Hey Guys,

I was wondering if anyone know this issue?

I recently had the valve covers replaced. and now I am getting a puff of white smoke when I turn on the car then it goes away.

don't know if this is serious

 

White smoke is typically a sign of a coolant leaking into the combustion chamber.
This could be from a lower intake manifold (LIM) gasket or head gasket leak. LIM gasket leaks are a common problem with gen 6s. A single puff on start up could be the beginning of a bigger leak that will produce more white smoke.
Keep an eye on the coolant level in the overflow reservoir.

 

If you have a 3800, you may have a leak by what is known as the EGR stove pipe on the upper intake. This allow coolant flowing through the upper intake to and from the throttle body to spray into the intake with the fresh air the car pulls in. If this is happening, it must be addressed ASAP before you send so much coolant in it really messes with the engine and hydro-locks.

If this is bad, your options are:
- Replace the UIM
or
- Plug the ports on the lower intake (preventing coolant from going into the throttle body).