Tips for Exhaust Butterfly Valve Servicing

Exhaust butterfly valves are s noise reducing type of actuator commonly used in motor vehicle exhausts. In this article, PIF explains how this type of valve functions and provides servicing tips to fix common exhaust butterfly valve issues.

What are exhaust butterfly valves?

Exhaust butterfly valves are a type of actuator used to silence or reduce noise emitted from certain applications. These valves are commonly associated within the automotive industry, as they will often be found working within cars or motorbikes.

When exhaust butterfly valves work efficiently, engines run quieter at low RPM and start much quicker and smoother. In addition, the heat from the exhaust manifolds will warm the fuel-air mixture for a cleaner start.

However, there are several situations which can cause exhaust butterfly valves to malfunction. Let’s take a closer look at some of the common errors that might lead to failures and how best to address them during servicing.

Servicing tips for exhaust butterfly valves

Sticky butterfly valves

If exhaust butterfly valves remain closed, superheated gases may become trapped within the exhaust manifold. This adversely affects vehicle performance because the trapped gases prevent fuel from entering the engine. This can be fixed during oil changes by rotating the counterweight that controls the motion of the valve. If the valve shaft is jammed, gently tap repeatedly with a hammer to loosen it.

Closing butterfly valves

By comparison, should exhaust butterfly valves remain stuck open, engines will start to slow as the gas-air mixture will be too rich. Unless valves are calibrated to accommodate a balanced fuel mixture, unburned gasoline will slosh around inside the cylinders, causing other vehicle components to foul.

To close the valve, apply a solution of alcohol mixed with powdered graphite to serve as a lubricant for the shaft. Should this not take, spray with a solvent that removes rust, as this will penetrate areas that the makeshift lubricant can’t reach.

Lubricating butterfly valves

Finally, as a general rule of thumb for servicing exhaust butterfly valves, do not lubricate with any kind of oil. If a lubricant is required, stick to the solution above as even the thinnest oil types will make the valve seize and seal tighter than before, in either open or closed positions.

If you would like to learn more about exhaust butterfly valves, click here to view.