Excessive crankcase ventilation
 

I have a 2006 Hummer H3 with the standard 3.5 liter vortec that has 189,000 miles. I recently began having problems with excessive oil consumption. It was only using a quart every 6 weeks but not leaking a drop (to be expected for 180,000 miles), but my "Helpful" brother-in-law overfilled it and now it uses about 2 quarts a week. Some is leaking and blown all over the engine compartment but not 2 quarts worth. Today while trying to see where the oil was blowing out from I removed the oil filler cap and it was blown out of my hand by massive pressure! Can a gummed up PCV system be the cause?

the pcv system draws air thru the filter/air in system thru the intake so it creates a slight vacume, not pressure.

was it running when it BLew?

the over fill may have caused damage. do we assume its not over full now?

at 190000 it could be anything!! congrats on the miles, its inspiring to us!

Worn piston rings will cause engine to burn oil and excessive crankcase pressure. What weight oil are you using? Overfilling is definitely NOT good! See any smoke out the tailpipe? PCV is part of the valve cover. Check if the hoses pinched? With the mileage chances are it is internal, especially if it smokes; rings or guides.

GL

It is no longer over filled. There is no noticeable smoke from the tailpipe not even at start up. Yes the engine was running when I removed the oil filler cap. I was already considering a complete rebuild, I was just want to make sure its not over kill, but at 180,000 miles I guess it's due. I am just surprised (and pleased) how well the engine still runs despite the miles and the oil issues.

How much was it overfilled? If there is too much oil, so much that it reaches the crankshaft, the rotating will actually stir it up so much that it foams and then the oil cannot be pumped through the engine, thus starving the engine of oil. Thus a burning of the oil will occur. I'm curious to know how much oil he put in and then how long you drove it after it was overfilled.

forgot,, pressure could blow a gasket, seal,,somewhere.

rebuild? yeah, or long block from rebuilder.

There is a simple hose (no pvc valve) that runs from the valve cover to the intake resonator box, it vents the crankcase. It's got to be clogged to build the pressure that you described.

A long time ago I read where someone found a paper part number label packed into the vent opening inside the valve cover of his truck. Removing it fixed his similar problem.

There has also been some talk about problems with the vent's oil baffle inside of the valve cover over the years too.

hose blows
 

if the hose was plugged,the first thing to blow would be,,,the hose! and you wouldn't notice anything as was recently reported here by someone who left it off.
this guy said it blew the cap out of his hand!
the hose is a simple push on since its vacume.(which I cant spell)

Yup, sounds like the vent outlet in the valve cover could then be plugged up somehow. Or the hose already blew off and that's the source of the oil spray in engine compartment.