Original Valve Cover breather

[DeepC73]

Hello,
I am wondering if the original 1973 ford 302 valve cover on the passenger side had a filter pad internal to the valve cover. I decided to add a breather cap to it to eliminate the need for a hose. When I do that it makes a mess and leaks oil on the passenger side. Is this normal? Why would it do that? Someone mentioned that there used to be a filter pad internal to the valve cover on the metal shelf to prevent this? Any information is helpful. Thanks in advance.

 

[DirtDonk]

I don’t remember anything on the inside of mine.
It wouldn’t normally be needed because air is being sucked in via that opening, rather than being pushed out. However they may have wanted something to act as a baffle or collector of vapors for when the system is not sucking.

Does the other valve cover have a good functioning PCV valve in the oil-filler cap?

 

[DeepC73]

I don’t remember anything on the inside of mine.
It wouldn’t normally be needed because air is being sucked in via that opening, rather than being pushed out. However they may have wanted something to act as a baffle or collector of vapors for when the system is not sucking.

Does the other valve cover have a good functioning PCV valve in the oil-filler cap?

Dirt, I’m referring to the passenger side. The vacuum and PCV is indeed on the drivers side. It appears to have increased crankcase pressure. I have oil blowing out of the weep hole of my fuel pump. It’s the third fuel pump to do this in less than a year. The pump functions perfectly. I’ve been suspicious for a while. The engine runs great, but oil is coming out of the breather on passenger valve cover and the fuel pump weep. I’m going to try to do a bleed down test tomorrow and see what I find out.

 

[cldonley]

As was said above, make sure your PCV valve is working. Often times if you're building up crank case pressure it's because of the PCV.

 

[DirtDonk]

What vacuum source is the PCV valve attached to?
How old is the PCV valve?
Is it original tubing, or has it been replaced?

 

[DeepC73]

I did a leak down test and need a little more help my friends. 3 out of 4 cylinders on the passenger side, the back 3 all have a leak down score of about 80%, the 4th is about 60%. The driver’s side is almost identical. During the test, especially on cylinders 2,3 and 4, the air was leaking out of the breather/ valve cover. I am therefore assuming that it is the exhaust valves leaking by. I plugged up the breather hose and the air comes out the weep hole in the fuel pump. When I rotated the crank about 1/8 turn the air stopped coming out of the crankcase/weep hole and was comings out the exhaust pipe. How should I interpret all of this. I’m a pretty fair backyard mechanic/ parts changer, but I’m out of my league here.

 

[DirtDonk]

When you’re doing a compression, or leak down test the valves in that cylinder should be completely closed. Obviously…
It sounds like they were in this case, but when you rotated the engine slightly the exhaust valve on that cylinder started to open. Sending your pressure out the exhaust port.
So that’s normal and good.

For the first question, no, leaking out of the valve cover means that the air was escaping past the piston rings. Not the exhaust valve.
None of the valves lead directly into the crank case unless the stems and stem seals are worn.
Another pathway can be through the PCV valve. If the PCV valve was still in the opposite cover, and your pressurized air was leaking past the intake valve, it could go up and through the tube at the carburetor and back into the crank case via the driver side valve cover. Where it could then come out the passenger side valve cover. It’s a long circuitous route however, so you’d have to do some more testing to narrow that down.

If it’s coming out of the valve cover, that’s bad. With any luck though it’s just a glitch hopefully. Try it again and isolate the PCV valve.
If you already had done that then it sounds like you have worn piston rings it sounds like to me.

You could try squirting oil into the cylinders and then testing it that way. The leak down test should show similar improvements to a compression check where adding oil would increase the compression by helping the rings seal against the cylinder wall.
I’m not sure how much it would improve a leak down test, but it might.
Maybe others have tried it?

 

[m_m70]

Does the other valve cover have a good functioning PCV valve in the oil-filler cap?

What vacuum source is the PCV valve attached to?
How old is the PCV valve?
Is it original tubing, or has it been replaced?

These are good questions??

 

[DirtDonk]

Semi-good.
Some Fords used a bit of hard line along with rubber hoses on the PCV that could get clogged up when things got older and worn. However as far as I know Broncos only used rubber of a larger diameter and they were not often found clogged.
But they still could be which is why I asked.

As for the vacuum source, many people plumb them into a single intake runner to get the vacuum and that is not sufficient for a couple of reasons.
One is that there may or may not be sufficient volume from one runner to pull the correct amount of air volume out of the engine.
The other is that you should never pollute a single cylinder with all of that gas and vapor and gunk.
It should always be in a common Plenum port like the base of the carburetor or carburetor spacer.
And rattling or not, an old PCV valve is still an old component and can wear out or get partially clogged.
At some point they all just need to be replaced rather than cleaned or ignored.

 

[blubuckaroo]

This sounds familiar.
Once we were attempting to use air pressure to hold the valves closed so we could replace the valve guide seals. The engine had been burning oil. The cylinders wouldn't hold air. You could hear the air blowing past the rings.

 

[m_m70]

Semi-good.

Sorry Paul........I was actually stating (poorly) that they were good questions and needed answers in order to help finding the solution to his issues. Just need an answer.

I run my PCV directly to the passenger side valve cover from the carb base and just a breather on the drivers side and have no issues.

 

[DirtDonk]

No worries. I tried to insert a smiley face but I don’t have that button in my phone browser.
I have the old fashion way of course, with the colon and and parentheses, but got lazy.