The Volvo Parts, Accessories &
Performance Specialists Since 1963

Volvo PCV Issues Explained

2020-01-14 - Megan Russell

Having PCV issues? You are not alone. 

Over the years we have heard every complaint about the Volvo PCV system in the book. So we have created upgraded kits, Volvo OE PCV kits and economy kits to help everyone with their PCV replacement. Regardless of product quality, the issues are still persistent.

So what is making these PCV systems fail?

Lets chat about that. 

Properly servicing the flame trap / crank case ventilation system generally means replacing all the system components and can be fairly costly as labor as the intake manifold must be removed. Generally speaking the flame trap system components need to be replaced about every 100K or so depending on the quality of oil used, oil change intervals and driving conditions. The plastic tubing and fittings get extremely brittle with age and also becomes restricted internally due to oil deposits and sludge forming inside the tubing. The restricted breather flow results in excessive crank case pressure, which in turn begins to force oil past seals. If left unchecked, seal failure can occur which in extreme cases could result in rapid loss of oil pressure and catastrophic engine failure.

PCV issues:

Positive crankcase ventilation or PCV.

What it is: PCV Valve, Volvo’s do not have the more common "PCV Valve" but rather a series of hoses and a PCV box. These pieces combined, do what PCV valve used to do on cars, more commonly in the 60's and 70's.

The first positive ventilation was called a road draft tube. A road draft tube simply was a tube that came off the side of the engine and faced under the car. This tube, using the vacuum created in the car, would extract gasses from the engine and simply dump them on the ground, along with some oil.  This is why when we were young; we would see that black strip down the highway, it was the gasses and the oil coming out of the PCV system.

Beginning in the 60's engineers began to use the vacuum in the intake system to draw the gasses out of the crankcase. This would create positive crankcase ventilation and re-burn these gasses, so there was less pollution. There were studiesdone at the time that showed 50% of the hydro-carbons in the air were from crankcase ventilation.

Volvo since the 60's doesn't actually use the PCV valve, but rather a oil separator box and a series of rubber hoses, that connect your intake system to your crankcase. The breather box separates the oil mist from the vapors, so you don't end up re-burning all that oil.

The PCV system suffers greatly from degradation by many factors like environment, the heat and the chemicals under the hood, and they fail frequently. This has become one of the most common maintenance issues in a modern Volvo. You are not alone.

Volvos that are driven shorter distances, that don't get as warm, do not heat cycle the oil as thoroughly. They'll develop more containments in the system, and this will ultimately fail the PCV components more frequently.

In short, there really is no mileage interval for PCV maintenance.

If you make shorter trips, you might do it more than if you take longer trips in the same vehicle. Some people can go hundreds of thousands of miles without any maintenance on their PCV system because that system is utilizing it's PCV system better with longer trips than short.

As long as your system is intact, no cracks in the hoses, nothing is plugged up, it will function just fine. But if not of your hoses break, the nylon parts, rubbers parts or box crack, you will start seeing more PCV issues.

We've reached the point where oil leakage in these Volvo's is unacceptable. Oil leakage usually means that there is a crankcase pressure developing which is a sign that you are having issues with your PCV system. Also minor cracks and failures in the PCV system hoses can cause check engine lights as the ECU tries to calibrate around the small leaks in your intake system.

Due to the hostile environment that these PCV systems operate in, lower quality products have a higher failure rate. And it is always suggested that you go with OE or the IPD Heavy Duty PCV System Kits for your Volvo.

Most home mechanics can do this job in their driveway if you have basic hand tools.

Most PCV kits come with:

  • Oil separator box
  • All breather hoses
  • All breather hose clamps
  • Intake manifold gasket
  • Fuel injector seals
  • Oil dipstick tube seal

Though it should be everything you need to replace your PCV system, as mentioned before, there might be some smaller gaskets, orings or seals that need to be replaced along the way. It is more often than not, something you only notice after taking your entire PCV system apart. It is always adventageous to check over your entire system for parts that will most likely need to be replaced when doing your Volvo's PCV system. 

As noted in this PCV Kit review:

"First attempt at tackling this project. No major issues; however, if this is your first time, count on extended time installing. Helps if cooling fan is removed to provide extra working room-- Patience and cussing when necessary also helps. Product and fit were perfect. There are articles and videos online for how to replace, but an IPD how-to video would be great as well. My only complaint with the kit is it should come with the fuel injector pintle caps (washers). Mine were so brittle when replacing the o-rings they broke into several pieces. Took some extra time sourcing, but found some online."

These are items that need to be checked before doing your PCV system. These pintle caps are not included in PCV kits, as they are not commonly replaced at the same time. Always check your entire system before buying your PCV kit, you never know what might need to be changed in correlation to the PCV system. 


Common issues with Volvo PCV Systems:

There are a couple of things that get overlooked in the PCV system issue. The lifespan of PCV components varies widely based on operating conditions.

Usage: The PCV system likes to be used at higher RPM for long periods of times (like a trip on the freeway). It also likes higher temperatures to help vaporize the negative contamination in the oil and burn it through the PCV. But in the other direction, a car that is used in a cooler environment and shorter distances will load up and plug/fail the system rapidly. We have an employee who completely rebuilt their PCV system in their daily commuter about every 18 months, due to the cool/damp environment and a 7 mile commute on surface streets.

Wear: The contaminants in the oil are volatized and burned up by the PCV system. But, the amount of blow-by in an engine (the primary source of contaminants) changes dramatically as the engine goes through its life cycle. So, the amount of contamination the PCV system is required to handle in a 300k engine is dramatically different from the contaminants in a 100k engine.

Final: Kind of a combination of both of the above topics. The majority of contamination and plugging in your system happens during warm-up. This is why cars that are used for short distances need so much more PCV work. So you can’t really measure life cycle of PCV components in miles, but they are really measured in key cycles (temperature cycles).