The crankcase breather system is often neglected and overseen although it has a major role in the proper functioning of your engine.
Because of this, various symptoms and problems may appear over time which can give drivers a big headache, especially with used cars.
In this article, the main focus is on these problems and symptoms caused by a faulty crankcase breather as well as some possible solutions.
What will be mentioned here comes from personal experience and may perhaps help if you encounter the same or similar problem (regardless of the car you drive).
Also, at the end of the article, you can find a video on this topic or watch it on our YouTube channel.
WHAT IS A CRANKCASE BREATHER?
In a nutshell, it’s an external part of the engine in charge of ventilating the crankcase.
If you don’t know, the crankcase is the part of the engine where, among others, engine oil is stored.
You see, while the engine is working, a certain amount of gases caused by combustion (better known as ˝blow-by˝gases) manage to pass the piston rings and enter the crankcase.
These gases then cause a pressure build-up in the crankcase, which if went unattended, can cause serious problems like gasket leaks, the engine burning oil, or even worse damage the engine.
To paint a picture, imagine an air compressor pumping air into a sealed container of engine oil all the time. Naturally, the pressure will build up inside the container. Over time, the container will simply have to start leaking or burst somewhere.
Apply this picture on to an engine and you should get a good idea of what the purpose of a crankcase breather is.
It wouldn’t hurt to take a look at this explanation provided from Wikipedia, where the whole system is explained in great detail.
SYMPTOMS OF A FAULTY CRANKCASE BREATHER
To be clear, in my case, these symptoms appeared over a certain period (almost a month).
Due to various circumstances (mostly the lack of spare time) I couldn’t tend to the problem right away.
Maybe better as I can explain what happened and in what order did the symptoms appear. This will maybe give you a head start if you encounter this problem and don’t let it get to the bitter end.
So, these are the symptoms in chronological order:
1. ROUGH IDLING
The engine worked flawlessly until I noticed that sometimes the idling became rough for no apparent reason. At first, it would happen when the engine warmed up to working temperature but as the problem got worse, it would idle roughly even when the engine was cold.
To clarify, the idling wasn’t that rough (like with a misfire or one cylinder not working). The whole time it was noticeable but barely.
Also, on two occasions I get high revving for a couple of seconds while the car was in a standstill.
2. OCCASIONAL LOW ENGINE PERFORMANCE
As the crankcase breather problem got worse, I noticed a decrease in engine performance.
Just like with the idling, this symptom was not that drastic. Also, it happened occasionally.
I would say roughly that the car lost about 10 percent of its normal power (this is my impression anyway).
The engine would bog down for a bit and come back to normal in a matter of seconds.
To be clear, the car was driveable the whole time.
3. OCCASIONAL CHECK ENGINE LIGHT
In the later phase of the problem, the occasional bogging down of the engine would soon be accompanied by the check engine light coming up in the dashboard.
After a couple of starts, it would go off.
So, when the engine started to bog down, the check engine light would soon come up.
4. SIMULTANEOUS LIGHTING UP OF THE EPC, TCS, AND CHECK ENGINE LIGHT
Now this symptom is perhaps exclusive to Skoda Fabia or perhaps other Volkswagen group cars of the same generation.
This symptom appeared at the final phase of the problem after the mentioned check engine light symptom.
Simultaneously the EPC (electronic power control), TCS (traction control system), and the check engine light came up on the dashboard.
Took me some time to conclude under what circumstances do these warning lights come up.
I concluded that it appears when I press the accelerator and gain speed while driving (like an overtake or turning at an intersection).
It looked something like this: the car starts to accelerate, the warning lights come up, the car bogs down a bit (barely noticeable), and the driving continues as normal.
Once the car is stopped and the engine turned off, the EPC and TCS go away but the check engine light stays on for a couple of days (roughly every five times the car is started the check engine light would go away).
The main point here is that the car was driveable the whole time without any major problems, despite all the warning lights were on.
5. OIL LEAKS UNDER THE CAR
The final symptom of a faulty crankcase breather was the most alarming one.
One morning, when I arrived to work I noticed an oil stain under the car. Not that big but big enough for me to start worrying.
When I checked it, there was engine oil dripping from the crankcase (at least that’s where it seemed to be coming from).
Not a serious leak, rather a very slow dripping.
