How to Troubleshoot a Big Block Chevyby Bobby R. Goldsmith
The big block Chevy engine is the powerplant at the heart of numerous vehicles, from hot rods and classic cars to daily driving passenger sedans and heavy duty trucks. The big block Chevy is a rugged engine, but there are numerous problems that often creep up during its life. Troubleshooting the big block Chevy engine is fairly straightforward, as the simplicity of the design reduces the number of possible sources of malfunction. Generally, the most common problems for a big block Chevy are cooling problems, valve train problems, aspiration problems or timing problems.
Check all fluids in the engine. This includes oil, coolant, power steering, brake and automatic transmission fluid. Check the amount of coolant in the overflow bottle. Excessive storage of coolant in the overflow may be a symptom of a bad thermostat, or a water pump that is about to fail.
Check the engine's timing with the timing light. Attach the timing light lead to the batter, the probe to the spark plug wire for the number one cylinder, and point the light at the bracket near the harmonic balancer. The engine timing should be set between 10 and 13 degrees before top dead center, though this figure will vary by displacement size, engine modifications and vehicle type.
Gap each spark plug with the gapping tool. Use the .030 gap for all eight spark plugs.
Check all radiator hoses for excessive wear or fracturing. Check fan and accessory belts for wear as well. Replace if necessary.
Examine the fuse block and all wiring in the engine compartment for any obvious malfunction. Pay special attention to wires and leads that are rubbing against any metal or plastic surface. Friction will wear down the coating on wires and could lead to an eventual short.
- Keep an eye on your fuel economy. Sudden decreases in gas mileage are often the first indicator that something in the Chevy big block is not functioning properly.
Things You'll Need
- Timing light
- Standard socket set w/ratchet
- Torque wrench
- Spark plug gapping tool
- Phillips head and flathead screwdrivers
- Always disconnect the battery when replacing wiring or electrical components.
Bobby R. Goldsmith is a writer and editor with over 12 years of experience in journalism, marketing and academics. His work has been published by the Santa Fe Writers Project, "DASH Literary Journal," the "Inland Valley Daily Bulletin" and WiseGEEK.