Why oil in the intake air charge is BAD...
01-11-2010, 12:14 PM
#22
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TLewis4095 - I have a question for you..... I really want to cap off the hose from my passenger side head to the Throttle body. I have a LS1 motor w/ LS6 valley. I bought a Revx catch can. You see any problems with me capping both ports on passenger side head and the port on the throttle body. Then run a hose from top of catch can to rear of drivers side head and a hose from side of can to front of intake manifold and put a breather on the oil fill cap?
None of the drawings show capping the passenger head to TB but i get oil reversion through that tube then it goes into my intake. I'll still be venting the crankcase through the oil fill cap and drawing all the gases and oil to the top of the can from drivers side head.
Please advise!!!!!
None of the drawings show capping the passenger head to TB but i get oil reversion through that tube then it goes into my intake. I'll still be venting the crankcase through the oil fill cap and drawing all the gases and oil to the top of the can from drivers side head.
Please advise!!!!!
01-11-2010, 03:05 PM
#24
TLewis4095 - I have a question for you..... I really want to cap off the hose from my passenger side head to the Throttle body. I have a LS1 motor w/ LS6 valley. I bought a Revx catch can. You see any problems with me capping both ports on passenger side head and the port on the throttle body. Then run a hose from top of catch can to rear of drivers side head and a hose from side of can to front of intake manifold and put a breather on the oil fill cap?
None of the drawings show capping the passenger head to TB but i get oil reversion through that tube then it goes into my intake. I'll still be venting the crankcase through the oil fill cap and drawing all the gases and oil to the top of the can from drivers side head.
Please advise!!!!!
None of the drawings show capping the passenger head to TB but i get oil reversion through that tube then it goes into my intake. I'll still be venting the crankcase through the oil fill cap and drawing all the gases and oil to the top of the can from drivers side head.
Please advise!!!!!
Yes, your correct on both. Post up your results!
01-13-2010, 07:06 AM
#25
If you really want to stop the oil from getting in the intake, don't hook anything from the crankcase to the intake. Run breathers, and be done with it.
That, will stop ALL oil from getting into the intake, and stop the issue 100%. Changing oil every 3000 miles, is more then adequate to deal with any contaminents that might build up in the motor, key is to change it while it's hot, so that everything is in the oil and not sitting somewhere in the motor.
Also eliminates the need to buy a catch can, breathers are generally alot cheaper to buy
That, will stop ALL oil from getting into the intake, and stop the issue 100%. Changing oil every 3000 miles, is more then adequate to deal with any contaminents that might build up in the motor, key is to change it while it's hot, so that everything is in the oil and not sitting somewhere in the motor.
Also eliminates the need to buy a catch can, breathers are generally alot cheaper to buy
01-13-2010, 11:53 AM
#26
If you really want to stop the oil from getting in the intake, don't hook anything from the crankcase to the intake. Run breathers, and be done with it.
That, will stop ALL oil from getting into the intake, and stop the issue 100%. Changing oil every 3000 miles, is more then adequate to deal with any contaminents that might build up in the motor, key is to change it while it's hot, so that everything is in the oil and not sitting somewhere in the motor.
Also eliminates the need to buy a catch can, breathers are generally alot cheaper to buy
That, will stop ALL oil from getting into the intake, and stop the issue 100%. Changing oil every 3000 miles, is more then adequate to deal with any contaminents that might build up in the motor, key is to change it while it's hot, so that everything is in the oil and not sitting somewhere in the motor.
Also eliminates the need to buy a catch can, breathers are generally alot cheaper to buy
Hardly, but make sure you do it that way. Ignorance is bliss, isn't it?
Every time your motor is started and gets up to operating temp the unburn't fuel, moisture, suferic acid, and the rest of the crankcase crap flashes off to vapor. If not pulled by a vacuum source and flushed with filtered fresh air it re-condenses back into the crankcase & coats internal parts. That is critical to long engine life. For those that care about engine life in their pride & joy you must evac the crankcase properly. 405hp_Z06 has numerous oil analysis showing the acid build up & increased wear even changing oil at frequent intervals.
On our Top Dragsters & Super Comp cars we run belt driven vacuum pumps to evac and then we change oil every race or so.
So again, run your motor as you please but posting stupid info like that is irresponsible.
How about you post up your qualifications to make such a statement?
