I was sitting in the truck looked out the side mirror notice a little blueish smoke coming out of the tail pipe. So I tap the pedal and a large puff came out but isnt constant clears up. I know its oil . Ok here is my question I didnt notice this until I cleaned the tb and iac last night. Doesnt smoke while im driving that I can see.Is this symtoms of a cracked head? Iknow it can be rings. Second 3 weeks ago I blew a head gasket due to a clogged cat so I replaced the headgaskets, gutted the cat but never looked to see if the head was cracked the truck def doesnt have a stock idle anymore it is a lil rougher and smells like it is fat (due to gutted cat) and needing a new o2 sensor (next weekend)

 

blue smoke that builds up at idle and then clears at rpm can be valve seals. they can be replaced one at a time w/o pulling the heads using the air pressure trick or the string trick.