Air Cleaner Modifications

I did search, and paged through about 4 levels of results before I gave up. Pulled my cleaner cover off tonight to inspect my element on my M923 for the first time (I was told it was new when I bought it). That is a strange design. With all the talk about getting more power from the 855 I think that box might be a place to start. About 1/3 of the element is not really exposed. I mean it has that small gap and it can suck through the pleats but still. Mine was really only dirty on the part that stuck out. Seems, inefficient. Speaking of inefficiency the cartridge Maybe mine was a cheap one but I was not impressed. I can run the part number and get another but I would rather buy a better quality one. Didn't see any listed on the 5 ton parts reference, anyone find a higher quality element you really like? If we could source one about 1/2-3/4 inch smaller in diameter that would allow it to pull around that gap better. I know the filter is smaller but then from what I can tell it isn't using 30% of the one that is suposed to be there. For mounting/centering you could use small dowels or strips of wood as spacers. Just thinking about how to improve airflow without inventing the wheel.


My Filter numbers
19207-11604545
MFR-3ES68 10/05

Also found out that at some point prior it was leaking dust bad. I was not pleased when I stuck my hand in the engine air inlet pipe and came up with thick dust. Pulled it out and looked in the motor intake and there was nothing but a film of oil. Maybe that is why my truck had a new motor. Cleaned the inside of the pipe and will let it all dry for a day or two while I try and track down better air cleaners. There has got to be some higher quality stuff out there. Maybe mine is fleet service but...more air is power. I run K&N on the pickup and like it, I wonder if they will make a custom filter?

-Ken

is this a M939, or a M809 truck?

Sorry 923, fixed it in edit.

-Ken

made by donaldson for the military I believe and not available aftermarket in other brands.

I found it strange they did not use a dual inner/outer filter set up.

It's an old design I believe the 800 series 5 tons use the same filter. When they were designing the 900s in the 70s the military probably figured the filter worked on the 800s and the motor was staying the same so why change the filter and have to stock 2 different ones.

I was able to cross reference the shock absorbers though. I am working on finding the best replacement. I think I would rather have a less bouncy ride than more power right now.

posted in wrong thread

I wonder if you can take apart an old filter, take out the filter media and put in something like whats in the k&n's. Its probably available somewhere in sheets.

I found lots of them from other applications that will fit, flow better, clean better and will allow the truck to suck air at high volume from the entire filter. Including one from K&N but it is spendy at around $200. I will post with numbers and sizes as soon as I have time to organize it. I think you will see real HP and mileage gains with a few tweaks to that bottleneck.

-Ken

Ken I also have a 923A1 and mine has about a pint of oil in the housing and on the bottom 3rd of the filter. The oil is to trap any of the fine dust and dirt that may fall into the bottom of the can. Although this is not standard practice I feel it is a modification that was made in the desert storm theater for the reasons discussed. I posted this when I found the oil and others had the same thing in their trucks. The only problem I see with the after market filters like K&N is the only way they increase their air flow is to increase the size of the microns to allow more air in thus allowing more contaminates in to the intake. On gasoline engines it is bad enough but in Diesel engines it is a killer. I know there will be some that will dispute this observation but, it is a known fact that this is why the turbo charger was adopted on the a2 to boost the power while still keeping the air flow clean with the standard filtering systems. If it was a matter of just changing filters our great uncle would have already beat you to it. If your worried about the fine dust just use the same set up as mine and some others have.

Does yours cup the bottom third of the filter tightly like mine in the picture? That alone cuts flow. The elements I am looking at have thicker walls so the pleats are larger giving you a substantial boost in flow just with surface area alone. Looking at quality filters from OTR trucks I can tell that my filter is a rather low budget affair with some marginal filtering media. Checking it against some sock Peterbuilt filters on the shelf their pleats are larger and the filtering media is a thicker almost felt like consistency, and those are nothing special. I personally am shying away from getting a K&N and will instead find a quality OTR paper unit about 10 inches across (rather than stock 12) of the same height but with thicker pleating and of higher quality. It will require a small cradle to keep the filter in position until the housing is buttoned up but otherwise no modifications to the system at all. The filter will look smaller but if you were to unravel it and flatten out all the folds, the unit I am leaning towards is actually a much larger filter in terms of flow area. That is how you will gain flow without compromising filtering quality. Just by looking at mine (again I have no idea if I have an extra cheap one or not) the element is thin. I will post the number of the one I think is the best compromise when I am done looking through them.

-Ken

I think the bad boy I am settling on is a Fleetguard Cummins Air Filter - AF25354. It is 1 inch smaller in diamiter which will mean a 1/2 gap on that lower third of the housing, when you do that math it is a vast improvement for the media there regardless of who makes it. The filter media is thicker, the pleats are larger and overall it is cheaper. I will have to build a cradle to center the unit and will let you know what I come up with for that. I forgot to measure the center of my old filter so will have to wait until I get home from work to double check (unless someone has a AF canister apart and handy to check for me) before ordering. I will then take the truck out and replicate the exact same hillclimb that caused my EGT's to be too high and report back on what what if anything changes. I know the army picked the one they did but they are not always as concerned with performance as bottom line or supply lines. As for the turbo, well anyone with a thick milkshake will attest, sucking harder at the straw is no substitute for a bigger straw. Wait and see what my straight up, side by side testing shows before dismissing what might be an easy upgrade that will serve you better and save you money. All we are talking about is bringing the latest OTR heavy truck filtration developments to the 5ton.

-Ken

Do you have a pyro on the truck ? How are you measuring your EGT's ?

Is the fleetgard filter closed at one end or do you have to make your own endpiece?

I have a cheap key chain infrared thermometer. Not sure of it's overall accuracy but it will help me get comparison numbers. Suprfknman they are sealed on one end, same overall length, 11 instead of 12 inches in diameter with a thicker/deeper pleating thus much more surface area. I just need to confirm the inside diameter on the open end will work with the housing before ordering, I forgot to take that measurement this morning.

-Ken

I am very curious to know. I would imagine the original air filterdesign is very old and it worked for a long time so why change it is the military thinking. They are not looking to eek every last ounce of power anyways. I bet it would definetly help my a2 turbo motor.
Will

I really hope it works and makes a noticeable power increase. A friend on here has modified a k&m To fit his 816 but hasn't put the engine back to running order yet so we haven't been able to see if it is better or worse than stock. Keep us posted on your findings please..........

Any luck with the new filter fitting?
Will

Yep the inside diameter was sopt on so I ordered it. Living out past Hellingone Montana means it could be next week before I get it to try. I will try it out as soon as it comes.

-Ken

5 Ton Air-Cleaner Modification

This is something I have wanted to do since the moment I first saw how the cleaner box works. Everyone to their own I suppose but more air is more power. The way the housing is built effectively blocks 1/3 of the cleaner, that alone handicaps the system. The cleaner I found is less expensive, same quality and comparable in surface area. The smaller diameter allows the motor to pull air. In this case going with a smaller filter still allows more air because of how the housing is constructed. The NAPA version of the Fleetguard I used was common enough to be in stock at my local store. I bought one of those as well simply because they were running a 50% in store stock filter sale. Seemed dumb not too...

Numbers:
Fleetguard -AF25354
NAPA - 6664

Do what you will with this information.

-Ken

https://www.youtube.com/watch?v=c8TeD04Qdoc