Oil blow by through vale cover breather vent

[Sgt Mitsu]

I take it no one has had this problem then........

Leak down was nominal and within limits for factory standards.

Pcv valve is good.

Going to replace the jet valve and see if it cures the problem that only arose after the discovery of a broken jet valve.

300 miles more and still runs good..even a little better fuel economy.......

Tough little trucks...they break and still run.......

[geezer101]

The jet valves only act as a secondary inlet to the combustion chamber from the inlet manifold so it "shouldn't" cause blow by - unless something scary has happened like a crack between a jet valve gallery and an oil gallery has occurred (don't know if this is even possible...) 4G54 MCA-JET valve heads weren't sold here in Australia - and the few mechanics that have run into them do things like weld the combustion ends of the jet valves shut and cut the auxillary rocker arms off due to their lack of understanding of how they work. Their excuse usually goes something like "they burn out anyway..."