Just got my 352 fired up in my 66 Ford F100 that me and my step son have been building. So the original setup was passengers side valve cover was a PVC valve, and the drivers side was a filler cap. Due to an engine fire we replaced the valve covers, I stuck with the PVC but instead of a oil fill cap I installed a oil breather, any issues with doing this? The truck runs great, no issues just wanna see if I might be doing any harm to the engine by not keeping the stock configuration.

 

I have 4 corner breathers on my FE because I got tired of the PCV sucking oil which can eventually lead to detonation problems if let go too long. Without the PCV valve you definitely want to run the engine warm enough to drive off any moisture. I have a 180 T-stat and it seems to keep the inside of the valve covers dry. The alternative is to get good valve cover baffles and an adjustable PCV which costs around $50.

 

How does the PCV suck oil? I thought it was a one way valve, I was told that you need to create some kind of pressure in the engine to off gas the fumes and the breather doesn't allow that to happen.

 

It is a one way valve. It sucks blow by gasses out of the crankcase to be burned and exhausted down the muffler. The one way function is a safety feature that keeps any possible back fire from blowing back through the PCV and igniting those blow by gasses and blowing up the crankcase. PCV valves replaced draft tubes for environmental reasons on gas engines in the '60's. Diesels used draft tubes until more recently. My wife's 2002 diesel came with a draft tube.

At around 2500 rpms the oil oozing over the rocker arms turns to mist. It takes good baffles and properly weighted PCV valve to keep from sucking LOTS of oil mist. Let enough mist get into your cylinders and it forms hot spots that are very bad for an engine under heavy load like towing or hard acceleration.

 

The pcv sweeps the engine of gasses. IMHO if it was pulling oil it was because oil was available for it to pick up, and I am going to stick my neck out and say because of a well worn engine.

A breather cap on the drivers side and pcv on passenger with hose connected to carb base should make it happy.


John

 

Just for point of reference, PVC stands for Polyvinyl Chloride. PCV stands for Positive Crankcase Ventilation.

 

I know I noticed that. It was auto correct on my phone

 

A worn engine will have more blow by and thus increase oil consumption but that's not the case for me. I've played with baffles, restricted oil to heads, and even had an adjustable PCV valve. If you run the freeway with a 4.10 rear end at sustained 2900 rpms like I do, you may suck oil unless your baffle system and choice of PCV valve are spot on. If you do get oil through your intake, then I would put a vacuum trap between your PCV valve and where ever you connect it to manifold vacuum to see if your PCV valve is sucking oil or your intake has a leak. Oil in combustion chambers can be very bad news. Or you can use just breathers like me, or you can use a draft tube. Regardless of how you do it, you need a way to vent your crank case.

 

How does moisture get into the engine? I live in NM, extremely dry so I don't know if moisture is a concern or not. If I just remove the PCV and replace it with another breather how will it create moisture inside the engine? Also should I replace the current breather with a oil cap? It seems like the PCV wouldnt have anything to extract if the fumes are being released thru the breather.

 

Moisture is a by product of burning hydrocarbons (gasoline in this case). In the cooler states, you can see steam coming out the exhaust and sometimes even water pouring out the exhaust until the engine gets well warmed up. Moisture enters the crankcase via blow by past the piston rings. Without some type of valve cover vent, you will build lots of moisture in the form of snotty looking oil in the valve covers. This is why you need to get the engine over 180 degrees to drive off the moisture.

If you run a PCV valve or a draft tube you want an opposite side breather (like jowilker said) to sweep the crankcase. If you go with breathers only, then I would have at least one one each side.