01-13-2010, 12:27 PM
#27
Here's some for ya:
I've had oil analysis done several times, both before removing the pcv and after, and at the interval that I change the oil, in my case being a race car, every track trip, there's a absolutely no change in the volatile's that you are talking about. I've tried this on a street car that had the oil in it for 3 months, not 3000 miles, but 3 months.. and the change was very minimal. That's enough for me to say that the minimal blow-by that the engine's have, is enough to vent the fumes of said contaminants out of the engine.
A vacuum pump, on a race car has a different purpose other then pulling the contaminants out. It draws a vacuum on the crankcase, helping rings seal, helping to control the oil in the engine as well... so it's purpose really has next to nothing to do with the crankcase contamination, it just happens to do that as well. I actually have a vacuum pump sitting here waiting to go on when the motor comes apart, which I'll be happy to take pictures of for you, being that it's been together for 4 years, probably means that the corrosive contaminants MUST have eaten the internals all to hell right? I should expect to see the rods eaten away, crank eaten away, bolts all corroded, etc.
Also worth mention, is the following facts:
A. for YEARS, before emissions standards came along, crankcases were vented to the atmosphere. This never stopped cars from running fine for years, hell every old car you see at a car show doesn't have a pcv, they're vented... that should tell you something.
B. You used to sell these when you were a sponsor, and I would suspect that this is a ploy to try to get some type of sales going again, and if I hear of one back door sale... you'll be out of here.
Hope this helps.
I've had oil analysis done several times, both before removing the pcv and after, and at the interval that I change the oil, in my case being a race car, every track trip, there's a absolutely no change in the volatile's that you are talking about. I've tried this on a street car that had the oil in it for 3 months, not 3000 miles, but 3 months.. and the change was very minimal. That's enough for me to say that the minimal blow-by that the engine's have, is enough to vent the fumes of said contaminants out of the engine.
A vacuum pump, on a race car has a different purpose other then pulling the contaminants out. It draws a vacuum on the crankcase, helping rings seal, helping to control the oil in the engine as well... so it's purpose really has next to nothing to do with the crankcase contamination, it just happens to do that as well. I actually have a vacuum pump sitting here waiting to go on when the motor comes apart, which I'll be happy to take pictures of for you, being that it's been together for 4 years, probably means that the corrosive contaminants MUST have eaten the internals all to hell right? I should expect to see the rods eaten away, crank eaten away, bolts all corroded, etc.
Also worth mention, is the following facts:
A. for YEARS, before emissions standards came along, crankcases were vented to the atmosphere. This never stopped cars from running fine for years, hell every old car you see at a car show doesn't have a pcv, they're vented... that should tell you something.
B. You used to sell these when you were a sponsor, and I would suspect that this is a ploy to try to get some type of sales going again, and if I hear of one back door sale... you'll be out of here.
Hope this helps.
01-13-2010, 01:02 PM
#29
Why are you tryin to have a dick measuring contest? Thats what I'm curious about.
Did he mentioned anything about wanting people to buy anything of his? No, he said buy whatever you want, but a catch can of some sort is a good idea. And then provided his knowledge on the topic. I see absolutely nothing wrong with that.
You can look at it like a sales pitch if you want but thats just a dick move until he posts something closer to tryin to drum up sales.
Oh, and I do not see a race car as a good example on this topic. I'm sorry but I dont change my oil after every trip to the track. I drive there, run, drive home & then drive it daily 300+ miles a week. And change the oil every 3000 miles. Your not gonna see build up on a race engine constantly flushed with fresh oil as you are a daily driven car racking up the typical 20k miles a year.
I say stop arguing until he blantly makes a sale pitch thread or post. I enjoy reading information, not drama.
Did he mentioned anything about wanting people to buy anything of his? No, he said buy whatever you want, but a catch can of some sort is a good idea. And then provided his knowledge on the topic. I see absolutely nothing wrong with that.
You can look at it like a sales pitch if you want but thats just a dick move until he posts something closer to tryin to drum up sales.
Oh, and I do not see a race car as a good example on this topic. I'm sorry but I dont change my oil after every trip to the track. I drive there, run, drive home & then drive it daily 300+ miles a week. And change the oil every 3000 miles. Your not gonna see build up on a race engine constantly flushed with fresh oil as you are a daily driven car racking up the typical 20k miles a year.
I say stop arguing until he blantly makes a sale pitch thread or post. I enjoy reading information, not drama.
01-13-2010, 01:04 PM
#30
Pulling a vacuum on a crankcase certainly helps with removing contaminated vapor. Breathers are located on top of an engine, contaminated crank vapors are heaviest in the bottom of the engine. Some thing needs to circulate them out/through the engine - vacuum does that quite well.
