1990 Ford Bronco 4.9L Thermactor Air Pump, Bypass & Check Valve Diagram

This document is a factory-style line-art schematic of the secondary air injection (Thermactor) system components on an inline six-cylinder Ford engine, consistent with the uploader's claim of a 1990 Ford Bronco 4.9L with automatic transmission. The drawing shows the engine from the side with an arrow indicating 'FRONT OF ENGINE.' Three key emissions components are highlighted in red: the belt-driven AIR PUMP mounted low at the front of the engine, the AIR BYPASS VALVE mounted higher on the engine near the accessory bracket, and an inline CHECK VALVE located in a hose at the left (rear) of the illustration. Shaded/gray hoses illustrate the air routing: from the air pump up to the air bypass valve, then along a hard tube/manifold running the length of the cylinder head, and to the check valve hose. The figure reference number A13527-A appears at the bottom right. A reader can learn where each secondary air component is physically located on this engine and how the air hoses are routed between the pump, bypass valve, and check valve, which is useful for identifying, testing, or replacing Thermactor system parts.