crankcase pressure: why?

'04 Mazda6 sedan V6 / sport pkg / trans unknown:

ad says NEEDS ENGINE- Otherwise like new in and out....113,000 miles, Dk red outside, Black leather with heated seats inside, Sport Package with 17" rims and rear spoiler, Moonroof, Power windows, locks, tilt, cruise, power seats, Bose radio with CD player and controls on steering wheel. Runs and drives about a mile till crankcase pressure builds and pushes oil out of filler hole and exhaust. Needs to sit 10 minutes and will run again.

naturally, i'm thinking WTF causes this condition? ring blow-by? cracked piston?

or is there something really simple like a fubar PCV that would do it? because i could roll the dice on this.

oh, and i just noticed the trailer hitch.

You forgot something. Try again so i can actually reply.

Craigslist + crankcase pressure = No optimism allowed

Gambling on the PCV sounds like risky business for most kinds of cars...since you didn't say what kind of car then I'll just say it seems like you're being a little too optimistic. Craigslist hasn't bit you hard in a while, has it?

Bryce

i suck at the quote.

craigslist ad says:

Runs and drives about a mile till crankcase pressure builds and pushes oil out of filler hole and exhaust. Needs to sit 10 minutes and will run again.

Is it European? They certainly never figured out how to build a crankcase breather. If it pushes out the exhaust, thats probably a bad thing- like broken ring or holed piston bad, unless its turboed, if the drain is plugged with ick and swarf and other bad things.

That would be the same 3.0l in the Taurus. Nothing too exotic.

Sounds like the vent side is FUBAR. But remember that there's both a supply from downstream of the air meter, and a return line that's into the manifold. There are check valves on both ends, but even the supply line is supposed to blow off if the pressure is bad.

For a test, you should be able to vent the return side- or at least open it up, but make sure you block off the manifold return- that's a big leak- won't run so hot. If it's idling, and you feel massive amounts of vapor coming out, something is wrong. But a mile of build up- that seems quick, but it's not too bad- depending- pure blockage will build up pretty fast and cause problems.

Worthy of a look, and a quick test.

plug exhaust?

I recently fixed a vehicle with the same problem...as it ran it built up enough blowby to make bad things happen with the oil. It had a hole in the piston.

If you buy it, buy it with expectation (read: price) that you'll have to put an engine into it. If you don't end up having to do that, you got lucky.

Bryce