How to Stop Oil Mist From Valve Covers

[MikeStang 247]

Okay guys now that I have some miles on my car I am starting to see all the little issues and problems and its time to start the tuning / Tweaking process.

 

I seem to be having some oil coming from the valve cover fill hole.

Motor is a 408, compression 9.8-1 AFR heads etc. Motor runs great with no smoking

 

I have baffled valve covers with a PCV Valve in the pass side valve cover Which is connected to the PCV Connection port on my Holley Carb as its supposed to be, and on the driver side valve cover I have a standard push in breather.

 

I began to notice oil residue on the valve cover on the driver side after the drive from BR to Cruising the coast last weekend, but didnt worry about it because it wasn't that bad.

After CTC we drove the car home and I drove it every day this week and on Tuesday when I killed it I noticed a little smoke from under the hood....Upon inspection I saw that the breather cap filter media was saturated with oil and a few drops had leaked out, so I installed another push in breather that is just like one of the K&N push in units so you can see all the filter media and this morning before I drove it to work I looked at it after driving about 200 miles yesterday.

the filter media was not completely saturated but it was nice and golden oil colored but not dripping yet.

At idle with the breather out there is No smoke or blow by and when you rev the motor up you don't get any smoke or blow by.

I also pulled the PCV hose and valve and there is NO oil in the hose or valve or base plate of the carb, and the PCV valve has good Vac. when you pull it with the motor running, but it doesn't effect the way the car runs when its pulled.

The engine runs too well and doesnt smoke or foul plugs so I doubt its an engine problem but WTF?

 

 

So all that being said what should I do to control this crap?

and why is it happening?

Should I run 2 PCV valves or some type of catch can?

[Max Power 74]

Running 2 PCV valves is not how the system works. The valve is just a regulator for air flow. You don't need two. It supposed to be a circular system, the breather on the drivers side is the intake, not a vent, and the PCV on the passenger side is in essence the exhaust of your crankcase, being pulled back into the intake, regulated by vacuum through the valve. Here is a quick primer:

http://auto.howstuffworks.com/positive-crankcase-ventilation-system.htm

 

The intake vent, or breather, will get oil vapor in situations where it is no longer acting as an intake. This usually happens when the pressure in the crankcase overcomes the vacuum's ability to pull air in. This might be because of a faulty PCV valve, too much blowby due to age or wear, or very high revs where vacuum drops significantly.

 

Reading your description, you are saying you are not seeing vapor when it idles, nor when you rev it, so I am not sure how the crankcase is generating more pressure than the intake is creating vacuum. It kinda doesn't make sense. Maybe an intermittently faulty PCV?

 

If it continues, and the venting of the crankcase continues to exit through the breather intake, you can fabricate a catch and drainback type of system at the breather. I did it on an old engine using a gas filter mounted to the top of a sealed breather, forcing the oily air through the gas filter separated the oil from the air, and the oil drained back into the engine. Unfortunately, the solution was just as ugly as oil residue on the valve covers.

[barnett468 418]

hello;

 

your pcv valve may be too small. pinch off the rubber hose with the pcv connected to the valve cover. the rpm should drop slightly, up to around 100 rpm. if it does not change, the valve because it is either bad or it is too small.

 

if you pull it out with the engine running and put your finger over it and it has very little to no suction it is bad so a new one the same size you have, may or may not work, just have to try it.

 

if you leave it as is, you should connect a breather hose from a vented oil fill cap to the air cleaner.

 

you may have a little blow by.

.

Edited October 17, 2014 by barnett468

[MikeStang 247]

Well Nothing has changed on the motor since we dynoed it other than being installed in my car lol...I was running 2 breathers and No PCV valve when we dynoed it and decided once I installed it to go ahead and add a PCV valve and do it right.

Thus I popped in a valve and left one push on breather for air to be drawn in.

I know how the PCV system works for sure.

The car has more power than the suspension can handle at this point so im about 99% sure there is no damage or what would be considered excessive blow by, altho I know all motors have some blow by.

