Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Crankcase Vent Filter

Bad Symptoms of Vent Filter

Bad or Failing Crankcase Vent Filter Inspection

by a top-rated mechanic at your home or office

Virtually all vehicles on the road today are equipped with internal combustion engines that have some sort of crankcase ventilation system. Internal combustion engines inherently have at least a small amount of blow by, which occurs when some of the gases formed during combustion escape past the piston rings and down into the engine’s crankcase. The crankcase ventilation system works to relieve any pressure from the engine’s crankcase attributed to blow by gases by rerouting the gases back into the engine’s intake manifold to be consumed by the engine. This is necessary, as excessive crankcase pressures can cause oil leaks to form if allowed to build too high.

The gases are usually routed through a PCV valve and sometimes a crankcase ventilation filter or breather filter. The crankcase ventilation filter is one of the only components of the crankcase ventilation system, and is therefore an important piece in maintaining the functionality of the system. The crankcase vent filter works the same way as any other filter. When the crankcase ventilation filter needs servicing, it will usually display a few symptoms that can alert the driver that attention is required.

HAVE SYMPTOMS OF CAR TROUBLE?
Get an $80 diagnostic
by a top-rated mechanic at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

1. Oil leaks

Oil leaks are one of the symptoms most commonly associated with a bad crankcase vent filter. The crankcase filter simply filters the blow by gases to make sure that they are clean before they are rerouted back into the vehicle’s intake manifold. Over time, the filter can get dirty and restrict the air flow, and therefore pressure relieving capacity of the system. If the pressure builds too high, it can cause gaskets and seals to blow causing oil leaks.

2. High idle

Another symptom of a potential problem with the crankcase vent filter is an excessively high idle. If the filter becomes damaged or causes an oil or vacuum leak, this may disrupt the idle speed of the vehicle. Usually a high idle is a potential indication of one or more problems.

HAVE SYMPTOMS OF CAR TROUBLE?
Get your car fixed at your home or office.

Get a quote · Book an Appointment · Our expert mechanics come to you.

3. Decrease in engine performance

A decrease in engine performance is another symptom of a potential problem with the crankcase vent filter. If the filter becomes clogged and causes any vacuum leaks, this may cause a decrease in engine performance due to the disturbance in the air-fuel ratio. The vehicle may experience a decrease in power and acceleration, especially at low engine speeds. These symptoms can also be caused by a variety of other problems as well, so having the vehicle properly diagnosed is highly recommended.

The crankcase filter is one of the few components of the crankcase ventilation system, and is therefore important in maintaining full functionality of the system. For this reason, if you suspect that your crankcase vent filter may be having an issue, have the vehicle serviced by a professional technician, such as one from YourMechanic. They will be able to replace your failing crankcase vent filter and perform any services that may be required for the vehicle.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2422 OBD-II Trouble Code: Evaporative Emissions Control System (EVAP) Vent Valve Stuck Closed
Diagnostic Trouble Code (DTC): P2422 P2422 code definition Evaporative Emissions Control System (EVAP)...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...


Related questions

Q: Rough engine noise on startup, idle and low rpms

Hello. From what you describe it would appear that your low oil level may have something to do with the engine noise. First off, if the oil is low I would top it off as soon as possible, as low...

Q: Car cannot shift to reverse

It is possible this is caused by some dirt, grit, or other bit of trash in the valve body of the transmission. The valve body takes the mechanical selection of "Reverse" from the gear selector, and turns that into the...

Q: Excessive oil burning - 1986 Buick Electra Station Wagon

Hello. If the PCV system is not hooked up correctly, this will cause excessive oil burning. This needs to be checked and repaired first. If the PCV system is working then the issue is more than likely the piston rings...