my 2003 toyota avalon started smoking at the body shop. thick white smoke, does any one know why!

head gasket

We recently bought a 2003 Toyota Avalon with about 50k miles. Shortly after we bought it, we noticed the white smoke on start-up and sometimes on acceleration.

I took it to my mechanic, and he couldn't find the problem with his normal checks - compression tests, etc. I did not ask him to remove the head and check for sludge. I put is some 'sludge removal treatment' with a couple of oil changes, but it did not solve the smoking problem. Along with the smoking, I noticed that I consumed about 1/2 quart of oil each week.

One day I decided to disconnect the line from the engine intake to the PCV valve, and to plug off the line. I left the PCV valve open to the air to avoid any pressure build-up in the engine. Well, the smoking stopped and the car does not consume oil any longer - seems like the oil was going out through the PCV valve and not due to ring blow-by.

The car has run good now for the past few months, and my gas mileage has even improved slightly. I believe the engine vacuum was too high during start-up and acceleration, and was causing abnormal vaporization and carry over of some of the components in the oil. I still don't know if I have any sludge deposits in the engine, but I continue to use good oil and change it every 3,000 miles. I don't see any evidence of sludge and the car runs great.

White smoke usually means it is burning water so it's probably a leaking head gasket, blue smoke means burning oil, black means excessive fuel.