Last time I checked there was about 14.5 psi of atmospheric pressure in most areas, of course this can change by a few psi depending on altitude making it hard for those vapors to leave those open breathers unless you have more pressure than that in your crank case!
These engines are plagued with oil vapor/PCV issues. A catch can is great idea for a street car. A vacuum pump with a catch can is better idea, but a little costly for the average enthusiast.
To the OP, sometimes you can't win arguments with the interent 'experts'
Nice list of accomplishments BTW!
Last time I checked there was about 14.5 psi of atmospheric pressure in most areas, of course this can change by a few psi depending on altitude making it hard for those vapors to leave those open breathers unless you have more pressure than that in your crank case!
These engines are plagued with oil vapor/PCV issues. A catch can is great idea for a street car. A vacuum pump with a catch can is better idea, but a little costly for the average enthusiast.
To the OP, sometimes you can't win arguments with the interent 'experts'
Nice list of accomplishments BTW!
01-13-2010, 01:05 PM
#31
Why are you tryin to have a dick measuring contest? Thats what I'm curious about.
Did he mentioned anything about wanting people to buy anything of his? No, he said buy whatever you want, but a catch can of some sort is a good idea. And then provided his knowledge on the topic. I see absolutely nothing wrong with that.
You can look at it like a sales pitch if you want but thats just a dick move until he posts something closer to tryin to drum up sales.
Oh, and I do not see a race car as a good example on this topic. I'm sorry but I dont change my oil after every trip to the track. I drive there, run, drive home & then drive it daily 300+ miles a week. And change the oil every 3000 miles. Your not gonna see build up on a race engine constantly flushed with fresh oil as you are a daily driven car racking up the typical 20k miles a year.
I say stop arguing until he blantly makes a sale pitch thread or post. I enjoy reading information, not drama.
Did he mentioned anything about wanting people to buy anything of his? No, he said buy whatever you want, but a catch can of some sort is a good idea. And then provided his knowledge on the topic. I see absolutely nothing wrong with that.
You can look at it like a sales pitch if you want but thats just a dick move until he posts something closer to tryin to drum up sales.
Oh, and I do not see a race car as a good example on this topic. I'm sorry but I dont change my oil after every trip to the track. I drive there, run, drive home & then drive it daily 300+ miles a week. And change the oil every 3000 miles. Your not gonna see build up on a race engine constantly flushed with fresh oil as you are a daily driven car racking up the typical 20k miles a year.
I say stop arguing until he blantly makes a sale pitch thread or post. I enjoy reading information, not drama.
01-13-2010, 01:14 PM
#32
Mike and helicoil.. I've had enough of these motors apart, both ones that used the pcv, and breathers to safely say that if you see the buildup that ends up in the heads, valves and pistons from an engine that had a PCV on it vs one that had breathers on it.. you'd quickly ditch the entire PCV.
Engines with alot of miles on them,, over 80 K that had breathers on them for their entire life had a substantially cleaner top end, no need to flush the intake out, ports were cleanable with a rag and some carb clean etc. The crankcase, didn't show any signs of buildup anywhere that was any different then a PCV equipped engine.
You can debate it all you want, but try ripping a motor apart, even one with the mystical catch can, and see what you find. Then when you rebuild it or whatever you have it apart for, try throwing a filtered breather on it and see what it looks like afer 20 to 30K Pull the oil pan too, and see if there's anything in the pan that is worth making mention of.
I already know what you will find, which is where my statements come from.
Bottom line, change the oil and filter often enough, and make sure that the car was hot when you drained the oil, which is more important to keeping an engine clean then most people know and you will not have a problem. Driving 3000 miles, and changing it is fine for the interval too, that's not leaving the oil in the motor long enough to hav an issue, especially if you're putting 300 miles a week on the car.
01-13-2010, 01:31 PM
#33
Mike and helicoil.. I've had enough of these motors apart, both ones that used the pcv, and breathers to safely say that if you see the buildup that ends up in the heads, valves and pistons from an engine that had a PCV on it vs one that had breathers on it.. you'd quickly ditch the entire PCV.
Engines with alot of miles on them,, over 80 K that had breathers on them for their entire life had a substantially cleaner top end, no need to flush the intake out, ports were cleanable with a rag and some carb clean etc. The crankcase, didn't show any signs of buildup anywhere that was any different then a PCV equipped engine.
