but why engine need a "fresh" air from intake manifold? Thats not enough to release combustion gases ( which are in higher pressure) through the PCV valve into manifold? Why on this diagram, cranckase is conected with manifold (on left side) with no valve??! cant understand. Thats mean, combustion gases are all time evacuated into manifold...please explain me someone. Yes im totally newbie.
Dealership said to connect oil catch can to driver side vent and pcv passenger side to oil catch then plug up air intake hole barb and the hole on the intake manifold becuase i am losing oil said catch can is routed wrong any suggestions ?
I had a small oil leak that the clowns at Firestone Auto claimed were leaking valve cover gaskets at $300 a piece, front and rear. Needless to say their diagnosis was bogus. I ignored it until I saw this video. So it was my PCV valve that caused the oil leaks, as I was too find out. Needless to say I have dropped Firestone from my list of service stations to depend on. My car is 12 years old and runs good, with 170k hard miles on it. Thanks! I never would have guessed the PCV valve to cause the oil leaks.
This video solved answered two questions of mine that have kept my 1979 302 engine from working properly all this time. An old timer told me this was probably what was going on but I didn't understand how this system worked. Thanks for making this video...saved me a ton of time and frustration!
I would like to add a little to it. The bore distortion will also cause high blow-by. It is seen at high RPM and high load condition. Secondly the every PCV system has reverse flow condition when the crankcase pressure become positive. Normally It happens when engine operates above 5000rpm with wide open throttle. The pressure in the intake manifold is close to atmosphere so the suction in the fresh side is greater than dirty side PCV. The blow by gas starts flowing out through the fresh hose to induction pipe.
I thank you for this video, you solved my mysterious oil leak when I ran my engine hard ( abc 383 stroker ) I don't know when or why I eliminated the air intake for my pcv system , after I watched your video I realized what I had done. I restored the air in and now problem solved !!! no more oil leaks !!! thanks again
Excellent, thanks. So many people stand in front the engine in their car and attempt to describe the system, and the info is hard to organize and absorb into my little, teeny tiny brain. If they make mistakes (not uncommon), it's just that much worse. Your diagram and presentation are thorough and clear.
Thank you for this! I already knew what the PCV valve was for but I had no idea why there was a second hose on the other valve cover. After watching your video I now know that its just a fresh air source to aid flow for the pcv valve
There are so many things that cause engine problems but I think if I just try cleaning these suction tubes and replacing my PCV valve it might fix or at least prevent so many problems...thanks for the great video
I went to dealership they said to connect crankcase hose to one side of oil catch can and the pcv valve hose to one side of oil catch they then said to block off the intake hole on the block and the barb hole that sticks out of the cold air intake said that will solve my oil consumption problem.
Can someone help me understand why the PCV valve is in the valve cover and not the crankcase? Surely if you’re trying to ventilate the crankcase the valve should be in the crankcase? Or how do the crankcase blow by gases make there way to the PCV valve in the valve cover. Just trying to understand it better, cheers!
I think you may have missed a 5th cause. It is that of worn or loose valve guides. I have experienced this in several older V-8 and V-12 engines. But thank you for a clear explanation of the basic system.
The information you convey is very helpful. Unfortunately, the tail end of the video cut out where you were going to go through your diagram of the pvc value. This is what i needed.
Excellent presentation. It has helped me discover I am missing a pcv valve on one of my valve covers.....it just has a sealing twist type cap. The other valve cover is connected to the base of the air filter. This means the vacuum suction isn’t working properly. My question is Where should the hose from the pcv be connected.....to manifold vacuum at base of carb or to intake manifold vacuum further away from carb
So is this bad happening?? I have a wrf 450 2005 model that has a hose attached on the upper of the valves cover and goes free down on the footpegs attached to nowhere and I noticed too much air was coming off this hose as the engine worked.... Is this normal or what??
blow by can be caused by bad gaskets too but the 2 most important things that a pcv vlv does are that it will lower your engine operating temperatures (bc of the oil moisturizer action & active ventilation of the inner engine) and it will lower emission gases @ tail pipe (lower temps translates to a better op range + a better eng performance) .. as a bonus, it will preserve better your cat conv, surrounding metals that activates on the system, save you gpm, preserve gaskets, seals & other related metals & chemicals that seal the eng; and of course your o2 snsrs as well 💲
2:00 If I only have fresh air coming from the carb air filter and not the tube on the valve cover..... 1) how many push in breathers / air filter pod you can place in a valve cover to obtain that cold air into the engine? 2) can you place breathers on the valve cover around where the PCV valve is installed.
