Part One: Understanding and Replacing the Emissions Check Valve on 1981-1987 XJ6 and V12 XJS Jaguars
The emissions check valve (part number EBC10196) is a critical component of the air injection system found on 1981-1987 XJ6 Jaguars and all V12 XJS models. This system includes the familiar air injection pipes that screw into the top of your cylinder head and helps reduce emissions during cold starts.
What Does the Emissions Check Valve Do?
The check valve acts as a one-way gate, allowing the smog pump to push fresh air into the air injection pipes, which feed the exhaust system. This additional oxygen helps burn off unburned fuel in the exhaust gases, reducing emissions.
When the smog pump is not operating, the check valve prevents exhaust gases from flowing backward into the air injection system. This safeguard protects the smog pump and other components from damage caused by hot exhaust gases.
Why Does the Check Valve Fail?
Unfortunately, the emissions check valve is prone to rust and deterioration over time due to its exposure to high temperatures, moisture, and the harsh conditions of the engine bay. A failed check valve often:
- Rusts away and falls apart.
- Allows exhaust gases to flow backward into the air injection system, potentially damaging components.
If your valve has failed, you’ll notice a decline in system efficiency, and in some cases, it could cause drivability issues or even fail an emissions test.
Preparing for DIY Replacement
Replacing the emissions check valve is a manageable project for a DIY Jaguar owner. In Part Two, we’ll cover the tools you’ll need, step-by-step instructions to replace the valve and tips for maintaining the air injection system.
Stay tuned and get ready to keep your classic Jaguar running clean and strong!