You can debate it all you want, but try ripping a motor apart, even one with the mystical catch can, and see what you find. Then when you rebuild it or whatever you have it apart for, try throwing a filtered breather on it and see what it looks like afer 20 to 30K Pull the oil pan too, and see if there's anything in the pan that is worth making mention of.
Engines with alot of miles on them,, over 80 K that had breathers on them for their entire life had a substantially cleaner top end, no need to flush the intake out, ports were cleanable with a rag and some carb clean etc. The crankcase, didn't show any signs of buildup anywhere that was any different then a PCV equipped engine.
You can debate it all you want, but try ripping a motor apart, even one with the mystical catch can, and see what you find. Then when you rebuild it or whatever you have it apart for, try throwing a filtered breather on it and see what it looks like afer 20 to 30K Pull the oil pan too, and see if there's anything in the pan that is worth making mention of.
I have heard enough guys talk about hating the mess that can come along with breathers to make me not even want to try it. It might not be bad on cars only making weekend passes but if those breathers let oil mist out at all, I dont want to be constantly cleaning my pretty powder coated parts. I'd rather just dump a can.
01-13-2010, 01:39 PM
#34
The mess is avoidable, you just have to keep the filter clean. Carb clean it off at least every oil change and you don't have an issue, the filter element just has to be clean enough to catch all the oil.
The catch cans do help the issue, but as long as you are sucking air out of the crankcase, you are going to have something going in the intake that will contaminate the intake charge.
We had several catch cans, from home made ones, to the amw ones that first came out on cars, and even with the cans, after a good 10K on a car there's always a snail-trail leading from the pcv connection inside the intake and in the tb from the line that runs from the valev cover to the TB.
Only way to 100% eliminate the oil from getting into the intake, is to unhook the intake from the crankcase. This, will for sure stop the top end of the motor from becoming a mess. Whether you vent it, run a vaccum pump, whatever it doesn't matter.
The catch cans do help the issue, but as long as you are sucking air out of the crankcase, you are going to have something going in the intake that will contaminate the intake charge.
We had several catch cans, from home made ones, to the amw ones that first came out on cars, and even with the cans, after a good 10K on a car there's always a snail-trail leading from the pcv connection inside the intake and in the tb from the line that runs from the valev cover to the TB.
Only way to 100% eliminate the oil from getting into the intake, is to unhook the intake from the crankcase. This, will for sure stop the top end of the motor from becoming a mess. Whether you vent it, run a vaccum pump, whatever it doesn't matter.
01-13-2010, 03:08 PM
#36
We pull vacuum on our race motors for two purposes, sel the rings (we use a low tension ring if going to pull vac) and to evac the moisture and combustion by-products. But this is not a good comparrison to a street motor.
In the old days (I was born in the mid 50's) motors rarely went more than 75K miles before needing an overhaul (I have been building engines since the late 60's, early 70's). Today we see 200-300k. Part of this is of course better oils & quality control at the manufacturers level, but much of it is due to the much improved crankcase evacuation. Again, use a CCA, Mike Norris, Saikou Micchi, that are real effective. The small ones like AMW are far to small for the vpors to slow enough to allow for the oil to condense & drop out of suspension so it is no surprise you still had ingestion. An oil seperating can has to be close to or greater than 1 qt for a V8 engine's PCV flow to be able to slow enough.
Want to test and see what cans work & what ones are only partially effective? Simply take a clear inline fuel filter and place it on the outlet side between the vacuum nipple & the outlet. You will see with most cans oil still getting through and saturating the filter media. You will NOT on the ones I've mentioned as they are the most effective on the market. That is what so many fail to differentiate when choosing. No market hype, just fact that you can test yourself.
Again, on motor tear downs I do this day in, day out.....and have long before the LS GenIII was released (At Reher Morrison Darin Morgan was doing R&D for GM on the first GenIII heads before any were released). This is not a pissing match on selling anything I design or manufacture, it is sharing knowledge to help fellow members get the most out of & have it last the longest. Go to my posts in general....thousands just answering questions & giving kudo's to supporting vendors.
JL, you are more than able to run yours how you choose, it's your loss, not mine. But to argue this to this extent and cause other to follow your flawed logic helps no one.
