Throttle Body questions....

[wrd1972]

I have ordered a 52mm throttle body, I just removed my old one I have a some questions.
1. Why is there slight deposits of oil under the plastic top cap. It must come from that hose that connects to the right valve cover. Is this normal.
2. How does the TB get so grossly black and I assume carboned up and is it normal.
3. Are there mods that can be done to keep the throttle body cleaner like a valve cover filter and removing that hose.
4. What can expect out of the 52mm TB.
Thanks

[Trash man]

1) im assuming ur talking bout the PCV hose, yes some is normal u could put a breather there if u need, it just part of emission thats it.
2) its normal for it to be black, just use some intake cleaner and a rag to clean it
3) i dont think removing the hose will, it might but not sure
4) better air flow lol

[Injuneer]

Small amounts of oil are "normal".... large amounts might indicate a problem with the rings, or a plugged PCV valve.

The line from the TB to the valve cover supplies filtered air to the valve cover. That air is pulled through the crankcase and lifter valley to the bottom of the intake manifold, and out through the PCV valve on the drivers side, and then back into a vacuum port on the front of the intake, under the TB. If the system is working correctly, the flow in that line should almost always be from the TB to the valve cover. It is not the PCV line, just the filtered, MAF metered air supply. The connection goes through the area of the TB under the cover plate, and then to a port IN FRONT OF the blades, so there should be little or no vacuum.

If your PCV valve plugs, or you get excessive blowby on the piston rings, the system will start to build up pressure, the flow in the vent line reverses and the crankcase vapors entrain oil drops and blow them through the line into the top of the TB. Get enough oil in there, and it will continue out the port of the front of the TB blades, then get sucked through the blades, causing the large black deposits of gunk kthat you are seeing.

Some people have solved the problem of oil in the TB by placing a Deutsch oil separator module in place of the plastic elbow that connects the rubber hose to the valve cover. I would STRONGLY recommend against removing the hose and installing a valve cover "breather". The air that flows through that line has been measured by the MAF sensor, since it ends up in the combustion chambers. By adding a "breather" you are, in effect, opening up a closed system (emissions violation) and causing what is a small vacuum leak. The leak is nothing the long term fuel corrections can't take care of, but its simply creating a new problem, possible trying to cover up the old problem.

First, check your PCV valve and make sure it is clean and functioning. Second, check for blowby. In severe cases, if you take the oil fill cap off, and put your hand over the opening, you will feel air pulsing out. You can also listen at the opening for a "chuffing" sound.

I kept the PCV system intact on an 800HP nitrous LT1, mainly because I wanted to be able to pass emissions. Now the the car isn't street driven any more, only at the track, I've been thinking of removing the vent line, and installing a breather. But my setup does not use an MAF sensor.

[wrd1972]

I think the amount of oil in the throttle is going to be considered normal, I will change the PCV more often. I thought about a valve cover breather but I am going to take injuneers advice.