Oily residue...why?

[rcb280z]

On the F.I. L28's, the hose from the valve cover to the throttle body boot has an oily residue in it. I believe this to be normal in small amounts but mine has started to back up into, as far upstream, as my AFM. Could this possibly be my valve stem oil seals going bad?

[John Coffey]

How many (if any) quarts of oil do you need to add between oil changes? How many miles between oil changes?

[rcb280z]

It sits in the garage most of the time. Might see max 1000 miles between oil changes. Have put only about 160 miles since January this year.

[Zed Head]

I'm just guessing, but it could be a sign of a clogged PCV valve, which would be easier to fix than valve seals. If you look in the Emissions section of the FSM, you'll see a diagram of the flow pattern of the gases from the crankcase under different conditions. Under normal, mid-range RPM conditions, that hose adds a little bit of air to replace what the PCV clears out in tot he intake manifold. Under high RPM conditions, blow-by can push gases through both hoses, as described in the chapter. Worth a look at the diagram and a read.

My old engine did have worn valve seals and more blow-by than my current newer engine. The valve cover hose was oilier inside and my throttle body gummed up once. When I took the head off and set it aside, there was oil leaking down the valve stems on to the valve heads within hours. It burned about a quart of oil every 1500 miles. The newer engine is much cleaner, no residue in the hose.

Edited June 12, 2012 by Zed Head

[rcb280z]

You know Zed, I didn't even consider the PCV. I replaced the valve and hose about 2 years ago and guess I assumed it would still be fine. It's worth looking into. I'll post what I find.

[John Coffey]

You need to drive the car mote, a lot more. There probably isn't anything wrong, it just needs get up to temp and be run for an hour or more at speed on the roads.