Hello all, noob to posting. My recently purchased 1991 f150 5.8 has leaky valve cover gaskets so I decided to check it over a bit further. Along with the valve cover gaskets I was planning on replacing the spark plugs, EGR valve, pcv valve along the way. When I removed the upper intake manifold and set it on the ground I noticed about a tablespoon of dark oil come out of the very back port of the intake. The lower intake is very dirty and I know the pcv valve is oily. I see numerous posts where this is normal and just as much that say I will need to rebuild i.e. rings bad. Can anyone let me know which is true and what is the best (cheapest) course of action. This is a truck I don't plan on driving much...wood hauler.

 

clean the passages.. the PVC side and the air breather side if it cant breath it will pull oil into the intake

 

I agree. Make sure everything under your valve covers is clean. Also, if you can get your hands on a Motorcraft PCV, that's the route you should go. I had issues with oil being blown out until I replaced my new brand X PCV with a new Motorcraft PCV.

 

As far as needing a ring job you would more likely have smoke at the exhaust. If you want to be sure do a compression test. All cylinders should be close to the same.

 

If the exhaust or intake has been modified, you need to recalibrate the PCV system.

I freer flowing exhaust can cause the engine to spit oil out the breather assembly. The PCV would need to be opened up to except more airflow. This can be mistaken for bad rings etc.....

 

Thanks for all the input. Once I pulled the valve covers there were much cleaner than I would have thought. What or how would you clean the passages. A simple cleaner and a wire brush?