awd911

I recently replaced my 3.6 engine with a used 33k mile motor. (Except for the case, I have all of the parts from the old motor.) There are no leaks and the motor idles and runs strong. After reving to about 6k rpm and letting the motor come down to idle, the engine puffs/blows noticeable amounts of blue smoke. The smoke is more noticeable after the car is allowed to idle and then is reved. It also does this when in traffic after pulling up. The car runs fine at track events and does not seem to have this symptom.

Initially I thought that the rings needed to reseal to the pistons. I also checked the oil level for overfilling. I've considered some sort of sabotage by the tech that installed the motor, like blocking the oil breather tubes or reversing them. Now I am thinking that valve guides are worn, except I have not heard of this happening on engines with worn valve guides. I will check compression and then move on to a leak down test.
Any feedback will be appreciated.

awd911

Found the problem!! The blow-by was caused by the engine vacuum.

Bill Verburg

What was the solution?

Tuner1

Does this make sense? Can someone please explain the connection to the original poster's situation?