I cut open the Bosch Distance Plust 3422 that I use on my 2003 Toyota Sienna.
I will include some details that are intended for folks not so familiar with oil filters.
Here is a picture of the filter can, then the base with the orange anti-drainback valve, the spring that is at the top "dome end" of the can and then the filter media.
The oil flows in through the small holes in the base plate.
In this picture, they are covered by the orange anti-drainback valve.
The anti-drainback valve is a simple flap that permits the oil to flow up (as oriented in the picture) into the filter, but not back down into the motor.
This is to hold oil in the filter...which wil provide faster oil flow when the motor is started, as compared to a filter full of air (if the oil was permitted to flow back down into the moter when shut down.
This is important for filters that are installed with the base down, or lower than the dome (top) end of the filter.
The oil will then flow up inside the can, but on the outside of the filter media (the part that you see in the picture).
The oil wil then flow through the pleats of the filter media and then down through the hollow center area.....and back into the motor through the big hole in the center of the base plate.
As the oil is PUSHED into the oil filter by the oil pump, there needs to be a pressure bypass in case the filter media becomes clogged or if the oil is cold and thick.
Unfiltered oil to the critical lubrication areas of the motor is FAR better than no oil.
Some motors have a pressure bypass built into the motor.
Most oil filters have one (for motors that do not have one).
On THIS particular oil filter the pressure bypass valve is in the center of the top of the filter media end cap (dome end).
There is a coil spring under a flat metal disk in the center of the metal plate that is at the top of the filter.
When the pressure drop across the media reaches a certain value (may vary between manufacture's application specifications), the disk will move down, letting oil flow from the TOP of the filter, down through the center..and out the big hole in the middle of the filter.
This bypasses the filter media and makes sure that the motor still gets the critical lubrication that it needs.
The metal strip that is in the media is used to crimp the ends of the filter media together.
The media starts out as a flat strip of material.
It is folded into the pleats that you see and joined at the ends to make a circle of pleated filter media.
The hollow center part inside the circle of media is supported by a metal tube with holes in it, which prevents the media from collapsing under conditions of thick oil or media becoming clogged with dirt.
This picture shows the pressure bypass (the small darker disk in the middle of the top plate).
I will include some details that are intended for folks not so familiar with oil filters.
Here is a picture of the filter can, then the base with the orange anti-drainback valve, the spring that is at the top "dome end" of the can and then the filter media.
The oil flows in through the small holes in the base plate.
In this picture, they are covered by the orange anti-drainback valve.
The anti-drainback valve is a simple flap that permits the oil to flow up (as oriented in the picture) into the filter, but not back down into the motor.
This is to hold oil in the filter...which wil provide faster oil flow when the motor is started, as compared to a filter full of air (if the oil was permitted to flow back down into the moter when shut down.
This is important for filters that are installed with the base down, or lower than the dome (top) end of the filter.
The oil will then flow up inside the can, but on the outside of the filter media (the part that you see in the picture).
The oil wil then flow through the pleats of the filter media and then down through the hollow center area.....and back into the motor through the big hole in the center of the base plate.
As the oil is PUSHED into the oil filter by the oil pump, there needs to be a pressure bypass in case the filter media becomes clogged or if the oil is cold and thick.
Unfiltered oil to the critical lubrication areas of the motor is FAR better than no oil.
Some motors have a pressure bypass built into the motor.
Most oil filters have one (for motors that do not have one).
On THIS particular oil filter the pressure bypass valve is in the center of the top of the filter media end cap (dome end).
There is a coil spring under a flat metal disk in the center of the metal plate that is at the top of the filter.
When the pressure drop across the media reaches a certain value (may vary between manufacture's application specifications), the disk will move down, letting oil flow from the TOP of the filter, down through the center..and out the big hole in the middle of the filter.
This bypasses the filter media and makes sure that the motor still gets the critical lubrication that it needs.
The metal strip that is in the media is used to crimp the ends of the filter media together.
The media starts out as a flat strip of material.
It is folded into the pleats that you see and joined at the ends to make a circle of pleated filter media.
The hollow center part inside the circle of media is supported by a metal tube with holes in it, which prevents the media from collapsing under conditions of thick oil or media becoming clogged with dirt.
This picture shows the pressure bypass (the small darker disk in the middle of the top plate).