I made sure when I built the motor that I bought baffeled valve covers because we have been fighting Oil in the PCV system in a friends car for ever and when we installed baffels it fixed his problem.

I have a feeling that at higher RPM's and spirited driving that the Crank case is building up more pressure than there is Vac to overcome it.

I have pinched off the hose and there is no change so maybe the valve is just too small.

Got a Part number for a larger valve you would recommend?

Adding anything to the air cleaner will be tough since Im having to run a short filter to close the hood with the Vic Junior intake lol and I still get a bit of rubbing on the under side of the hood, and I really DON'T wasnt to run a catch can.

I wonder if I modified a set of valve covers like the older ones on the mustangs from the 90s had would work.

I know yall remember them, the cover had a filler neck about 2" tall with a screw on cap and a hose bung welded on the side of the filler neck that had a hose going to the air cleaner,.

I would make it like that but put a push in breather on it and run the tube back to a secondary hole in the valve cover...Maybe put a baffel of sorts in the filler neck so it directed air flow towards the tube in the side to help funnel the oil that direction at higher RPM's?

 

Really want to try the valve tho...someone give me a few part numbers or a year, make and model for something with a bigger PCV Valve

[LoneWolf2U 136]

Simple test for pcv system, while engine is running remove breather cap and place a plain piece of paper over breather hole. It should hold it in place thru idle to 3k plus rpms. If not the valve is not allowing enough vac on the engine to remove crankcase pressures. switch to larger flow valve, Poss big block valve may work for your set up.

[barnett468 418]

Ok, first of all your valve is definitely too small. all engines have some blow by. the bigger the engine the bigger the pcv typically needs to be, UNFORTUNATELY, there is no such thing as a pcv valve flow chart any longer. There used to be an AC Delco pcv flow tester but it is 40 years old. Sooooo, you can try ones from a 70 - 73 Hemi, a 70 LS6 Chevelle or 70 435 hp Vette, OR, you can buy the fancy shiny aluminum one below and not worry if yours is big enough.

 

http://mewagner.com/?page_id=444

 

 

Also, unless you buy an orig off of ebay, the one you get from the parts store is most likely NOT going to be the correct one for the cars I mentioned and will most likey be a lower flow type.

 

.

Edited October 17, 2014 by barnett468

[MikeStang 247]

Now that is a cool little valve right there but they are damn proud of it.

Ill see about getting a valve for a larger motor and give that a shot.

The Vac on my hose is hella strong but there is no idle change when removed...I remember when I removed it i thought it was odd that there was no idle up or down.

maybe i should install a larger hose as well...think I'm running a 3/8" right now so maybe step up to 1/2".

Wondering if I should swap the valve covers around as well and have the PCV valve in the front half of the valve cover but still on the pass side....I read somewhere that is the best place to suck from.

[MikeStang 247]

Looking through more info it would seem that I might want a PCV valve from like an old Ford Pinto or something that required less vac to keep it open.

Now since they required less vac to work wouldn't it stand to reason that as my motor revs higher it makes less vac thus would require a lighter PCV valve to stay open to continue the draw of air through the system there by stopping the oil mist at higher RPM's?

[barnett468 418]

hello

 

 

can you feel your valve suck very much if you put your finger over it?

 

yes, that is a very cool valve. it is designed for big engines and/or any engine with excessive blow by etc..

 

the pcv should go to the csrb or carb spacer and never directly to the intake manifold.

 

no, a 3/8 hose is enough. if you need a 1/2" hose, you need new rings, lol.

 

here's how to see exactly what is going on and how to set that nice new valve you will eventually buy.

 

To set the valve for cruise you can get a twist in rubber grommet, a threaded brass fitting with a 1/8" or 1/4” npt threaded hole in the end, a threaded fitting with a 1/8 - 3/16 nipple on it, then screw that into the big fitting and jam it into the grommet. Put a little grease around the outside to seal it at least when it gets to the point of having vacuum.

