Instead of catch can, why not delete PCV?

[Doug_Scott]

On 8/15/2019 at 12:29 PM, SquireSCA said:

What I wish there was, was a way to route the crankcase vent to the exhaust manifold... Let that draw the oily air via vacuum and have it bypass the motor entirely...

You can do that on bikes, which normally dump the crankcase vent into the airbox...  they also have a hose off the airbox that goes into the exhaust manifold to help "clean up emissions"...  So you plug the airbox, and route that hose to the exhaust(normally called SAI or PAIR, depending on the make of bike) and connect the crackcase vent to that, and it will pull a slight vacuum on the crankcase...

Forgive me is someone already explained the line from the air box to the exhaust on the motorcycles.  Chrysler started that way back in the 70s.  Pretty sure it was called something like aspirator line, anyways, when you took the air cleaner lid off it made this loud rattle like noise.  To stop it, if the car was just going to be idling, a 1in x 1in piece of paper over the open line would shut it up.  There was vacuum on that port from the rear of the passenger side exhaust manifold.  Motorcycles have them to, they are to draw in filtered air into the exhaust in order to help burn the fuel in the exhaust manifold.  Does a good job.  

The purpose of the PCV valve is to help the engine crankcase handle the moisture that accumulates in the crankcase.  A guy I know had a Mercedes ML320.  He had a supercharger on it, and the guy that did it screwed around with the pcv system because the instructions did not deal with it.  The supercharger was based on a procharger.  In the spring, summer, fall it worked great.  In the winter is when the issues appeared.  He drove short city trips and parked in his underground parking lot.  One day he went to a friends day for the day, and around midnight he went out and started his Mercedes and proceeded to drive home.  About half way home his oil light came on.  He shut the engine down, and called someone to come get him.  While waiting he opened the hood and checked the oil.  Dip stick said none.  He called his friend to bring him some oil, he knew it took a lot of oil, couldn't remember how much so he asked his friend to get a case of 24litres, what he didn't use would not go bad, he will use it.  By the time his friend arrived, the outside temp was something like -30C that night.  He filled the truck with oil, I cannot recall how many he put into it, but it near the max capacity.  He drove the Mercedes somewhere between 8 and 10 miles, with the light on.  What had happened was that since the PCV system was inoperative, tremendous amounts of water condensation, that tan coloured slimey crap that is water and oil were trying for all they were worth to become a solution instead of just a mixture, had covered every surface inside that engine, and had frozen.  That meant that because by design Mercedes run their crankcase under a positive pressure normally, and when the PCV system is working it handles it, but in this case, that positive pressure had to escape somewhere, and Mercedes in their brilliant design ran their dipstick tube right down to the bottom of the oil pan, that positive pressure first pushed the dipstick out of the tube until it came out far enough that the oil was pushed out of that engine in a 3/8(more correctly 10mm) diameter stream until the pan was essentially empty.  By the time his friend had arrived, the engine's heat had managed to uncover an opening in the valve cover allowing the pressure to vent.  But it had a rather ominous sound coming from it.  I don't recall what it cost him.  He had a supercharger kit for sale though.

If you are intending on bypassing, disabling, or doing anything to alter its job, PCV first came on California cars sometime in the early 60s I think.  Prior to that they used a "road draft" tube.  To this day everyone knows the middle of your lane is very slippery when it first starts to rain.  Today its nothing compare to how it used to be when cars had a tube with a slash cut on the end to put that oily mess all over the middle of their lane.  We don't need to go back to those days.

Pretty sure I heard that the 2020 Vette will have a can on it from the factory.

[SquireSCA]

So an update...  Put around 450 miles or so on the truck, give or take.  Pulled the can today to see how much oil was in there, and there was roughly at least half, if not 3/4 of an inch of motor oil in the can... I left it in, and will pour it out and measure it at the 1,000 mile mark.

I also picked up a can of the Seafoam intake cleaner that I plan to do soon, now that I am trapping at least most of the oil from going into the intake...  I would imagine at this rate, by the time I hit 1,000 miles I will have a couple inches of oil in the can...

[Doug_Scott]

Mine goes over 8000km between oil changes using oil life monitor and I get under 5cm in a medium Tim Hortons coffee cup.  it takes 18 months or so to go that far.  I use the truck twice a month, with each day going 200km.  It is not uncommon for the truck to sit close to 3 weeks between trips.  The trips are long enough to get everything hot, with zero moisture in crankcase.  I never understood the time between oil changes, Its not like the oil is doing anything =, it is just sitting there.  Short trips is a different matter.

