i replaced my air filter, both regular and foam pre filter. I had difficulty inserting foam filter into housing, and not sure if its in correct. Where is there instructions on how to insert foam?

 

I don't know if there are any. Yeah its a pain in the butt to install, especially by just pushing it straight down and then trying to fit it in the slots. I felt around the outside of the filter the best I could to pull down the filter at the slots but I could only feel 3 sides of it. I guess if someone really wanted to you could unbolt the filter box to install that filter.

 

What would happen if I took out pre filter, and just relied on drop in filter? It's still filtering, right?

 

The foam filter is a seperate "chamber" for the paper filter. The intent is that the foam causes more restriction so the air is drawn through the "main" part of the filter. If the main part gets plugged (with snow or whatever) then it will draw air through the foam and that section of the paper filter. I would leave it in for it to work as designed and NOT draw through that section of the filter unless necessary.

You can see that the main part of the filter is dirty but the secondary is clean.

Just ram it in from the top

 

Or do this........

 

Darren,
Thank you for the explanation about how the stock filter works . I was not aware of the purpose of the secondary filter. By the way are you still seeing partials in you fuel filter changes ?

 

Darren, something fell off your truck!

 

Good thing no one was behind me when all the stuff underneath fell off. That would have been a heck of a wreck

I just realized that the secondary part of the paper filter would be clean anyway becuase the air would be filtered by the foam. But on mine the foam is clean so I am pretty sure that is how it is supposed to work.

Yes, I am. My initial flying off the handle was at 40,000kM and I am at 75,000 kM now. I have changed the DFCM filter twice and both times there was the same fine metal shavings in there. It HAD to come from an external source because there is no way the injectors would survive 35,000 kM of that stuff. Truck is still running strong. Plus the stuff I found is ALL steel, NO aluminum. Life is good