 

Connect a pressure or vacuum gauge to it.

Drive the car on a flat road at around 40 mph.

Set valve so that there is around 5hg of vacuum reading on the gauge at that speed.

Try it at 50 and 60 also.

As long as there is never pressure at steady cruise it is very close.

 

keep in mind, the ones the parts store gives you will likely not be correct and a used orig for any of the cars i mentioned will likely hurt your wallet pretty bad.

.

Edited October 17, 2014 by barnett468

[barnett468 418]

Looking through more info it would seem that I might want a PCV valve from like an old Ford Pinto or something that required less vac to keep it open.

Now since they required less vac to work wouldn't it stand to reason that as my motor revs higher it makes less vac thus would require a lighter PCV valve to stay open to continue the draw of air through the system there by stopping the oil mist at higher RPM's?

No.

 

A pcv for a 140 ci 90 hp engine that that revs to 4600 rpm on a downhill with a tailwind OR...a valve for a fire breathing 500 hp 1970 Boss 429 that revs to 6800?

.

Edited October 17, 2014 by barnett468

[Max Power 74]

That adjustable valve is pretty slick. Did not know they made those.

 

Here is a listing for a higher flow valve than stock:

http://stores.hi-potek.com/high-flow-pcv-valve-performance-camshaft-with-lower-vacuum-signal/

 

http://www.dakotart.com/forum/showthread.php?t=21992

[MikeStang 247]

Barnett, when I stick my finger over my valve it has a very strong pull on the ole finger and i have about 11.5hg vac at idle but need to try it in gear, cant think it will drop lower than 10hg tho because my power brakes work perfectly.

so I need something with a heavier spring then?

I know the little cone plunger is pulled full open when the car is idling which is in essence closing the valve correct?

and a heavier spring would make it harder to open so it would not be allowing as much metering at idle when I didnt need it..

Then when your at WOT and Vac is what ever it is it wont pull the cone closed but will be open the correct amount to allow evac to happen?

Am i understanding this right?

Ill wipe oil off my valve covers from now on before Ill spend that on a PCV valve LOL

[MikeStang 247]

Looks like your trying to get a valve that doesnt have such a weak spring that your idle vac pulls the cone all the way up and almost closed but at the same time has to be strong enough to maintain that center point between flow and Vac to make evac possible

[barnett468 418]

That adjustable valve is pretty slick. Did not know they made those.

 

 

Yeah ,its been around for a little while but as you know, most people don’t pay much attention to the pcv and even if they do they don’t realize there are different sizes etc.. Therefore no one looks for them. The adjustable one is the best overall option because you can set it to exactly where it should be. I have seen the ones in the link you posted but never used them. They may work or may even have too much flow at idle which will be bad. It's obviously a trial and error thing, but if it doesn't work, its $18.00 down the drain and back to more trial and error and oil all over the engine.

[j69302 11]

Your breather on the driver side should be tied into the air filter housing. Either through a grommet, fitting and hose, or directly to the stock air filter housing if you have one.

 

At full power and low vacuum conditions, the PCV isnt going to do much, thus anything excess will come out the oil filler breather.

 

Having the oil filler breather hooked to the air filter assembly will create a vacuum source to purge the crank case under low manifold vacuum/full throttle situations.

 

Mine does the same thing, I made it a closed system like it is supposed to be, instead of open, and problem solved.

[barnett468 418]

Barnett, when I stick my finger over my valve it has a very strong pull on the ole finger and i have about 11.5hg vac at idle but need to try it in gear, cant think it will drop lower than 10hg tho because my power brakes work perfectly.

so I need something with a heavier spring then?

I know the little cone plunger is pulled full open when the car is idling which is in essence closing the valve correct?

and a heavier spring would make it harder to open so it would not be allowing as much metering at idle when I didnt need it..

Then when your at WOT and Vac is what ever it is it wont pull the cone closed but will be open the correct amount to allow evac to happen?