Another characteristic was that the oil wasn’t worn and black colored (like it would’ve been if it had leaked directly from the crankcase for instance) but rather seemed and smelled much like it was new.
SOLUTION TO A CRANKCASE BREATHER PROBLEM
When the oil leak appeared it was time to take action.
Since I’m a DIY guy the moment I had spare time, I took the engine cover off and made an inspection.
If you want to learn how to take of an engine cover, click here for a separate article on that topic.
On the Skoda Fabia, the crankcase breather is located on the right-hand side (looking from the driver’s seat) near the firewall. A bit of a lower position but is accessible nevertheless.
From the top of the engine, everything looked OK.
To get a look at the lower side of the crankcase breather, I jacked up the car, secured it, and went under to check for any anomalies. Low and behold, the leaking engine oil was coming from the lower part of the breather and was dripping on to the crankcase.
Before I draw any conclusions I also checked:
The hose that leads from the crankcase breather to the throttle body
Electric connector to the PCV valve
The PCV valve (positive crankcase ventilation valve) is a crucial part of the system as it controls the flow of crankcase gases entering the intake system.
Both were as good as new. The electric connector sat in tightly and was free of rust and filth. Also, the hose was in good condition and was gunk-free.
By then the cause of the problem was pretty clear. Buying a new crankcase breather seemed imminent.
From what I could see, the whole part was made out of durable plastic. It didn’t seem friendly for any kind of opening, cleaning, or repair (this proved to be true later on).
Since I lacked the time to make the replacement myself and the part wasn’t immediately available I had to seek the help of a professional mechanic.
When I arrived, I told everything that I’ve noticed and all of the symptoms.
Later the mechanic came to the same conclusion and the whole part was replaced. The oil leak was caused by a faulty gasket on the breather itself.
Although only the gasket was faulty the whole part had to be replaced. I guess this is just the present nature of the industry. Complete replacement is emphasized much more than repair. Such is the build and the price of them.
You can perhaps dismantle and clean it but returning the parts in place without breaking them and not having leaks seems pretty unlikely.
This was the case with the Fabia, but perhaps with other cars, the system is less complicated. Definitely worth the check before buying a whole new part.
HOW MUCH DOES A CRANKCASE BREATHER REPLACEMENT COST?
The whole job, part plus labor cost me about 80 Euros.
The job took a couple of hours. All in all, not that much of a fuss.
Of course, this price is for an older (2004) lower segment car and is certainly more expensive for newer or premium-class cars.
Regarding other cars, the price will vary from country to country depending on things like the popularity of the car brand, availability of parts, labor prices, and else.
Also, an important issue to consider is the accessibility of the crankcase breather. The more inaccessible it is, the higher the labor price gets.
When mentioning costs (or rather reducing them) it would be fair to mention the possibility of a DIY repair.
In my opinion, it is possible. It all depends on your skill level regarding car repair and the car model you own.
In the case of the Skoda, it involves taking off a couple of screws, taking off, and returning a hose and an electric connector. Pretty simple.
In some cars, it’s even easier but on some, it may be more complicated.
The best advice on this part is to make a good assessment of the whole repair before you start. Don’t start anything you can’t finish.
Don’t be surprised if you conclude that you can’t do anything. Most modern engine bays are crammed and full of intertwined systems that demand a lot of dismantling until you actually reach the part.
If this is the case with your car, I would recommend professional help or be prepared for a lot of, in most cases, nerve-wracking work.
What you can certainly do on your own is check the crankcase breather hose, electric connector to the PCV valve, or the valve itself.
Check for cracks, loose hoses, bad electric connection, stuck or faulty PCV valve, clogs caused by gunk, etc.
Check the crankcase breather and PCV valve from time to time. Especially if it’s a less complicated system and easily accessible.
If you can’t do it yourself, ask your mechanic to do it for you. Cleaning or replacing this part will mean the world to your engine, both in terms of functionality and longevity.
Also, be careful that the initial symptoms don’t send you on a wild goose chase. They can mimic problems caused by other systems (like the ignition system, the throttle body, etc).
Perhaps the most important thing is to react on time and when the first symptoms appear.
Otherwise, it may cause serious damage to the engine.
Written by: Sibin Spasojevic
Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com
CRANKCASE BREATHER SYMPTOMS AND SOLUTION VIDEO