In the old days (I was born in the mid 50's) motors rarely went more than 75K miles before needing an overhaul (I have been building engines since the late 60's, early 70's). Today we see 200-300k. Part of this is of course better oils & quality control at the manufacturers level, but much of it is due to the much improved crankcase evacuation. Again, use a CCA, Mike Norris, Saikou Micchi, that are real effective. The small ones like AMW are far to small for the vpors to slow enough to allow for the oil to condense & drop out of suspension so it is no surprise you still had ingestion. An oil seperating can has to be close to or greater than 1 qt for a V8 engine's PCV flow to be able to slow enough.
Want to test and see what cans work & what ones are only partially effective? Simply take a clear inline fuel filter and place it on the outlet side between the vacuum nipple & the outlet. You will see with most cans oil still getting through and saturating the filter media. You will NOT on the ones I've mentioned as they are the most effective on the market. That is what so many fail to differentiate when choosing. No market hype, just fact that you can test yourself.
Again, on motor tear downs I do this day in, day out.....and have long before the LS GenIII was released (At Reher Morrison Darin Morgan was doing R&D for GM on the first GenIII heads before any were released). This is not a pissing match on selling anything I design or manufacture, it is sharing knowledge to help fellow members get the most out of & have it last the longest. Go to my posts in general....thousands just answering questions & giving kudo's to supporting vendors.
JL, you are more than able to run yours how you choose, it's your loss, not mine. But to argue this to this extent and cause other to follow your flawed logic helps no one.
01-13-2010, 03:21 PM
#37
Preach what you want, but I have enough real world exp to know that the can isn't going to be the end all solution to oil in the intake tract that breathers will be... and the breathers aren't going to adversly effect anything anywhere near to the extent that you are making it out to be.
As for engine life, manufacturing tolerances and by far superior lubrication, as well as better design's are why car's are going the distance that they are... it has very little to do with crankcase evap.. crankcase evap didn't come along to get anything out of the crankcase, it was developed to stop the fumes from the engine from going into the atmosphere.. it's a way of reducing total emmissions on a car. It came along, about the same time that cat. converters were required... you've been around long enough you should remember that.
I'll keep my breathers, and will get the vaccum pump on the motor while it's apart, and I will now make a point to take pic's of the inside of the motor when I get it apart. It's been together for a good 4 years, so it should have signs of your potential problems I'd think by now,with over 200 passes on it I'd think. It's had breathers on it from day one.
When I take it apart, and it's clean as a whistle... what then?
As for engine life, manufacturing tolerances and by far superior lubrication, as well as better design's are why car's are going the distance that they are... it has very little to do with crankcase evap.. crankcase evap didn't come along to get anything out of the crankcase, it was developed to stop the fumes from the engine from going into the atmosphere.. it's a way of reducing total emmissions on a car. It came along, about the same time that cat. converters were required... you've been around long enough you should remember that.
I'll keep my breathers, and will get the vaccum pump on the motor while it's apart, and I will now make a point to take pic's of the inside of the motor when I get it apart. It's been together for a good 4 years, so it should have signs of your potential problems I'd think by now,with over 200 passes on it I'd think. It's had breathers on it from day one.
When I take it apart, and it's clean as a whistle... what then?
01-13-2010, 03:28 PM
#38
Reference links to further understand:
http://www.autoshop101.com/forms/h63.pdf
http://www.filtercouncil.org/techdata/tsbs/94-2R1.pdf
http://www.underhoodservice.com/Arti...CV_Servic.aspx
From "Bobistheoilguy":
Very! A clogged PCV valve will not only causes sludge, but the inability to vent those obnoxious gases such as moisture, condensation, blowby, etc. will accelerate the deterioration of your otherwise still lots of life left motor oil.
and if you choose to ignore it, your engine will start burning oil fairly soon due to oil control ring sticking(jammed) due to decomposed motor oil. Also: most seals, such as cam/crank esp. valve stem seals, the elastomers do not take deteriorated motor oil very well and will become brittle/hardened as the elastomer materials being attacked by these polluted motor oils. As a consequence: your engine will start to burn oil far sooner than expected.
And this:http://www.aa1car.com/library/pcv.htm
Positive Crankcase Ventilation (PCV)
Copyright AA1Car
.
The Positive Crankcase Ventilation (PCV) system reduces blowby emissions from the engine. About 20% of the total hydrocarbon (HC) emissions produced by a vehicle are blowby emissions from gases that get past the piston rings and enter the crankcase. The higher the mileage on the engine and the greater the wear on the piston rings and cylinders, the greater the blowby into the crankcase.