Hi !!!!! According to your diagram there ,the PCV air circulates from the air box through the crank case and then to the PCV valve. Now I learned that blow-by causes oil to get into the air-box, but how does it get into the air-box if the air circulates from the air-box to the crank-case? Plus the crank-case breather is between the air-box and the valve cover too. On my 2001 dodge ram van anyway. I'm a little or more than a little confused about that!!!
the only improvement to this system would be the installation of a canister above the PCV so that oil is trapped and gases can continue on. Oil contaminates the valves.
For first time ever, Replaced all the tubes, grommet, O Ring, Cleaned and Sealed Breather Box on my 95 Honda Civic. It definitely seems to have more Power etc... What are the benefits to the car when cleaning breather box, sealing and replacing all the parts to it? Better Gas Mileage? More Horse Power? I also changed timing belt, water pump, tensioner, Crankshaft seal and camshaft seal and Valve Cover seals..... Car Definitely has better response, smoother and seems to have more power.... Does cleaning and replacing parts to Breather box do all of this or is this from changing the timing belt? Thanks!
Thanks for the explanation. However, there are a few things I did not quite understand after 1:45. Engine creates a vacuum sucking fresh air in from the intake manifold and the crankcase blow-by wants to escape due to high pressure by the compression. How does vacuum and pressure occur at the same time? Or are they sequential? Also, if the fresh air is continuously sucked in due the vacuum created by the engine why should there be a need for a ventilation on the other side while the intake manifold is supplying fresh air into the engine at all times?
I don't understand it all myself but I know that vacuum is created by the pistons moving downwards creating suction, so there is a vacuum in the intake pathway. I don't think there would be much pressure in the crankcase unless it was completely sealed. If the pcv valve is clogged the crankcase will vent from the fresh air opening on the opposite valve cover.
Matt Denson - according to wikipedia: Manifold vacuum Not to be confused with Vacuum manifold. Manifold vacuum, or engine vacuum in aninternal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere. Manifold vacuum is an effect of a piston's movement on the induction stroke and thechoked flow through a throttle in the intake manifold of an engine. It is a measure of the amount of restriction of airflow through the engine, and hence of the unused power capacity in the engine. In some engines, the manifold vacuum is also used as an auxiliary power source to drive engine accessories and for the crankcase ventilation system. Manifold vacuum should not be confused with venturi vacuum, which is an effect exploited in carburetors to establish a pressure difference roughly proportional to mass airflow and to maintain a somewhat constant air/fuel ratio. It is also used in light airplanes to provide airflow for pneumatic gyroscopic instruments.
Loved the explanation - very clear. Only suggestion I'd make is to get a better microphone. It will improve the sound quality by a lot and increase the quality of your videos even more. Subscribed!
I have doubts, The hose from the PCV goes to the carburetor or can be conected to the base of the air filter assembly? The 2nd, the ventilation on your other side of the drawing, Is it the other valve cover breather? I suppose that both sides work in the same way= expelling gases: blowby, with 1 PCV is enough or there must be in the 2 sides? Isn´t it recommendable: proper to connect the hose from the PCV directly to the intake manifold? I´ll wait for your kind response
No. The video is correct , one hose is a breather hose , drawing fresh air after the air filter . the other hose is connected to engine vaccum past the throttle . if both hoses were to be gas exits , they would be both past the throttle body , no need to direct one to the air filter unless we like oil soaked filters . the size of pcv valve varies , so no need for 2 hoses, just put the correct one
Can i ask something? I still dont understand why does the pcv valve drag the vaccum through the cam shaft cover? Why does the fumes have to go through there when they could be easily routed out of the crankcase only?
I think it's done that way because the valve cover is the highest point on the engine. If the opening for the valve were lower, it could leak oil through the hole.
