Maintenance Tips, Tricks And Hacks For Your Vehicle

6 Symptoms Of Bad Rollover Valve




The rollover valve has a job to prevent any liquid from getting out of the fuel tank in an event of an accident (as the name suggests: if the car rolls over). However, the rollover valve also allows the fuel tank to breathe and release pressure or vacuum during day-to-day operation. Although built to last as long as the vehicle does, these valves tend to prematurely fail.

The most common symptoms of a bad rollover valve include a check engine light (usually a P0455 trouble code), engine stalling, unable to start the vehicle, failed emissions test, exhaust smell inside the car, or clunking noise when accelerating and stopping.

Key Takeaway

  • Check engine light can be triggered if the rollover valve is bad.
  • Engine stalling due to restricted fuel flow.
  • No starting from insufficient fuel flow.
  • Failed emissions test.
  • Exhaust smell inside the car.
  • Clunking noise when accelerating or stopping.

6 Symptoms Of Bad Rollover Valve

6 Symptoms Of Bad Rollover Valve

If you suspect that your rollover valve is bad, check for these six most common symptoms that will help you to pinpoint the problem.

1. Check engine light

6 Symptoms Of Bad Rollover Valve

If your car’s check engine light is triggered, it could be a sign that something is wrong with your rollover valve. The rollover valve is responsible for regulating and controlling the emission of fuel vapors from the vehicle and into the atmosphere. Generally, when this part fails to function properly, an abnormality can cause your check engine light to become illuminated.

While a rollover valve might seem like a minor part, it is essential for proper vehicle operation. This pipe-shaped rubber valve is located in the fuel tank and controls the airflow from the tank. It’s designed to close when the car rolls over so that fuel does not escape. But, if it becomes damaged due to age or wear, it could get stuck in the open position. This change in air pressure would trigger a check engine light since abnormal air pressure can affect engine performance and throw off other sensors.

Over time, oil or sludge buildup can further clog or damage the rollover valve. This will result in reduced engine power or misfires which are also indicated by warning lights on the dash. To help ensure your vehicle runs smoothly, regularly inspect your rollover valve to look for signs of damage. Replace worn-out components immediately to prevent triggering that pesky check engine light. In this way, you can ensure that all safety precautions are taken and avoid any costly repairs down the line.

2. Engine stalling

One telltale sign of a bad rollover valve in a car is the engine stalling. The purpose of the rollover valve is to help keep fuel from gushing into the carburetor during emergencies such as a rollover accident or hard cornering. But if it fails, fuel can accumulate in the engine, causing it to stall and potentially leading to an accident.

A rollover valve is an important part of a vehicle’s engine, impacting its ability to run efficiently. When a rollover valve is not present or working properly, it can cause the engine to stall. The rollover valve controls fresh air coming into the fuel delivery system. This air helps reduce the risk of fire when gasoline enters the cylinder after ignition has occurred during a sharp turn or sudden stop. If there is no rollover valve, then an explosive mixture of gasoline and air could enter the engine, potentially leading to serious damage.

When a rollover valve isn’t functioning properly, it can cause stalling due to an inadequate supply of fuel entering the combustion chamber. Without enough fuel, there will be no combustion and thus no power generated for your engine now causing your vehicle to stall.

It’s important to have your rollover valve checked regularly or replaced if necessary.

A faulty rollover valve not only affects your vehicle’s performance but also puts your safety at risk. Left unchecked, the problem could lead to more serious issues like sudden unintended acceleration or even a complete breakdown of the vehicle.

3. No start

6 Symptoms Of Bad Rollover Valve

A car’s rollover valve is an essential part of the vehicle. It controls fuel vapor by blocking it from passing from the evaporation control system to the intake manifold. If that vapor is allowed to enter the engine, it can alter combustion and create performance issues. Unfortunately, there are a number of signs that indicate a bad rollover valve. They often manifest in frustrating instances of a vehicle struggling or being unable to start.

A rollover valve is part of the fuel system and needs to hold enough pressure for fuel to flow freely from the tank to the engine. If it fails, then not enough pressure will be built up and fuel won’t reach where it needs to go. As a result, you will get no response when turning the key – literally no spark in the chamber – because there’s nothing to burn.

However, it’s vital to determine whether a faulty rollover valve may be at fault as soon as possible as ignoring it can lead to a buildup of gas and create hazardous conditions like possible fire and explosion risks until repairs are made. Therefore, if your car struggles or fails to start, have it diagnosed promptly by qualified professionals. They can pinpoint and rectify the underlying issue at hand.

4. Failed emissions test

6 Symptoms Of Bad Rollover Valve

When a car begins to fail its emissions tests, it can be difficult to determine the source of the problem. One common cause is a faulty rollover valve. This valve is responsible for reducing hydrocarbon and carbon monoxide levels in the exhaust system. If it becomes blocked or damaged, these levels can rise significantly.

The most obvious symptom of this issue is an overall decrease in engine performance. Ignition may become sluggish, power and acceleration reduced, and fuel economy will suffer. Over time, this can lead to an unhealthy buildup of unburnt fuel in the system, eventually leading to higher concentrations of noxious gases being released into the air.

This will not only place unfair demands on the engine but also be detected during a tailpipe test. There will be a problem when attempting to pass emissions guidelines. Therefore, it is important for car owners to have their vehicles regularly inspected for bad rollover valves. It may save them from painful penalties down the road.

5. Exhaust smell inside the car

Cars are complex machines with many parts that work together in harmony to ensure a smooth driving experience. One of these parts is the rollover valve. It is designed to provide an airtight seal and keep exhaust fumes out of the vehicle cabin.

Unfortunately, if the rollover valve fails or becomes clogged, it can start to leak exhaust gas into the cabin. This will result in a tell-tale nasty smell inside the car. In addition to this unpleasant odor, other symptoms may begin to occur. For instance, a failing rollover valve might make noise when accelerating or reduce engine power due to a lack of backpressure from the exhaust system.

In either case, replacing or servicing the rollover valve should be done as soon as possible. Not only will this fix the acrid smell in your car, but also restore performance and fuel efficiency. And while it can be easy to assume the worst when hit with an exhaust odor, in most cases it’s simply caused by something as simple as a bad rollover valve.

6. Clunking noise when accelerating or stopping

6 Symptoms Of Bad Rollover Valve

If your car is making a clunking noise when you accelerate or stop, it could be a sign of a bad rollover valve. The rollover valve prevents fuel and toxic fumes from escaping into the vehicle’s cabin when sudden movements. These sudden movements are associated with acceleration and braking.

Additionally, this valve helps to reduce emissions by allowing unburned fuel to vent back into the engine’s air intake system. When the rollover valve has gone bad, however, these protective functions are compromised and potentially hazardous fumes can enter the cabin.

Furthermore, if an internal component of the valve damages other parts of the exhaust system like mufflers or catalytic converters then it will create a loud clunking sound every time you start up or stop your vehicle. If you hear any such noises coming from your car, take it to a qualified mechanic immediately. They can diagnose and repair any issues with your car’s exhaust system.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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