Guide to the Volvo PCV system (With video).

[Gabe244]

This article is specifically written to cover the mid 80’s 200 series B2xx cars, but many of the components and information included is applicable to later, earlier or different models also.

Note: Much of this information is included in the video.

PCV FAQ.

What does PCV stand for?
PCV stands for Positive Crankcase Ventilation.

What does the PCV system do?
The PCV system lets the combustion blow-by escape from the crankcase. It does this by giving the gasses a place to escape and this is aided by the vacuum in the intake manifold / pre turbo piping. To over simplify it, the PCV system sucks out blow-by from the engine.

What is blow-by?
Blow-by is the gasses and vapours that escape from the combustion chamber, past the rings and into the crankcase.

What does the PCV system comprise of?
The main component of the PCV system is an Oil Separator or “breather box”, to let the oil vapour from the blow-by circulate back into the sump. This is then connected to a device called a Flametrap*, which stops backfires from the intake manifold from entering the crankcase, causing an explosion. The Flametrap consists of a hose with a tiny strainer in it (around the size of a coin), which is then connected to a plastic divider which allows two hoses to connect to it. These hoses are then connected to back into the intake manifold. * On turbo models the flametrap is omitted, and instead the breather box is connected via a hose to the air intake before the turbo.

What are the symptoms of a clogged PCV system?
Generally the oil seals in the engine will start leaking oil. The most common ones to leak are the cam seal, the oil filler cap and sometimes the rear main seal. Other symptoms include smoking from the engine bay whilst driving (Due to the oil filler cap seal leaking oil onto the exhaust) or sometimes the oil dipstick pops out (too much pressure in the crankcase).

How can I test my PCV system?
The usual test is just to undo your oil filler cap whilst the engine is running and see if it gets sucked down onto the cam cover. If it is, then there is vacuum in your crankcase and the PCV system is working perfectly. If it isn’t then it means that your crankcase has pressure inside it, and your PCV system needs servicing.

How can I clean my PCV system?
The first thing you want to do is to clean all the easy …..easier to reach parts and see if that fixes your problem. If that doesn’t, then the breather box will need to be removed and cleaned/replaced. To start cleaning you’ll first need to locate your breather box. The breather box is located on the side of the block, in between the 2nd and 3rd runners of the intake manifold.


Here is the breather box.

Then you want to find the hose that runs into the top of it. In N/A cars, this is the flametrap. You want to pull that off the port on the breather box, and follow the hoses to where they meet the manifold. Once you’ve found out where those hoses go, pull them off, and clean them out with some carb cleaner or replace them with new ones. Then clean out the respective hole/nipples on the manifold, so you can clearly see through them. Remove the nipple/port from the manifold if possible before cleaning them. If you’ve decided to keep the original flametrap and just clean it out, then take it apart (cut the zip tie holding the plastic divider to the hose) and poke out all the holes in the flametrap with a needle/nail, so air can flow through it. Also clean out the plastic divider. Then refit all the parts to the engine, using a new zip tie on the flametrap. Make sure that the hoses are in the right place, then start up the engine and repeat the test with the oil filler cap. If it is still not sucking the cap down then you’ll need to clean out the breather box. The breather box is held to the block with 2 bolts and sealed against the block with an o-ring. Removing the breather box usually requires removing the Intake manifold and air flow plate (for k-jet models) or nothing at all if you have an LH car. When removing the breather box make sure that the hose going into the sump is not removed too. DO NOT REMOVE THE HOSE TO THE SUMP. Refitting that hose requires the removal of the oil pan. To clean the breather box, I use a mallet (rubber), a wire and lots of degreaser. Start off by tapping it with a mallet to remove as much carbon deposits as possible, then scratch around in there with the wire, and finally soak it in degreaser. Repeat all the steps until it’s clean and free from obstructions. Once this is done check that the hose to the sump isn’t blocked. To do this, I use a long piece of wire to check for obstructions and remove them if necessary. Then I follow it down with some degreaser. HOWEVER MAKE SURE THAT YOU EMPTY THE OIL BEFORE USING DEGREASER AND CHANGE THE OIL IF YOU REMOVE ANY CARBON DEPOSITS FROM THE HOSE. Also, pour some oil down the hose to make sure that there is absolutely no degreaser left in the engine. If however the hose is unobstructed and no deposits had to be scraped off then you can leave the old oil in there. Once all that’s done, refit all the components making sure to use a new o-ring on the breather box. Now enjoy your perfectly clean PCV system.

How can I make the stock system better?
The majority of the stock system can be removed if you fit either a catch can, or let the breather box vent to the atmosphere.

What is a catch can?
A catch can is just a container to collect all the blow-by from the breather box. To connect the catch can, just run a hose from the port on the breather box to one of the ports on the catch can. Then on the other port of the catch can, either a mini air filter can be fitted (Which is against EPA regulations in most civilised countries), or a line back into the intake manifold can be fitted. In turbo models, this line has to go back into the intake, pre-turbo. (see examples below).

Some catch cans are “baffled” which makes the vapour condense in the can better. If your can is not baffled you can put some stainless steel scourers into the can (optional).

