* Intake Manifold: This is a major source of vacuum. You'll likely find several lines connected here, often to a manifold vacuum port or multiple smaller ports.
* Brake Booster: A large vacuum line will run from the intake manifold to the brake booster. This is usually one of the thickest vacuum lines.
* Transmission (if applicable): Some transmissions use vacuum for shifting, requiring a line connected to the intake manifold or a dedicated vacuum source.
* Distributor (older engines): Older 5.3L engines (pre-electronic control) might have a vacuum line connected to the distributor for advance control. Modern engines use electronic control.
* HVAC System: Vacuum can control components of the HVAC system, like the blend door actuators. Lines for these are typically smaller diameter.
* EGR Valve (Exhaust Gas Recirculation): This valve regulates exhaust gas recirculation and often has a vacuum line connected to control its operation.
* PCV Valve (Positive Crankcase Ventilation): The PCV valve is usually connected to the intake manifold to help ventilate crankcase gases.
To find the lines on *your* specific engine:
1. Consult a repair manual: A repair manual specific to your year and engine code is the best resource. It will have diagrams showing the vacuum line routing.
2. Use a diagram: Online resources like repair manual websites (often subscription-based) or parts websites (like AutoZone, Advance Auto Parts) may have diagrams for your specific engine. Search using your engine's VIN or year/make/model/engine code.
3. Visual inspection: Carefully examine the engine bay. Look for rubber lines connected to various components. Trace them back to their source to understand their function. Be cautious of hot components.
Warning: Improperly connecting or routing vacuum lines can cause serious problems, from poor engine performance to brake failure. If you're unsure about anything, it's best to consult a professional mechanic.