Before PCV was invented, blowby vapors were simply vented to the atmosphere through a "road draft tube" that ran from a vent hole in a valve cover or valley cover down toward the ground.
In 1961, the first PCV systems appeared on California cars. The PCV system used intake vacuum to siphon blowby vapors back into the intake manifold. This allowed the HC to be re-burned and eliminated blowby vapors as a source of pollution.
The system proved to be so effective that "open" PCV systems were added to most cars nationwide in 1963. An open PCV system draws air in through a mesh filter inside the oil filler cap or a breather on a valve cover. The flow of fresh air through the crankcase helped pull moisture out of the oil to extended oil life and reduce sludge. The only drawback to these early open PCV systems was that blowby vapors could still backup at high engine speed and loads, and escape into the atmosphere through the oil filler cap or valve cover breather.
In 1968, "closed" PCV systems were added to most cars. The breather inlet was relocated inside the air cleaner housing so if pressure backed up it would overflow into the air cleaner and be sucked down the carburetor. No vapors would escape into the atmosphere.
HOW PCV WORKS
The major component in the PCV system is the PCV valve, a simple spring-loaded valve with a sliding pintle inside. The pintle is tapered like a bullet so it will increase or decrease airflow depending on its position inside the valve housing. The movement of the pintle up and down changes the orifice opening to regulate the volume of air passing through the PCV valve.
The PCV valve is typically located in a valve cover or the intake valley, and usually fits into a rubber grommet. The location of the valve allows it to pull vapors from inside the engine without sucking oil from the crankcase (baffles inside the valve cover or valley cover deflect and help separate droplets of oil from the blowby vapors).
A hose connects the top of the PCV valve to a vacuum port on the throttle body, carburetor or intake manifold. This allows the vapors to be siphoned directly into the engine without gumming up the throttle body or carburetor.
Because the PCV system pulls air and blowby gases into the intake manifold, it has the same effect on the air/fuel mixture as a vacuum leak. This is compensated for by the calibration of the carburetor or fuel injection system. Consequently, the PCV system has no net effect on fuel economy, emissions or engine performance -- provided everything is working correctly.
WARNING: Removing or disconnecting the PCV system in an attempt to improve engine performance gains nothing, and is illegal. EPA rules prohibit tampering with any emission control device. Disabling or disconnecting the PCV system can also allow moisture to accumulate in the crankcase, which will reduce oil life and promote the formation of engine-damaging sludge.
HOW PCV FLOW CHANGES WITH ENGINE SPEED & LOAD
The flow rate of a PCV valve is calibrated for a specific engine application. For the system to function normally, therefore, the PCV valve must adjust the flow rate as operating conditions change.
When the engine is off, the spring inside the valve pushes the pintle shut to seal the crankcase and prevent the escape of any residual vapors into the atmosphere.
When the engine starts, vacuum in the intake manifold pulls on the pintle and sucks the PCV valve open. The pintle is pulled up against the spring and moves to its highest position. But the tapered shape of the pintle does not allow maximum flow in this position. Instead, it restricts flow so the engine will idle smoothly.
The same thing happens during deceleration when intake vacuum is high. The pintle is pulled all the way up to reduce flow and minimize the effect of blowby on decel emissions.
When the engine is cruising under light load and at part throttle, there is less intake vacuum and less pull on the pintle. This allows the pintle to slide down to a mid-range position and allow more airflow.
Under high load or hard acceleration conditions, intake vacuum drops even more, allowing the spring inside the PCV valve to push the pintle valve even lower to its maximum flow position. If blowby pressure builds up faster than the PCV system can handle it, the excess pressure flows back through the breather hose to the air cleaner and is sucked back into the engine and burned.
In the event of an engine backfire, the sudden rise in pressure inside the intake manifold blows back through the PCV hose and slams the pintle shut. This prevents the flame from traveling back through PCV valve and possibly igniting fuel vapors inside the crankcase.
PCV MAINTENANCE
Because the PCV system is relatively simple and requires minimal maintenance, it is often overlooked. The common replacement interval for many PCV valves is 50,000 miles, yet many engines have never had the PCV valve replaced. Many late model owners' manuals do not even have a recommended replacement interval listed for the PCV valve. The manual may only suggest "inspecting" the system periodically.
On many 2002 and newer vehicles with OBD II, the OBD II system monitors the PCV system and checks the flow rate once during each drive cycle. But on older OBD II and OBD I systems, the PCV system is NOT monitored. So a problem with the PCV system on a pre-2002 vehicle probably won't turn on the MIL (malfunction indicator lamp) or set a diagnostic trouble code (DTC).
