When your engine is running, the combustion pressure pushes unburned fuel and gases from the combustion chamber to the crankcase. They pass through the piston rings, where they could leak, resulting in blow-by gases and harmful emissions.
The positive crankcase ventilation (PCV) system prevents issues by recirculating the vapors to the engine’s induction system, which has cylinders that burn them. The crankcase filter is one of the system’s crucial parts.
The PCV is connected to manifold vacuum and may have a valve with a spring and plunger or it may simply be a fixed orifice in the rocker arm cover such as you see on 4.0L Jeep Cherokee engines that have a replaceable rubber PCV orifice at the rear of the rocker arm cover. Some Chevy V8 pickups have a PCV orifice built into the rear of the left hand rocker arm cover.
The reason is that the intake stream provides the clean air needed, and since that air is being drawn through the MAF sensor, it is also factored into the fuel trim. If you remove the oil filler cap, PCV air will begin to enter there as an unmetered air feed, and the PCM will skew the fuel trim due to inaccurate mass airflow readings.
Older vehicles with round air cleaners typically had a crankcase filter that was part of the oil filler cap or they’d have a closure hose leading from the top of the oil filler cap to connect to the nipple on a plastic housing with a foam or fiber filter that was just inside the air cleaner housing. You can see it when you remove the top of the air cleaner.
Older vehicles with round air cleaners typically had a crankcase filter that was part of the oil filler cap or they’d have a closure hose leading from the top of the oil filler cap to connect to the nipple on a plastic housing with a foam or fiber filter that was just inside the air cleaner housing. You can see it when you remove the top of the air cleaner.
–Richard McCuistian, ASE Certified Master Automobile Technician
If the PCV side of the system becomes clogged or loses its vacuum, the crankcase vapors naturally reverse course and are funneled into the air cleaner.
What Does the Crankcase Filter Do?
The crankcase filter cleans the blow-by gases or escaped gases to remove contaminants like dust and dirt that will inevitably be drawn to the filter by the crankcase ventilation.
Where Is the Crankcase Filter Located?
The crankcase filter is usually on the breather hose on top of the crankcase. It could also be on the valve cover, depending on the vehicle. See opening text.
Symptoms of a Clogged Crankcase Filter
Dirt, debris, and other deposits can clog the crankcase filter over time. Here are the telltale signs that your vehicle’s filter is clogged:
Oil Leaks or There’s Oil in the Air Cleaner
Oil in the air cleaner is a telltale sign that the PCV side of the system is clogged and the blowby is coming back through the filter and into the air cleaner.
A blocked or clogged filter builds pressure, which leads to blown seals or gaskets that cause oil leaks. Of course, for that to be the case, both the PCV valve and the crankcase filter must be totally clogged. If one is clogged but not the other, it won’t blow seals.
Illuminated Check Engine Light
If the powertrain control module (PCM) detects any problem in the crankcase filter, it will illuminate the check engine light. Mechanics use a scanner tool to get the on-board diagnostics (OBD) code that indicates the issue from the system.
For example, if the tool logged a P1507 code, which means “Crankcase Filter Restriction,” it indicates that there’s something wrong with the filter.
Remember that other faulty parts can exhibit the same symptoms as a clogged crankcase filter. So be sure to cross-check the other signs or let a mechanic check your vehicle for a proper diagnosis.
Causes of a Clogged Crankcase Filter
If your crankcase filter is clogged, it might be due to the following:
Engine Oil
Engine oil can become thick and sludgy when it’s old or contaminated, which clogs the crankcase filter.
Dirt and Debris
The crankcase filter traps debris to prevent it from contaminating the oil. The dirt builds up over time, eventually clogging the filter.
Carbon Deposits
Carbon deposits are a result of incomplete fuel combustion. They create a wall of black soot that hardens and blocks the passageway.
Condensation
Moisture can build up in the crankcase filter, especially if the engine often runs at low temperatures. It tends to mix with other contaminants, which clogs the filter.
Why Is It Important to Clean the Crankcase Filter?
Keeping the crankcase filter clean helps maintain high engine performance. For example, if it’s clogged, it could cause oil contamination, resulting in sludging, engine wear, and power loss.
Does a Clogged Crankcase Filter Cause Rough Idling?
This might be caused by a disconnected PCV valve vacuum hose, but the crankcase filter can’t cause rough idle.
Can You Clean the Crankcase Filter Yourself?
Yes, you can clean the crankcase filter on your own, provided that you’re familiar with your vehicle’s PCV system and have the tools and know-how needed for the task.
When Should I Change the Crankcase Filter?
Experts recommend changing the crankcase filter when it’s damaged or at least once every two years.
How Long Does a Crankcase Filter Last?
It’s best to replace the filter every 25,000 miles or every two years, depending on which comes first. The lifespan of a crankcase filter depends on the filter type and the conditions of the engine.
Some factors might accelerate the need for replacement, such as weather conditions and the frequency of oil changes. It’s also worth noting that some manufacturers have recommended filter replacement intervals.
Final Thoughts
If you spot the symptoms of a clogged crankcase filter, address them immediately to prolong and preserve your vehicle’s performance and prevent irreversible damage. Take your ride to an auto repair shop as soon as possible.
How to Get a Quality Replacement Crankcase Filter Element
If it’s time to replace your crankcase filter, it’s best to do so as soon as possible. A clogged crankcase filter can lead to broken seals and gaskets in your PCV system as the pressure builds up behind it. Thankfully, CarParts.com is here if you need a new filter.
CarParts.com offers you the convenience of ordering from home coupled with a number of policies and guarantees made to let you order with confidence. Our price match and lifetime replacement guarantees are in place to ensure you’re always getting the best deals online for the parts you need. Meanwhile, our 60-day return policy lets you ship back any parts you aren’t satisfied with. We even offer fast shipping. As long as you’re in the continental US, we’ll have your new crankcase filter element delivered in as fast as two working days.
Place your order for a new crankcase filter element and other crankcase parts here at CarParts.com.
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