02roushtang

let me start by saying this is my first mustang i am and have been for years a 4 banger kind of guy. Anyways let me start. I bought a 2002 Gt Roush mustang about a month ago and noticed that when the car sits for about 1 to 4 minutes at idle and i tap the gas as the rpms decrease a small cloud of blue smoke comes out. i know this is not right but the dealership i bought it from said roush mustangs do that. when in fact i would love to believe that, but i am not dumb. I did a compression check all cyls where good to go. so which leads me to believe valve seals. this only happens at idle. any input would help seeing that the car is under warr. thank you very much

huey_33

Sounds like you're burning a little oil somewhere. Mine does the same thing when it idles and then I hit the accelerator but I don't have enough money to fix it and not enough expertise to take off the heads. Could be bad valve seals or bad piston rings. But since you did a compression test and everything was good, that kind of throws bad piston rings out the window. Valve seals are notorious for leaking a little oil once they get old. And welcome to the mustang world.

Blackvenom01

prolly alittle oil dripping down at idle and when you hit the gas it blow it out...youll prolly be ok for awhile maybe use some thicker oil 10w-30 or 5w30...

cliffyk

Typically that is caused, as you suspect, by leaking valve seals/guides. When you release the throttle the manifold vacuum rises oil is sucked past the seals/guides and burned.

You may find it smokes a bit on hard closed throttle deceleration as well, although under that condition the PCM will shut down the injectors after a short bit and there is no "burn" to burn the oil...