[SquireSCA]

I do my oil changes every 5k miles, but the dealer does them so I don't know how low it is... I should probably check from time to time, LOL

[davester]

41 minutes ago, SquireSCA said:

So an update...  Put around 450 miles or so on the truck, give or take.  Pulled the can today to see how much oil was in there, and there was roughly at least half, if not 3/4 of an inch of motor oil in the can... I left it in, and will pour it out and measure it at the 1,000 mile mark.

I also picked up a can of the Seafoam intake cleaner that I plan to do soon, now that I am trapping at least most of the oil from going into the intake...  I would imagine at this rate, by the time I hit 1,000 miles I will have a couple inches of oil in the can...

Depending on the design of the intake manifold, there can be a fair amount of oil that has already collected in it.  When I did the knock sensors/intake manifold gaskets for my 6.0L LQ4, a bunch of oil spilled out of the intake manifold when I took it off.  It was basically filled up to the level of the intake ports with oil...

[SquireSCA]

48 minutes ago, davester said:

Depending on the design of the intake manifold, there can be a fair amount of oil that has already collected in it.  When I did the knock sensors/intake manifold gaskets for my 6.0L LQ4, a bunch of oil spilled out of the intake manifold when I took it off.  It was basically filled up to the level of the intake ports with oil...

So you think I should pop the cover and look in there, and soak up the oil with some paper towels or something?

[davester]

25 minutes ago, SquireSCA said:

So you think I should pop the cover and look in there, and soak up the oil with some paper towels or something?

Sorry, I don't know the design of your intake manifold.

 

Mine is molded plastic, and I had to tilt it in a number of different ways to get oil of out the runners, as they aren't just straight tubes to each port.  There was no chance of getting much of that oil out just via the opening where the throttle plate mounts to.

 

If I do get/install a catch can, I'd also take off my intake manifold and drain/clean it as best I can again.

 

My original comment was aimed more at your use of spraying in seafoam intake cleaner, as if your intake manifold is similar to mine, it would do virtually nothing to get any of that oil out.

[Doublebase]

2 hours ago, davester said:

Sorry, I don't know the design of your intake manifold.

 

Mine is molded plastic, and I had to tilt it in a number of different ways to get oil of out the runners, as they aren't just straight tubes to each port.  There was no chance of getting much of that oil out just via the opening where the throttle plate mounts to.

 

If I do get/install a catch can, I'd also take off my intake manifold and drain/clean it as best I can again.

 

My original comment was aimed more at your use of spraying in seafoam intake cleaner, as if your intake manifold is similar to mine, it would do virtually nothing to get any of that oil out.

I would think that most of the oil you saw in your intake was relatively fresh and often replenished whenever you used your car. When the engine is running there is a lot of vacuum and turbulence inside that manifold, wet oil should be sucked into the cylinders and burned. 

 

A product like Seafoam or CRC intake cleaner, is not designed to clean oil out of a manifold, but rather carbon deposits left by the oil and byproducts of combustion...and in all honesty I don't think it's even doing much of that (if anything at all). Carbon deposits and varnish need continuous application of a solvent to remove deposits. A one time application every 5,000-10,000 miles is not going to do much of anything. But yet I still do it...probably because I like to fool myself that it's doing something (it makes me feel good, lol). In all honesty, some carbon deposits are very hard to remove and require much more than a solvent - usually carbon needs to be sand blasted or scraped off of a surface - the only cleaner I've seen remove carbon is the types used in dunk tanks, and it's very caustic. You place the part into an agitator filled with a corrosive cleaner, close the lid and let the machine agitate the fluid/part for 30-40 minutes. Nasty stuff. 

[davester]

9 hours ago, Doublebase said:

I would think that most of the oil you saw in your intake was relatively fresh and often replenished whenever you used your car. When the engine is running there is a lot of vacuum and turbulence inside that manifold, wet oil should be sucked into the cylinders and burned. 

