Air Filters - Outer & Inner

[Gem99ultra]

I've noticed in my Shop Manual for my L3400 they show two air filters - the normal outer air filter and an 'optional' inner filter that slips inside the outer air filter. Does anyone use both air filters? And if so, is there any true benefit?

On the other side, is it detrimental to use both outer and inner filter for everyday use?

'

 

[arlen4720]

I think it's a good idea to use both. The idea behind two, is that you get some protection if the outer one disintegrates, and you get some protection during outer filter changes. You don't need to change the inner one very often. Every JD diesel that I've ever had, has used 2 filters.
When you say the inner one slips inside the outer one, do you have to remove the inner one with the outer one? That's not what I'm used to seeing.

 

[bdog]

Always use both. The inner is a safety measure in case something gets past the outer. If you properly maintain the outer the inner will practically last forever.

 

[Gem99ultra]

I think it's a good idea to use both. The idea behind two, is that you get some protection if the outer one disintegrates, and you get some protection during outer filter changes. You don't need to change the inner one very often. Every JD diesel that I've ever had, has used 2 filters.
When you say the inner one slips inside the outer one, do you have to remove the inner one with the outer one? That's not what I'm used to seeing.

No, they are two totally separate filters, one being small enough to fit inside the larger outer filter.
But thanks for the reply - I was afraid that a special air filter housing should be used, however there was no reference to such in the Work Shop Manual about a different housing.

Thanks again for the fast responses.

Jim

 

[murphy1244]

A lot of Tractors use the two Filter system.

 

[RG1]

Always use both. The inner is a safety measure in case something gets past the outer. If you properly maintain the outer the inner will practically last forever.

This^^^^^^^^

All my diesel tractors have had the 2 filter system, as have my commercial gas ZTR's. When you consider how much dust the air filter on a tractor or commercial mower may see in a day of hard use, the inner filter is a huge plus. The outer one traps most of the dust/dirt that makes it into the air box, and the inner one catches the smaller particulates that do make it through the outer filter. As was said above, I rarely have to change an inner filter as long as I take care of the outer one, which I do.

OP-
When you remove your large outer filter, you should be able to look inside of the housing mount that stays attached to the tractor and see the recess that the inner one fits into. It is a snug friction fit. The inner one doesn't ride inside the outer one, but fits into that small recess. There is a small amount of air space between the two filters.

 

[LJH]

I just checked the secondary air filter on my 3120 w/1200 hrs. It's still perfect. I change the primary regularly - super-cheap insurance.

 

[Travis_R]

I've noticed in my Shop Manual for my L3400 they show two air filters - the normal outer air filter and an 'optional' inner filter that slips inside the outer air filter. Does anyone use both air filters? And if so, is there any true benefit? On the other side, is it detrimental to use both outer and inner filter for everyday use? '

Always use both for sure. You probably won't replace the inner filter near as often as the outer filter. You'll be able to tell when it needs replacing.
My Hustler zero turn mower has the same filter system you are referring to. I replace the inner filter every 2 or 3 years, and the outer filter every couple years, or if it gets real dirty before then. I personally don't recommend using compressed air to blow out paper air filter elements. You never know if you might blow a tiny hole in it. I find that it's best to just go ahead and replace them and be done with it.

 

[Recoveryhill]

I bought the inner filter. My oil analysis for silicates and such was off the charts low and might have been with only the outer filter but I feel better with the two filter system.

 

[Dozernut]

When I bought my ZD 21 it only had the outer filter. A mower operates in a dusty environment and needs an inner filter. There was a socket for the inner filter, but evidently they forgot to install it. I had extra inner air filters in the shop for the RTV. They both take the same filter, so I stuck one in. Got a replacement from the dealer for the one I used, but it pays to go over your new machine and check things out, bolts, nuts, filters, clamps, hoses and etc.

As a side note the B2630 takes all the same filters as the ZD and RTV, so when I stock up, this makes it easy to buy filters.