M60 Rough idle, blue smoke puff on startup

[bimmo_2007]

Good day fellas,

Recently, my 540 engine developed a rough idle, it also blew blue smoke puff on startup for just a second, I sprayed some carb cleaner on the intake manifold to test for intake leaks but the idle didn't change. However, when I pulled the dipstick nothing changed too but if I put my finger on the dipstick hole I can feel air suction through it. The idle is steady at 500 RPM.
Any suggestions?

Ahmed

[Tiger]

90% of the time of rough idle is the crank ventilation valve... which is a major bear to work on.

You need to pull the spark plug to see if there is abnormal indications.

You could have a leaky injector.

[bimmo_2007]

90% of the time of rough idle is the crank ventilation valve... which is a major bear to work on.

Is it the oil seperator valve OSV? hmmmmmm well that make sense.

You need to pull the spark plug to see if there is abnormal indications.

You could have a leaky injector.

I already pulled the spark plugs out, they looked good and nothing appeared abnormal.
Today, the blue smoke puff at startup disappered. But I was wondering if the O2 sensor could cause a rough idle. I noticed that exhaust smelled rich.