My dad just bought a 2003 Tacoma with the 3.4L. There is oil leaking into the air box through the air intake tube. I pulled the upper air plenum and there is oil going down each tube. It is smoking pretty bad from burning the oil. Its been going through a quart about every 150 miles.
What could it be? I replaced the PCV so its not that.

 

no body has any ideas?!

 

Do you have any oil leaking elsewhere on the motor? Id check your upper intake gasket between the plenum and the lower manifold. See if there is oil leaking beneath the plenum...keep us posted.

 

there is no other oil leaking anywhere

someone suggested a bad block but I dont see how oil can go from a cylinder up against the air into the intake tube and then into the air filter

 

Check that your PCV valve isn't plugged up or just not working, that's the usual cause. How does your valve cover look, any oil leaking from it?

 

Air you sure it has a PCV valve installed? If so is it working correctly? <--If the PCV is properly working then its "blow-by" and is being cause by leaking valve stem seals or guides, or worn piston rings. Next step is to check compression.

 

Got a new PCV valve from Toyota and still same problem. How can oil go from a cylinder all the way up the "U" of the intake manifold and down to the air filter while fighting the air being sucked in? If there wasn't oil in the intake tube and just smoking then I would understand but to fight gravity to climb up into the air intake and against air flow doesnt make since to me.

 

The PCV or Positive Crankcase Ventilation system is meant to relieve the air pressure produced in the oil pan and under the valve covers by all the moving parts. The pressurized air also has oil vapor mixed with it and the mixture is siphoned into the air intake to be burned off. This is why when you remove the upper plenum there is an oily black mess inside. If there is enough oil to leak back into the intake tube then you may have some blow-by or another engine problem.

 

What he said above. I made an oil catch reservoir out of a air compressor water separator. It goes between the PCV valve and the throttle body. It is amazing how much oil it collects. This is usually where the oil comes from. I do not think it will hurt anything, but I hate the oil covering the whole intake system is why I installed mine. Maybe I can post some pictures...

 

Crank case pressure will push oil out just as easy as it can pull it in from vacuum. Ifs its consuming oil and PCV system is fine then its mecahnical and needs engine repair as i stated earlier. "BUT" theres one more thing. Removing the vac line the PCV is connected to from the take while the engine is running putting your thumb on the hole of the vac line that goes back to the crank case does there appear to be "alot" of vacuum? Are you sure you plugs the Vac line in its correct spot? <-- IF all clear engine repair is in order. Whats the mileage and oil change intervals on your truck?

 

SLUDGE!!!!!!!!!!!!!!!!!
Took it to local Toyota tech and there is sludge galore.

 

Ah wow. The sludge would mess with the crank case pressure and thus oil.... Good call on that tech.

 

hahahaha

its funny because it didn't happen to me! (sludge)

:

 

Gotta hate previous owners who just don't care enough to get an oil change...

 

^Indeed

 

When i worked at Saturn back in 08, this guy brought his 06 Vue 2.2L in for an oil change. We did it and he came back later that day saying it was overheating. I pulled it in and the rattling noise from the valvetrain was deafening! I pulled the valve cover and found the top of the head was caked with sludge, but what was interesting was the sludge had crystallized and completely clogged up the oil passages to the valvetrain. All the cam bearings had worn away and the cams had eaten into the head. He had just bought the car 2 weeks prior and fortunately he bought an extended warranty. Needless to say, he got a new engine! So that's what can happen if you don't change your oil for 38000 miles.