Catch cans seem like a lot of work, what is the other option?
The other option is just to vent the vapour to the atmosphere. This is generally achieved by running a hose from the port on the breather box, to the underside of the car. This is not recommended because it is bad for the environment, and it leaves drops of oil on your driveway. Most drag strips will also have an issue with you dripping on the track, so some people chose to route the end of the hose into a soft drink bottle instead, just temporarily.

If the breather box is likely to get clogged, why cant I remove it and replace it with a bolt on port? You could, if you don’t mind emptying your catch can every couple of days.

The fluid in my catch can, looks like murky water. What’s going on?
This is normal. Water is a by-product of the combustion of a hydrocarbon. This is also why exhausts tend to rust from the inside out.

My catch can is vented to the atmosphere, and it fills up really quick (Couple of hours or a few days), are my rings shot? Not necessarily. You should find that by recirculating the catch can back into the intake, it should stop filling up so fast.

Where can I get PCV related parts?
Parts can be had through IPD.
http://www.ipdusa.com/Volvo-200/Engi...9-258-260-847/ (IPD’s PCV section for the 200 series.)



PICS


Catch can installs.





Picture of recirculation pre turbo.


Modified breather box for added flow.



Down the dolphins throat.



The video will be added tomorrow morning once its up on U-tube. Its pretty casual cause I didnt have all day to film it and edit it, so excust the ocasional pause whilst i think of the right words .

[SteveMD]

Ha, ha, I love this article. Well done, young fellow. I'm putting my hat on so I can tip it to you!

[Freq]

Looking forward to it. I don't/didn't know anything about the PCV system.

[WindowsBreakerG4]

Nice writeup. lol at the dolphin

[Andrew9578]

You mentioned about just venting the PCV to atmosphere and that it is bad if you go to the track because of the oil dripping on the track. How much oil would come out of the hose? Also, will venting it to the atmosphere hurt the engine in anyway? I don't want to have a seal leak because there is no vacuum present.

[Gabe244]

Venting to the atmosphere isnt ideal because then there is no vacuum in the crankcase. That being said, a great number of people do it anyway without problems. The amount of oil that comes out of the hose is usually quite small (with my catch can its just gas), however this depends on how clogged your breather box is, and how well your rings seal. Personally, if venting to the atmosphere is what you want to do, then do it, and swap to a catch can later if you have any issues. Be carefull as venting to the atmosphere is likely to be illegal in your area, so try to hide the hose as best as possible.

[SlowRide]

Dolphins can be used to replace most of the emissions parts including catalytic converters and charcoal cans

Seriously though, good right up.

[ZVOLVO240]

well done gabe. you beat me to it. I was going to do a write up on this. damn

[Gabe244]

Sorry i havent got the video up yet. Youtube didnt want to upload it last time i tried. And thanks everyone for the comments .

[Texas240]

Fantastic right up, learn something new everyday. Gabe. I have a few questions regarding the car with the dolphin.. Lol.. Tehehe. To funny. The two clear rubber tubbing. They are just being rerouted from the breather box to the catch can back to the breather box.. right?

Can I get a distant picture of this so I can see how you routed your tubing. Thanks

[Gabe244]

Im afraid the dolphin car isnt mine . However what they did was run two hoses from the breather box into the catch can, then had a mini filter on the catch can. The breather box for that car is also pictured above.

[Texas240]

That breather box looks different them OEM unless Im forgetful

[Gabe244]

Yeah, he added an extra nipple.

[Texas240]

Originally Posted by gabetheunicycleman

Yeah, he added an extra nipple.

That explains it...

[WindowsBreakerG4]

I have a question for someone running more then 1 port back to the intake, did people add a second port to your intake piping or did you just put a Y in line? Or has no one gone down that route?

[Volvo244GLE]

nice article mate

[superboosted]

Sweet,my motor is the recirculation pre turbo pic

[smokeyfan1000]

Might want to mention that OEM Volvo flametrap hoses last a *whole lot longer* than any of the aftermarket ones, or point them towards OEM parts.

I bought an MTC flame trap hose & it cracked in 3 weeks without ever having even cranked the engine

And most places are selling the MTC hoses.

[volvorod85]

Good info, But you need to make it knows that in places like the USA, especially California and other stated and areas that have adopted our smog rules, this technically isnt legal, and there is a god chance you will fail the smog check due to a modified PCV system.

I hate to rain on the parade, especially if done right, upgrading the PCV system properly without venting to the atmosphere, and keeping the crankcase gasses in the motor and burned properly with no oil being spilled on the ground, properly caught in a catch can and disposed of properly makes for better emissions. But the state does not see it this way unfortunately and well, it sucks.

So just beware of that fact, otherwise...good write up

Mark

[VQ]

http://www.pbase.com/stealthfti/pcv



Other Ways to improve PCV breathing.

[face_the_heat]

^ love this idea. I wonder what the power difference is between venting to atmosphere versus catch can. On one side there is fresh air,but with no vacuum aid. Then dirty air, but lower crank case psi due to vacuum. Anyone ever dyno this?

[towz-T]

so, all catch cans with a filter on top vent into the atmosphere?
and why would you put a filter on it, or is it when the turbo is spooling it could also draw air in from that point?

[dalek]

Originally Posted by VQ

http://www.pbase.com/stealthfti/pcv
Other Ways to improve PCV breathing.

And you can hump your redblock at the lights!

[Volvo240BLUE]

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