero psi in cylinder five.
A leakdown test also reportedly showed 95% leakage in cylinders one and five, with air escaping through the exhaust valves.
During a borescope inspection, technicians observed what they described as possible piston-to-valve contact and metal debris. The findings suggested the engine’s timing may have jumped, potentially causing internal damage.
Dealership Trust Issues
The owner explained that previous experiences had already damaged their confidence in the dealership.
Those disputes reportedly involved repairs performed without proper approval and unresolved purchase incentives that the owner said had cost thousands of dollars.
The owner also faced another complication: an upcoming move to a city approximately eight hours away. That made arranging multiple inspections more difficult.
Despite the truck’s age and mileage, the owner preferred repairing it rather than purchasing another vehicle.
Mechanics Weigh In
Reddit responses focused on the dealership’s diagnostic findings and the cost of replacing the engine. Several commenters considered the compression and leakdown results consistent with significant internal damage. Others suggested replacing the engine could be more practical than rebuilding the existing one.
However, the quoted price attracted skepticism. One commenter noted that a replacement engine costs about $5,000 and includes a five-year, 50,000-mile parts warranty. That figure excluded installation labor, and the warranty would not cover labor costs for another replacement.
Others recommended obtaining estimates from independent mechanics for used or remanufactured engines before authorizing dealership repairs.
Owner Considers Options
The owner outlined plans to request the dealership’s diagnostic documentation, arrange a tow to another repair facility, and contact engine specialists for additional estimates.
The discussion did not establish whether another mechanic had inspected the Canyon or independently confirmed the suspected internal damage.
In a follow-up response, the owner thanked commenters for their suggestions and expressed frustration that a visit prompted by apparent electrical trouble had resulted in such an expensive engine diagnosis.