Am i understanding this right?

Ill wipe oil off my valve covers from now on before Ill spend that on a PCV valve LOL

 

the valve function is a bit complicated actually but the bottom line is that it is not flowing enough air when it needs to. if you simply remove the hose and plug it into the valve civer, it should be flowing enough air and even too much air. it is possible that if you removed the valve that the orifice in that particular pcv would be too small.

 

look at it this way. that shiny new adjustable one will only cost you the equivalent of two full tanks of gas, or 3 cases of Heineken or...

[MikeStang 247]

So its a combination of Orifice diameter and spring pressure combined then ?

There is no way for me to connect my breather to my air cleaner unless I midify my air cleaner and I really donw want a hose running to the air cleaner anyhow...

Wondering if i maybe add a tube on top of the valve cover to help get it up and away from the oil

[barnett468 418]

So its a combination of Orifice diameter and spring pressure combined then ?

There is no way for me to connect my breather to my air cleaner unless I midify my air cleaner and I really donw want a hose running to the air cleaner anyhow...

Wondering if i maybe add a tube on top of the valve cover to help get it up and away from the oil

 

yes.

 

the filter will still get oily up higher but it will take a little longer.

[MikeStang 247]

Well last night after I installed my spacers behind the new rims and tires I took it for a ride and decided it was all good so I did a few short burn outs to warm the tires up and see if I could get any traction...Well the answer was yes I could get traction until I hit the secondaries hahah.

Anyhow while doing my last little hole shot car started smoking so I took it home and raised the hood and to my surprise it had sprayed the pass side engine compartment with oil, the dipstick tube was pushed out 1/2 an inch and the valve cover was leaking its ass off.

Seems the PCV valve that I installed that I thought was BIGGER was worse off than the one that I had in the car to begin with.

And to top it all off its leaking transmission fluid from SOMEWHERE no as well GRRRRR

[Max Power 74]

If you are pushing dipstick tubes out, I am not sure the PCV valve is your biggest problem.

[1969_Mach1 333]

If it were mine I would perform a cylinder leakage test to verify the ring sealing condition. It sounds like you drive the car fairly hard. I have no personal experience with a 408 or even a 393, but obviously the longer piston travel is going to wear rings faster than shorter stroke motors. If the leakage test is okay, then proceed to solve the high crankcase pressure issue.

[MikeStang 247]

Motor have MAYBE 1500 miles on it...Its a fresh build and was Dynoed.

Burns no oil, doesnt smoke and has more power than I know what to do with so like I have said I dont think there is anything wrong with the motor but I will do a leak down test today.

We dynoed the motor with breathers on the valve covers and had over 20 pulls on it and it never leaked a drop of oil...I put it in the car and installed a PCV system and immediatley the front seal started leaking as well as the valve covers etc...

[barnett468 418]

Well last night after I installed my spacers behind the new rims and tires I took it for a ride and decided it was all good so I did a few short burn outs to warm the tires up and see if I could get any traction...Well the answer was yes I could get traction until I hit the secondaries hahah.

Anyhow while doing my last little hole shot car started smoking so I took it home and raised the hood and to my surprise it had sprayed the pass side engine compartment with oil, the dipstick tube was pushed out 1/2 an inch and the valve cover was leaking its ass off.

Seems the PCV valve that I installed that I thought was BIGGER was worse off than the one that I had in the car to begin with.

And to top it all off its leaking transmission fluid from SOMEWHERE no as well GRRRRR

 

1. its impossible for the dip stick tube to move if it is PROPERLY installed because it is bolted to the block.

 

i guess that 100.00 pcv i posted for you looks better right about now, however, you have so much blow buy that you might need 8 of them.

.

[rwcstang 201]

damn, I had a similar situation as you but the valve seals wasn't seating correctly. luckily it was an easy fix. Hopefully it will be the same with yours. GL

[MikeStang 247]

LOL... It didnt push the TUBE out it pushed the dipstick out of the tube LOL .... MY bad....