I don't want to bore with too may details but I think the history is important here. I have a 97 F-150 4.2L the original motor made it 203K before the intake gaskets got so bad I didn't know if I should stop for gas or antifreeze. I had the motor replaced with a rebuit short block. The mechanic that swapped the engines commented that my intake manifold was COVERED with oil on the inside. At the time we attributed it to bad gaskets.

Now on to the rebuilt motor. I've got 15K on the new motor and oil consumption is about 1.5 to 2 quarts per 3k miles. I had the engine builder check it out. (Edit out lots of extranious detail) He pulled the intake manifold and it was again coated with oil. From his investigation he is stating that it is coming from the PCV line (PCV valve and line are coated with oil).

He said that he has seen this on VERY RARE ocasions. He does not understand what makes it do this, but his remedy is to install a "restriction" in the line from the PCV to the intake which reduces the flow.

Oil consumption is down, but still unacceptable in my opinion for a 15K mile motor.

QUESTIONS:

Is he feeding me a line?
Has anyone else seen this?
Why so much vaccuum (or pressure depending on point of view) on the PCV circuit?
I have read a couple of posts that elude to two hoses coming to the PCV valve on '97s. The Ford Shop Manual doesn't reference a hose "plan" that I can find. Should there be 1 or 2 hoses?


SIDEBAR:

Ever since I got the truck back from the oil investigation, the truck has a bad miss and back fire. It's coding a misfire on CYL 2. Comes and goes. I'm leaning towards coil pack as it was pulled from the 203K mile engine and it was original. Is is possible that this "restriction" that the builder put in the PCV line could cause the misfire?

Sorry for the long post.

 

I'm not all that familiar with your specific motor but I'll give ya food for thought based on over 25 years of being around cars/trucks. First, I will assume that you are dead certain that you are using the correct pcv valve for the application and that there are no issues with the breather system. With the engine running at idle, pull the pcv valve from the valve cover (I assume that's where it's located) and see how much smoke comes from the valve cover. There should be basically none on a good tight engine. If it's belching then you have a blowby issue. Now rev it up a bit. There should be little to no smoke. Belching/volumes of smoke = blowby. My first thought would be rings that didn't seat for whatever reason. BTW, that restrictor thing is a bunch of crap too; all that's going to happen is the excess blowby (I'm assuming and I bet I'm right) will be blown through the breather to elsewhere (probably the intake upstream from the butterfly valve).

I would personally do a compression test to determine engine health. If compression is low, squirt oil in each cylinder during the compression test. Do this one cylinder at a time. Make sure all spark plugs are removed, the throttle is wide open, and that the engine is warm when doing the test. Apply one good squirt from a medium pump type oil can. If there is a significant increase in pressure, you need to have a talk with the guy that rebuilt your engine.

**Personally, I suspect that the guy that rebuilt your engine understands quite well what I said above but would rather not get into it or worse yet (maybe for him) have you make a little *discovery*.