Curing Common Valve Problems

Engine valves – even if you’re not a self-proclaimed gearhead, you’ve probably heard of this critical internal combustion component. Valves play a crucial role in making an engine run properly, but like any engine part, they can develop problems over time that, if not addressed, can eventually lead to costly repairs. 

First, a little background. Generally speaking, valves come in two varieties: intake and exhaust. Intake valves control the amount of fuel and air mixture that is allowed into the combustion chamber and exhaust valves are responsible for releasing spent gasses from the cylinders. 

The valves open and close at precise times, determined by camshaft lobes that move a rocker arm and valve spring assembly that pushes on the valve stems. The rocker assembly is actuated either through pushrods or direct contact with the cam lobes (referred to as an overhead camshaft, which is most common in modern engines).  

This seems simple enough, but the conditions in which valves operate are extreme. The sheer volume of strokes the average automotive valve has to make on a daily basis—thousands per minute—is hard to fathom.

So it’s no surprise then, that over time, valves can develop problems that can range from minor to catastrophic. Several different engine operational failures, such as a broken timing belt or overheating, can lead to valve damage (bent or broken valves). But even under normal operating conditions, common problems can surface.   

One of the more common issues is carbon buildup, especially in gasoline direct injection (GDI) engines where fuel is shot straight into the cylinders rather than passing through the intake valves. Carbon deposits on intake valves can restrict flow, cause valves to seat improperly, and create timing issues by adding weight. The buildup can lead to a loss of power, rough idle, hesitation, misfires, a drop in fuel economy and other problems.

Deposits on exhaust valves, though less common, can also cause improper seating, leading to burnt valve seats from hot exhaust gasses forcing their way through unsealed areas. A burnt exhaust valve can cause the same performance issues as above.

Valves can also stick for a number of reasons, such as deposits from oil or fuel, or weakened valve springs. A stuck valve will not only create performance problems—it could also cause a piston to make contact with the seat, causing major damage. Routine maintenance—regular oil changes and fresh fuel—can help prevent these valve problems.

Image shows GDI engine cutaway.
Notice that the fuel injector is placed inside the combustion chamber. Unlike traditional port injection where the fuel injector is placed before the intake valve, there’s no fuel to wash over and clean the intake valve.

Treating your engine with Sea Foam Spray through the intake and using Sea Foam Motor Treatment in your fuel and crankcase will also help to keep your valves carbon-free and operating as they should for many miles.