Auto-psy of a fluid filter (also known as oil strainer in some regions) on a Skyactiv automatic transmission

[SparkYellow]

It occurred to me yesterday that I could pry at the seam of the filter with a flathead as I did with the pan. Once I had an opening on the smaller end of the filter, I ran the screwdriver sideways down the gap to open up the rest. Some brittle plastic pieces flew out so I should have worn eye protection.

Before opening it up, I thought the filtered fluid enters the transmission from the large port. Now that it is open, it appears that the small port plays a more delicate role. It seems to be of the same diameter as the bolts that secure the filter. The small port gets access only to filtered fluid, and only from the vents between the two compartments. The paper element in the larger compartment, on the other hand, takes fluid from the bottom as well as the large port above.

Looking at the paper element, I don't see how metal pieces can go back in. We all read about how metal shavings are supposedly getting flushed around and back into the transmission. The shavings I saw on the magnet in the pan are thin like baby hair, I don't think they will pass through the filter.

Hold in I just noticed that bottom side of the paper element is different from the top side...

 

[SparkYellow]

The first picture shows the entire surface of the paper element facing the transmission (top side). The second picture shows the paper element through a small window that faces the pan (bottom side). You can see the lines that run perpendicular to the pleats in the top side. They are like threads that strengthen the pleats. I don't see the same threads on the bottom side. Considering how the bottom side is darker, I ran the flathead down the pleats and don't feel any bumps (threads).

There must be another exit for the fluid to enter the pan directly from the transmission. I didn't think about it at the time. The pan magnet picks up the large pieces first, and the fluid gets screened in the filter before going back in.