PCV system problem

97 windstar 3.8

Little recent history just in case it's relevant. I was suffering very poor fuel economy, no codes. It appeared to have been caused by a split in the rubber connector between the MAF sensor and the air intake manifold so air was entering mid way. Which I have replaced along with a new MAf sensor

I am now getting oil in the air intake (air filter/MAFS) unit.

It has to be entering from the PCV system as I'm seeing oil in the vacuum pipe after I had cleaned it. So I changed the pcv valve with new gromit and checked for leaks in the pipes, cleaned the manifold and air intake system fully but this hasn't solved the issue
What should I be looking for now? Valve cover gaskets? Intake manifold gaskets?
Thank you in advance for any suggestions.

A little bit of oil in there is normal. Is it just a light amount or is it substantial?

Enough to fill the ribs of the connecting rubber. The fuel economy appears to have dropped again.
I'm wondering if I have a vacuum leak, but I can't find one.

You could have a vacuum leak. Might want to check/change out the inside intake bolt grommets ("isolator bolts" as they're sometimes called) and port seals. Clean the EGR ports while you have the plenum off and check those plastic bushings on the IMRC actuators! (I think the '97 uses the little plastic bushings but I could be wrong). I hope that fixes it because if not, it could be something worse/internal like worn piston rings or something.

The PCV hoses can also crack. The elbow on top of the throttle body cracked on mine.
I also used genuine Motorcraft PCV valves because the aftermarket ones are hit or miss.....so much difference between them. The Motorcraft one should deliver closer to the specified flow under all vaccum conditions.

My '96 STILL gave me oil into the big flex hose after I installed a catch can system.

Related - is the rubber piece that connects the hard line to the airbox a dealer-only part? I can't find it anywhere but haven't resorted to calling the dealer. :)

-- Sent from my Palm Pre3 using Forums

Before rebuilding my engine, I had lots of oil in the PCV system. I can't say if it was mainly from blow-by, or from leaking valve stems, because both were addressed in the rebuild, but it now seems very clean.

FYI, before rebuilding I checked the oil fill hole for extra ordinary pressure, but I didn't notice much. However, the ring gaps were very large, something like 0.060", so the rings were clearly worn quite a bit. The engine had 310,000 miles, mostly interstate highway miles.

I have a 98 with the 3.8. I only have about 137K miles on mine. I last changed the air filter about 30K miles ago, which was four years ago. I took the canister apart today to change the filter and it was a mess of oil everywhere. Like you said, the ribs in the intake tube between the air filter canister and throttle body were full. It was running out of the bottom of the canister. About 15K miles ago, I replaced all of the upper and lower intake manifold gaskets, EGR valve, PCV valve, spark plugs and plug wires; all parts new OEM. I also had the rubber elbow on top of the intake dry rot/crack. The only way to get it is to get the entire tube assembly from your dealer. Having said all of this, I must be getting a lot of blow by, right? I change the oil every 3-5 K miles and have always used Valvoline Max Life high mileage oil, 5W30. What the heck can I do? I am really not interested in pulling this thing and rebuilding it.

A couple other quick things...I also replaced the little plastic/nylon bushings on the IMCR motor rods when I did the big intake manifold gasket project. Second, does a person really have to have the PCV system? Could a guy just remove the PCV valve and install a fitting of some sort in the grommet in the valve cover and route a hose down behind the engine towards the ground. Way back in the old days, they called that road draft breathers. It would obviously have a negative impact on pollution, but we are not subject to any inspections where I live.

What brand of PCV did you install, I had the same problem on a 98 with 3.0 engine and I installed a new motorcraft pcv and problem solved.

The normal air flow path for the PCV system is (1) fresh air enters the "front" valve cover from the intake between the MAF sensor and the throttle body, moves through the block to the "rear" valve cover, through the PCV valve and then into the intake after the throttle body (at the 90 deg elbow that was replaced).

It makes sense to get some oil flowing out through the PCV and into the intake, but this shouldn't put oil between the throttle body and MAF. The only explanation is that the positive crankcase pressure is pushing oil out both ports. Potential causes for this are (1) a block path through the PCV valve to the intake manifold (2) the system can't provide the amount of ventilation is demanded by the engine (which might be the caused by blowby). if you remove the pipe that goes in the front cover you might be able to to detect positive pressure at the valve cover.