To find them, you'll need to:
1. Identify your engine: Check your vehicle's documentation or the engine bay for an engine code (usually stamped on a metal plate). Knowing the engine type helps determine the specific vacuum routing.
2. Locate the vacuum source: This is typically the intake manifold. Look for a number of smaller hoses connected to it, often near the throttle body. These are your primary vacuum sources.
3. Follow the hoses: Trace each hose from the manifold to where it connects. Common destinations include:
* Brake booster: A large hose leading to a canister-like device near the firewall. This is usually a very thick hose.
* Distributor vacuum advance: A small hose to a fitting on the distributor.
* EGR valve (Exhaust Gas Recirculation): A hose connecting to a valve near the intake manifold.
* Various emissions control devices: Several smaller hoses connected to different components of the emissions system.
* HVAC system (heating and air conditioning): Hoses controlling the vacuum-actuated components of your climate control system.
4. Consult a repair manual: A repair manual specific to your 1991 Dodge Shadow (with the correct engine) will have a diagram showing the vacuum hose routing. This is the most reliable way to identify each hose and its purpose. You can often find these online as PDFs or purchase a physical copy.
Caution: Vacuum hoses can be brittle and prone to cracking with age. While inspecting, check their condition and replace any that are cracked, damaged, or disconnected. Improper vacuum routing can affect engine performance, emissions, and even braking.
