Air filter

The OP doesn't say which air filter he replaced the old one with. Substandard, read cheap, filters give substandard results. Start with the easy stuff, make sure the filter is the correct one for your engine. Next, see if you can step up one level and still make it fit. IMO, your engine will tell you if it needs something else. I use the gauge to confirm what mine's telling me.....Dennis

Cummins will pull 40 inches of vacuum and it wont hurt them. I'd pull off the filter gauge and throw it away. I ran my Peterbilt 400,000 miles and changed the dual aircleaners 1 time IAW the MP Ga. on the panel. Get an accurate MP Ga and put it on with a cash mount readout. 6.2 MPG isn't bad.

I would aslo check the connection hoses to air to air cooler and the intake side of turbo also, if these start to collapse that can caues issues also. Seen this many times in over the road trucks.

On mine, I thought fresh air came in through the center of the filter and filtered air surrounds the outside of the filter. If so, holes in the can would bypass the filter altogether - not a good plan. But I'm just going off memory when I replaced it last. I may have it backwards.

I would also be throwing road slush up in there in the rain and possibly draw it in to the filter through the holes, and that may be a critical issue - Freightliner issued us a recall for the water drain than can plug and the plenum can fill with rain water and get drawn in for hydro-lock. The fix was simple, but I know it's a real concern.

larry cad wrote:
I researched and discovered that the next size up filter was easily adapted to my engine. I did the mod and:
1. the gage stays where it should be with a new filter.
2. I got about 1.5 mpg increase in mileage
3. I "notice" better pull on hills.

Similar experience except I didn't see a MPG change.

It came with a 1200CFM filter and I installed a 1500CFM filter. It runs the mountains much better.
EcoLite

You can check the accuracy of your filter minder with 6' of plastic tubing with some water in it...X inches of water to make it trip.

I can understand and sympathize. I have an ISC 8.3 in mine and the gage would do the same thing. It drove me nuts. So, couple years ago I researched and discovered that the next size up filter was easily adapted to my engine. I did the mod and:
1. the gage stays where it should be with a new filter.
2. I got about 1.5 mpg increase in mileage
3. I "notice" better pull on hills.

I am a happy camper

The filter is held on with snap straps. There are standard straps available for the larger diameter filter. Then it's just a matter of making the ends work. Before I did this, I calculated the air flow needed for my engine and found that the stock filter had sufficient, but it still made the gage kick up. With diesel engines, more air is always better.

They should not drop all the way to the replace mark with a clean filter. If they do, then something else is going on - like the FM has failed. I think the problem is that the heat or vibration gets to them. what ever the case, they do seem to fail regularly.
The FM gives an excellent indication of when it's clogged to FleetGuards own specs. Like I said, I checked it to the air filters specs with a Mightyvac and it was right-on.
OTOH, if one has done anything to increase the boost an eng makes, the FM will be pulled down even sooner. On my own Cummins, I went from 26 PSI to 37 PSI and I draw a clean filter down to 20%. I'm just over powering it.

Scott, not to be snarky, but please explain how they're valuable. What do they tell you? Most will climb almost all the way to the replacement mark under hard driving, like hill climbing and then drop when reset. So what information is this archaic mechanical gauge telling you?

Air cleaners on diesel pushers need to be replaced every 2-3 years depending on how many miles you drive. A diesel filter should never be cleaned (blown out) and a good practice is to never remove one unless you intend to replace it.

Lastly, the OP is talking about a diesel pusher, not a pickup truck. You can't just mod the air pick up with a kit like you do on a truck. For 20 years, the air pickup systems (roof line air draw) have functioned without modification. You don't see aftermarket kits for DP's because it's not an issue.

Look your Filter Minder over carefully for cracks. Mine cracked and would indicate wrong. I bought a replacement and all was well.
FWIW, I used a vacuum pump to check the calibration of the new one to Fleetguard air pressure drop specs for used up air filter and it was right on.
So IMHO, they're well worth using.

As far as modifying the air box, if you are indeed over-powering the filter (with eng mods) then that can really help. Many operators have used what is commonly referred to as the Home Depot intake which is a 3 or 4 inch hole and a pipe connected that sucks in fresh air. The filter minder doesn't pull down afterwards.
Those that always bash any kind of eng mods will certainly have something to say about this kind of thing but those in the know will tell you otherwise and I've seen dyno runs that prove it.