PCV valves can last a long time, but they may eventually wear out or clog -- especially if the vehicle owner neglects regular oil changes, and sludge builds up in the crankcase. The same sludge and oil varnish that gums up the engine can also plug up the PCV valve.
http://www.autoshop101.com/forms/h63.pdf
http://www.filtercouncil.org/techdata/tsbs/94-2R1.pdf
http://www.underhoodservice.com/Arti...CV_Servic.aspx
From "Bobistheoilguy":
Very! A clogged PCV valve will not only causes sludge, but the inability to vent those obnoxious gases such as moisture, condensation, blowby, etc. will accelerate the deterioration of your otherwise still lots of life left motor oil.
and if you choose to ignore it, your engine will start burning oil fairly soon due to oil control ring sticking(jammed) due to decomposed motor oil. Also: most seals, such as cam/crank esp. valve stem seals, the elastomers do not take deteriorated motor oil very well and will become brittle/hardened as the elastomer materials being attacked by these polluted motor oils. As a consequence: your engine will start to burn oil far sooner than expected.
And this:http://www.aa1car.com/library/pcv.htm
Positive Crankcase Ventilation (PCV)
Copyright AA1Car
.
The Positive Crankcase Ventilation (PCV) system reduces blowby emissions from the engine. About 20% of the total hydrocarbon (HC) emissions produced by a vehicle are blowby emissions from gases that get past the piston rings and enter the crankcase. The higher the mileage on the engine and the greater the wear on the piston rings and cylinders, the greater the blowby into the crankcase.
Before PCV was invented, blowby vapors were simply vented to the atmosphere through a "road draft tube" that ran from a vent hole in a valve cover or valley cover down toward the ground.
In 1961, the first PCV systems appeared on California cars. The PCV system used intake vacuum to siphon blowby vapors back into the intake manifold. This allowed the HC to be re-burned and eliminated blowby vapors as a source of pollution.
The system proved to be so effective that "open" PCV systems were added to most cars nationwide in 1963. An open PCV system draws air in through a mesh filter inside the oil filler cap or a breather on a valve cover. The flow of fresh air through the crankcase helped pull moisture out of the oil to extended oil life and reduce sludge. The only drawback to these early open PCV systems was that blowby vapors could still backup at high engine speed and loads, and escape into the atmosphere through the oil filler cap or valve cover breather.
In 1968, "closed" PCV systems were added to most cars. The breather inlet was relocated inside the air cleaner housing so if pressure backed up it would overflow into the air cleaner and be sucked down the carburetor. No vapors would escape into the atmosphere.
HOW PCV WORKS
The major component in the PCV system is the PCV valve, a simple spring-loaded valve with a sliding pintle inside. The pintle is tapered like a bullet so it will increase or decrease airflow depending on its position inside the valve housing. The movement of the pintle up and down changes the orifice opening to regulate the volume of air passing through the PCV valve.
The PCV valve is typically located in a valve cover or the intake valley, and usually fits into a rubber grommet. The location of the valve allows it to pull vapors from inside the engine without sucking oil from the crankcase (baffles inside the valve cover or valley cover deflect and help separate droplets of oil from the blowby vapors).
A hose connects the top of the PCV valve to a vacuum port on the throttle body, carburetor or intake manifold. This allows the vapors to be siphoned directly into the engine without gumming up the throttle body or carburetor.
Because the PCV system pulls air and blowby gases into the intake manifold, it has the same effect on the air/fuel mixture as a vacuum leak. This is compensated for by the calibration of the carburetor or fuel injection system. Consequently, the PCV system has no net effect on fuel economy, emissions or engine performance -- provided everything is working correctly.
WARNING: Removing or disconnecting the PCV system in an attempt to improve engine performance gains nothing, and is illegal. EPA rules prohibit tampering with any emission control device. Disabling or disconnecting the PCV system can also allow moisture to accumulate in the crankcase, which will reduce oil life and promote the formation of engine-damaging sludge.
HOW PCV FLOW CHANGES WITH ENGINE SPEED & LOAD
The flow rate of a PCV valve is calibrated for a specific engine application. For the system to function normally, therefore, the PCV valve must adjust the flow rate as operating conditions change.
When the engine is off, the spring inside the valve pushes the pintle shut to seal the crankcase and prevent the escape of any residual vapors into the atmosphere.
