Hi guys I have a problem with my 390 my air filter in the carb keeps getting full of oil and my truck runs like crapp then I change the air filter and it runs ok. does anybody know where this oil comes from or why does it collect on my air filter. What can I do to fix the problem thanks in advance because I know somebody has the answer.

 

Do you have the stock air cleaner on it?

If you do and have the line from the valve cover breather going into the air cleaner it might be blowing oil through the hose... Just a guess on my part...

Anyone else?

 

probably pcv valve , but if it's a lot of oil then you have a bigger issue ,lots of blow by
could be rings .

 

Thanks for responding so quick guys yes I do have the stock air cleaner with the breather hose from the valve cover going to it, should i cancel this hose and just buy a regular oil cap to stop oil from soaking my air filter or should I install an oil catcher on the breather side to solve this issue, or do I have to install a second one on the PCV side also what do you guys think. my compression is around 120/125 psi the motor has about a year that it was rebuilt,spark plug burn OK no smoke coming out of the exhaust. Now someone told me that it could be the high volume oil pump that floods the valve train.and because the oil doesn't drain fast enuf that's why oil is bean sucked thru the breather hose, does that make sense.

 

Is the PCV system working properly?

 

yes it is I installed a new one like a month ago and the issue still exist

 

A high volume oil pump will contribute to this.

I know this is a fairly recent rebuild, but check under the valve covers anyway.

Did you used neoprene valve seals? It's a bit early for them to be falling apart, but if one has, it could be blocking the drain backs.

The hose from the oil filler to the air cleaner is supposed to be drawing air into the engine.

The PCV regulates air coming out of the engine. I see you just installed a new one. FE spec item? New, Motorcraft? Grasping at straws here....

 

2x with what others have identified but I'll pass on what I've read about the FEs and leave it up to you to conclude what might be going on.

FEs tend to over-oil the top end and under-oil the mains. I recall it was described as, "Four quarts feed the valves, one quart feeds the mains, and one quart is in the pan". That's why some will put Holley carb jet under the rocker shaft bolts to force more oil to the mains. Ford's solution for the hi-performance 427FE engines to live at high RPM were the FE side- and top-oiler blocks.

Another possibility is that the shroud that shields the PCV on the underside of the valve cover is missing. With the vacuum generated by the carb, splashing oil could be getting sucked up into the carb.

But wait, the PCV hose should connect to the carb spacer and should not affect the air cleaner. Could the hose from the PCV be connected to the underside of the air cleaner causing the carb to inhale oily air?

Your system should be configured like the image below- only with the PCV installed in the valve cover grommet.

 

Thanks once again for the quick response guys. HIO SILVER thanks for the image that is the way my system is hooked up the shroud is in both valve covers,now I did put two 5/16 dia brass rods, one on each side of oil passage to the valve train to reduce oil flow to the top and also so the pan would have enough oil for the pump to keep lubricating the system, now I see how you divided the oil 4 on top, 1 in the mains and 1 in the pan. I knowrest that to thats why I added the reducers I made to keep more oil in the pan, I went ahead and added one more quart making it 7 total. do you think this extra is bean added to the top causing the problem I'm having? Thanks again in advance.

 

The air filter is way too high. You have a vent problem. Regardless of the PCV being new are you getting adequate vac to it? Pull the cap with the hose on it and start the engine. Are you puffing out the top with air? Regardless of time on rebuild you may have broke a ring. If your vent was working properly you would be burning oil. You can't be filling the air filter without burning oil. It will suck at least a portion of it down the carb.

 

Thanks for all the help guys, I'm going to look more in to this to try and solve the problem now that I have a better idea of what to look for I will update when I solve the issue thanks again.

 

The air cleaner side is the pcv vent at normal speed but is also designed to let blow by escape during hard acceleration when there is more blowby. They used to make a simple pcv valve tester that just laid over the vent hole and the vacuum was read on a gauge.
Do you have the little filter on the end of the hose inside the air cleaner?
On a separate note, high volume pumps are over sold. Very few street engines need more volume and quite often they can cause detrimental affects.

 

willowbilly3 I do not have the little filter inside the air cleaner its just the end of an elbow that the hose from the breather cap hooks up to it,I think I know what you are talking about does it look like a pocket with a piece of sponge in it, is that what you refer to as the little filter, no its not there do I need that to stop oil coming in from breather cap, and not getting to my air filter.

 

That little filter is inside the air cleaner housing, but outside the filter, correct?

If so, you need it to filter the air going into your engine.

It will not stop the oil though, you still have to hunt that down.

 

Are you saying that you are adding 7 qrts of oil to a 6quart system? Thats what it sounds like in the above statement you made. Fe take 5 quarts plus one for a new filter when you do a complete oil change. You may have excess oil causing a restiction in you pcv system thus causing backpressure from the crankcase to blow oil out of the breather intake tube into the air cleaner. Unless you added a larger oilpan you should not need more than 6 quarts.