 

A product like Seafoam or CRC intake cleaner, is not designed to clean oil out of a manifold, but rather carbon deposits left by the oil and byproducts of combustion...and in all honesty I don't think it's even doing much of that (if anything at all). Carbon deposits and varnish need continuous application of a solvent to remove deposits. A one time application every 5,000-10,000 miles is not going to do much of anything. But yet I still do it...probably because I like to fool myself that it's doing something (it makes me feel good, lol). In all honesty, some carbon deposits are very hard to remove and require much more than a solvent - usually carbon needs to be sand blasted or scraped off of a surface - the only cleaner I've seen remove carbon is the types used in dunk tanks, and it's very caustic. You place the part into an agitator filled with a corrosive cleaner, close the lid and let the machine agitate the fluid/part for 30-40 minutes. Nasty stuff. 

I doubt there's enough airflow to do that, as the oil is pretty heavy.

 

My intake manifold seemed to be filled to just below the level of the intake ports, not just a little at the bottom of the manifold.  I think it would only burn the oil that splashed into the intake ports or ran into them from the truck tilting.  I think it would be unlikely that oil would go away if I put in a catch can, it would just go down to a level where no more would splash or run into the intake manifolds anymore.

[Doublebase]

44 minutes ago, davester said:

I doubt there's enough airflow to do that, as the oil is pretty heavy.

 

My intake manifold seemed to be filled to just below the level of the intake ports, not just a little at the bottom of the manifold.  I think it would only burn the oil that splashed into the intake ports or ran into them from the truck tilting.  I think it would be unlikely that oil would go away if I put in a catch can, it would just go down to a level where no more would splash or run into the intake manifolds anymore.

The manifold is basically a vacuum cleaner, having said that, perhaps the grooves the oil was stuck in were deep enough to not be touched by the vacuum or turbulence of in rushing air? But you have 8 cylinders going down on the intake stroke creating vacuum, drawing in air from those runners. I mean when that throttle plate snaps shut, there's a pretty strong pull in that manifold going on...but then again you may be right if there was that much oil in there just pooling around.

[SquireSCA]

Yeah, I have no illusions that the Seafoam will magically pull any old oil out of the manifold... but I figure it can't hurt, and if it removes some of the buildup already on the valves, then the catch can can keep it, or at least slow down the process of it accumulating more...

[Doublebase]

4 hours ago, SquireSCA said:

Yeah, I have no illusions that the Seafoam will magically pull any old oil out of the manifold... but I figure it can't hurt, and if it removes some of the buildup already on the valves, then the catch can can keep it, or at least slow down the process of it accumulating more...

Yeah I use the seafoam or CRC and run it right through the catch can hose, don't know if it helps, kind of doubt it...but I always say when regarding truck maintenance...if it makes you feel good, do it. Plain and simple. There's a certain satisfaction in thinking that what you are doing is helping and I think that is important in long term car ownership...it keeps you going, it's pride of ownership. And sometimes it really does help in the long run.

[Doug_Scott]

8 hours ago, Doublebase said:

The manifold is basically a vacuum cleaner, having said that, perhaps the grooves the oil was stuck in were deep enough to not be touched by the vacuum or turbulence of in rushing air? But you have 8 cylinders going down on the intake stroke creating vacuum, drawing in air from those runners. I mean when that throttle plate snaps shut, there's a pretty strong pull in that manifold going on...but then again you may be right if there was that much oil in there just pooling around.

In order for a vacuum cleaner to work it requires flow.  Once you snap the throttle shut(you cant actually snap the throttle shut, drive by wire prevents the throttle blades from snapping shut, they float shut)there is insufficient flow to pull the oil up from where it is.  Oil misting is heavier than fuel and air misting, and any oil mist in the fuel/air mist will try to go straight on sharp turns and over time it will pool in pockets in the intake manifold.  You can see this work by removing any steel wool or whatever you have in the catch can, dry up any oil in there, and then run it for 1000km.  Then take a look inside the can.  It will have oil in there, simply due to oil being heavier than whatever carried it in there.   

[SquireSCA]

Here it is after 900 miles.  A couple ounces of dirty oil.  Oil change itself was only 5k miles ago, it's going in on Monday for an oil change and the brake recall...  

 

[JCunningham]

you guys have a lot of oil loss . i have a 17 Camaro LT1  and had a 12 Camaro LS3 both have elite catch cans. at 8000-10000 miles the can wouldn't be half full and id only lose maybe half qt.  intake still has oil in it even though the can was put on befor my cleaned and ported intake.