I'm trying to figure out exactly what's going on with this truck. Got it last week for a steal since it had a leaking valve cover seal (which I've already replaced). Has 160k on it, a brand new transmission and clutch, and runs perfectly. But for some reason the air box is filling up with oil. I replaced the PCV valve and it hasn't made a difference.

Any suggestions? The engine runs perfectly, everything is nice and smooth and I intend to make it my daily driver. But the oil stain on the driveway is getting bigger and I can't for the life of me figure out why it would be blowing oil into the air box like it is.

 

Excessive blowby could cause it. Try pulling the oil cap while it's running. If it's blowing like a locomotive, then you might have bad rings.

 

Pulled the oil cap while its running and its blasting out air like mad.

 

How could bad rings cause excessive pressure like that. i am very curious as to how you have come up w/ that? Usually bad rings is associated w/ not having good pressure in the combustion chamber, in turn you would have low power? I would do a compression/ leak down test before you think your rings are suspect..

Mario

 

The air/fuel mixture will go past the rings on compression. This is called "blow-by". All engines have some, that's what the PCV (Positive Crankcase Ventilation) valve is for, to remove these gases, which are very high in HC, and burn them in the engine. A hole in the piston will cause the condition he describes, too.

Is this a 302 or 351? I have seen a few Windsors where the PCV vacuum port is plugged up with carbon, rendering the PCV valve inop. Pull the PCV valve out while it is running and stick your thumb over the end to see if you have strong vacuum there.

 

Thank you jas88 for backing me up on that. Some people should not jump to criticize something they don't fully understand.

 

Its a 302, and I just replaced the PCV. Is there an engine rebuild in my future?

 

Try the PCV test that jas88 suggested. Hopefully it's something simple like that.

 

PCV gets good suction, so its not that.

 

Sry if I came off like I was critizing you bro, I was really just looking for an explanation of how you got your answer. But I learned something new so its not a total loss.

I would look into still doing a compression / leak down test. Jasper also has blocks for a decent price if u discover u need a new one bro. Good luck

Look foward to see a new build

Mario

 

Yeah the next thing would be to do a compression check on your motor.

 

I know on the cars (89 Crown Vic) there is a PCV filter in the back of the block that will plug up causing your symptoms.

 

No worries Mario, we're all here to learn something.

 

I'm going to have a friend help me look over all the EGR and vacuum stuff tomorrow. Really seems like if it was a bad ring or valve seal or something I'd be burning oil . . . . the exhaust is completely clean. If we can't find anything it'll be time for a compression test.