Oil Catch Can Installation: How It Protects Your HHO System

Why Catch Cans Matter for HHO Systems

HHO systems deliver gas to the intake tract — ideally through clean air and into clean combustion chambers. The PCV system delivers oil vapor to the same intake tract, depositing an oily film on throttle plates, intake valves, MAF sensors, and ultimately combustion chambers. An oil catch can intercepts this vapor before it reaches the intake, keeping all components clean. On direct injection engines where fuel doesn't wash the intake valves, the catch can is especially important.

How Catch Cans Work

A catch can is installed inline with the PCV breather hose. Crankcase gases enter the can, where the vapor cools and oil droplets condense and drop into the reservoir. Clean gases (mostly blow-by from combustion) continue to the intake manifold. The condensed oil is drained periodically (typically 3,000–5,000 miles).

Installation Steps

1. Locate the PCV hose connecting the valve cover to the intake manifold
2. Cut the hose and install the catch can inline — inlet from valve cover, outlet to intake
3. Mount the catch can to the firewall or a bracket in the engine bay in an accessible location
4. If using a dual-port catch can, connect the second port to the crankcase breather on the other valve cover (V-engines)

Sizing

A 150–300ml can is sufficient for most passenger cars. High-performance engines with more blow-by (turbocharged, modified) benefit from larger 500ml cans. Inspect at every oil change — a can filling in less than 3,000 miles indicates excessive crankcase pressure from worn rings.