Oil in Intake

[Storm]

I took off my airbox and when I took the rubber boot off the throttle body, their was oil in there. Is this normal? There wasn't ALOT but enough to puddle in the rubber grooves.

Thanks
-noob

[QUICKSILVER462]

no, that is not normal.

[goldgp]

Mine had a little stain in the bottom of the tb when i got it,looked like oil was there b4 but its never done it since i had it.

[Warbeaver]

what kind of filter were you using?

[Storm]

K&N drop in. it was just in the rubber boot and there was only a small amount where the plastic breather from the upper plenium connects to the rubber boot.

[MrTube]

If the engine has high mileage and this is near where the crankcase vent is this is a common thing. Its caused by the engine having more blowby then the PCV valve can handle. My chev 350 was doing it a fair amount at 226K. If the engine has 150+K miles on it I wouldn't be surprised or concerned.


At least it was on older engines

[Warbeaver]

have you re-oiled your K&N filter yourself ever? what color is this oil? and are saying the oil is in the rubber piping going from the throttle body to the air box?

[Storm]

have you re-oiled your K&N filter yourself ever? what color is this oil? and are saying the oil is in the rubber piping going from the throttle body to the air box?

yes the oil is where you described it. It is engine oil,I know for a fact. its puddled in the little bellys of the rubber piping. right below where that plastic tube that runs from the upper plenium to the rubber pipe goes.

[GeosGP]

MrTube has the right idea. It's blow-by from the PCV.

[Warbeaver]

^^^

how is it getting enough force to go back out the throttle body, through the screen against the incoming air from the intake?

[GeosGP]

The PCV vent is between the MAF and TB I believe. That whole area is subject to vacuum at idle, so it pulls on the PCV system. If your PCV valve is crapped up, it won't seal properly and you end up with oil in the intake tract.

[Storm]

This wouldnt suprise me on a 200k mile engine, but i have only 65k miles. New upper and lower (aluminum) intake manifold gaskets from ZZP go in on Saturday along with valve cover gaskets.

[Bio248]

doesnt mean the PCV cant be bad. its like a $3 part, go buy a new one and replace it.

[MrTube]

didn't it used to be typical to replace pcv valves every 20K or so?

Btw, where is it located on the 3800 III? I haven't looked but itd be nice to know when I go to change it.

[GeosGP]

I used to pull them out and shoot some carb cleaner through them. If they still stuck, they'd get replaced.

[MrTube]

Before I traded the truck in on the GP I had the pcv get gummed up and stuck, It used over a quart in 1000 miles.. with a good valve it did a quart in 2K, mind you the engine had 200-226K miles on it during this.
Point being, the stuck valve caused it to slerp oil up big time. Tho with a proper working valve it ended up getting oil through the other vent due to blowby. By nowheres near as much.

[Silver GTP]

To find the PCV, go to the passenger side of the black plastic upper intake manifold and remove a small cover. It is underneath that cover inside the manifold. Iirc, it is a twist off cap.

[Storm]

To find the PCV, go to the passenger side of the black plastic upper intake manifold and remove a small cover. It is underneath that cover inside the manifold. Iirc, it is a twist off cap.

I have the l26, aluminum plenium.

[MrTube]

Yea. I also asked about the series III valve...

[Bio248]

the L26 plenum is the same.