When the engine starts, vacuum in the intake manifold pulls on the pintle and sucks the PCV valve open. The pintle is pulled up against the spring and moves to its highest position. But the tapered shape of the pintle does not allow maximum flow in this position. Instead, it restricts flow so the engine will idle smoothly.
The same thing happens during deceleration when intake vacuum is high. The pintle is pulled all the way up to reduce flow and minimize the effect of blowby on decel emissions.
When the engine is cruising under light load and at part throttle, there is less intake vacuum and less pull on the pintle. This allows the pintle to slide down to a mid-range position and allow more airflow.
Under high load or hard acceleration conditions, intake vacuum drops even more, allowing the spring inside the PCV valve to push the pintle valve even lower to its maximum flow position. If blowby pressure builds up faster than the PCV system can handle it, the excess pressure flows back through the breather hose to the air cleaner and is sucked back into the engine and burned.
In the event of an engine backfire, the sudden rise in pressure inside the intake manifold blows back through the PCV hose and slams the pintle shut. This prevents the flame from traveling back through PCV valve and possibly igniting fuel vapors inside the crankcase.
PCV MAINTENANCE
Because the PCV system is relatively simple and requires minimal maintenance, it is often overlooked. The common replacement interval for many PCV valves is 50,000 miles, yet many engines have never had the PCV valve replaced. Many late model owners' manuals do not even have a recommended replacement interval listed for the PCV valve. The manual may only suggest "inspecting" the system periodically.
On many 2002 and newer vehicles with OBD II, the OBD II system monitors the PCV system and checks the flow rate once during each drive cycle. But on older OBD II and OBD I systems, the PCV system is NOT monitored. So a problem with the PCV system on a pre-2002 vehicle probably won't turn on the MIL (malfunction indicator lamp) or set a diagnostic trouble code (DTC).
PCV valves can last a long time, but they may eventually wear out or clog -- especially if the vehicle owner neglects regular oil changes, and sludge builds up in the crankcase. The same sludge and oil varnish that gums up the engine can also plug up the PCV valve.
01-13-2010, 03:34 PM
#39
That's all fine and well.. but at what point do you think oil starts to deteriorate to the point that it's going to cause any of those issues? Do you think, that if oil is changed after every 3000 miles it will occur? After running as many oil analysis as I have over the years... I've found that non synthetic motor oil is generally good for about 5500 to 6500 miles before it's actually lost it's ability to do it's job.
So... if you're changing it every 3000 miles and are taking it out of the engine while it's up to temp... how much of that is actually an issue?
As for the epa regulations and whatnot, as soon as you put headers on the car you're screwed in that department anyway, so the PCV is the last thing you need to worry about.
So... if you're changing it every 3000 miles and are taking it out of the engine while it's up to temp... how much of that is actually an issue?
As for the epa regulations and whatnot, as soon as you put headers on the car you're screwed in that department anyway, so the PCV is the last thing you need to worry about.
01-13-2010, 03:37 PM
#40
Honestly 200 passes isnt much run time man. Especially if your running in the 10's. Lets just do the math on that, 200 passes at 1/4 mile per pass = 50 total miles. Now of coarse thats not including what little driving goes into getting loaded, pit driving & what not. But you see my point, your not gonna see the build up a typical street car sees. Granted your harder on your engine running that hard that many passes put total time driving is FAR less than a non- race car.
Since I work as a draftsman in the oil/gas industry designing filters, coalescers & separators I can see how a properly designed catch can could actually be the end all of oil in the intake. With a properly designed interior the heavy oil particles which would normally flow on thru get trapped on the interior walls & other internals causing them to pool in the bottom.
Granted, like stated above some cans are nothing more than a empty shell with 2 fittings on them though. And those cans are far from designed well. But the one TLewis listed all have some type of internal separator. I think the main deal here is trapping the oil mist. And sucking the gasses out at the same time is just a extra positive you get.
Since I work as a draftsman in the oil/gas industry designing filters, coalescers & separators I can see how a properly designed catch can could actually be the end all of oil in the intake. With a properly designed interior the heavy oil particles which would normally flow on thru get trapped on the interior walls & other internals causing them to pool in the bottom.
Granted, like stated above some cans are nothing more than a empty shell with 2 fittings on them though. And those cans are far from designed well. But the one TLewis listed all have some type of internal separator. I think the main deal here is trapping the oil mist. And sucking the gasses out at the same time is just a extra positive you get.