Nice explanation, I have a 60 impala that the prior owner installed a 350 with double hump heads, performance com and no pcv system. My engine leaks from the newly installed valve cover gaskets and smoke comes from my passenger side valve cover breather. I will install a pcv system but trying to determine the correct pcv for my double hump heads(i believe they came from a 68 camaro 327) thanks again.
Are all PCV valves The same flow rate So the question I ask if I replace my plastic PCV valve with a billet Aluminum Will that work at the same designed flow rates as my one for my vehicle ?
What if the layout was exactly as shown except there was no valve, just an open hose from the valve cover to carb vacuum? Would this be detrimental to the engine?
Great video . In a turbo engine can pcv oil vapours enter the intercooler and later create oil accumulation within the intercooler? Where is the pcv hose connected to in such cars? Is it after the intercooler?
So when an engine is running, there is at least a mild pressure in the crankcase. In a naturally aspirated engine, there will always be at least a tiny amount of vacuum from the opening of the intake system all the way to the intake valves. How then does fresh air flow from the air intake, where there is vacuum, into the breather, where there is pressure?
if PCV is blocked , oil would leak from the engine ,right?, But wouldn't the blow by goes out the breather side ? instead of leaking from seals or gaskets ?
I have a gm 3.8 with a water leak up the the pcv channel in the rear cylinder head. Does that mean my head gasket is done? Is my block cracked? Water and oil are definitely mixing...
This is also why you DON"T make high compression turbo cars. All that blow by goes directly to your oil, causes sludge, and a catch can won't be enough to fix it.
No, only when the engine is not running (no vacuum) or when backfire occurs (pressure). Pause the video at the very end and have a closer look at the drawings to see flow characteristics and metering function in addition. Too bad that the detailed explanation has been cut off of the video!
Great vid. If you take the oil filler cap off for a few seconds while the engine is running, does it affect the pcv valve, or cause an oil smell outside of the engine?
Where the vacuum is created in the inlet manifold or crank case ??i think vacuum must be created in inlet manifold so that pcv valve sucks the blowby gases from the crank case and sent it into the combustion chamber again am i right??
Truth set u free - according to wikipedia: Manifold vacuum Not to be confused with Vacuum manifold. Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere. Manifold vacuum is an effect of a piston's movement on the induction stroke and the choked flow through a throttle in the intake manifold of an engine. It is a measure of the amount of restriction of airflow through the engine, and hence of the unused power capacity in the engine. In some engines, the manifold vacuum is also used as an auxiliary power source to drive engine accessories and for the crankcase ventilation system. Manifold vacuum should not be confused with venturi vacuum, which is an effect exploited in carburetors to establish a pressure difference roughly proportional to mass airflow and to maintain a somewhat constant air/fuel ratio. It is also used in light airplanes to provide airflow for pneumatic gyroscopic instruments among other items ..
Hi sir. I dropped the old pcv valve grommet inside of my honda city 2011. I can't get it anymore. Would there be any issue? Hoping for you expert opinion. Thank you.
I have a question, the passages side valve, on top of valve cover what is that called , I think its where the fresh air comes in, my question is can that passenger side valve be replaced i can't find a video about it, its just a hose that connects to something there on top of valve
why is it said that if pcv valve will fail, the oil cap will not come out easy ? I mean inside the crankcase there has to be pressure, if pcv fails, there should be pressure inside crankcase so cap should be easy to remove
You would start blowing out gaskets, like the rear main seal and valve cover and oil pan gaskets Also your fresh oil will get contaminated fast with moisture and combustion blow-by. Cars have always had breathers. At one point they were just a draught tube that ran from the crankcase down along the back of the engine to near the road. But there was still a Breather cap on a Rocker cover or on the intake valley or pushrod cover on the side of the engine.
To understand: what force cause the PCV spring works (open/close)?... the vacuum or the pressure of the crankcase? .... because I have problem: I saw high vapor come out from the oil cap. wonder why! ..... I replace the pcv valve 2 month ago. some one told me maybe i have blowby problem. I know what cause too much blowby, but before go throw the piston ring I wonder if with a oil catch can can fix this. But my question is, the pcv valve maybe is defective and no working properly to release that pressure??? PLEASE HELP !!!
