M9xxA2 Series Air (Filter) Restriction Guage Reading, After Changing Filter

[74M35A2]

Picked up a 1991 M925A2 in November from another SS member, love it, all that. Noticed the air filter restriction gauge was reading close to the red line (indicating to change it). Bought and installed all filters as PM, including the air filter (acquired this from a military surplus vendor, so it is supposedly the correct one?). Reset the gauge, took the ride for a spin, held the throttle down hard till top speed reached several times, slowed down, and found the restriction gauge to be reading the same thing, almost at the red line. Reset the gauge several times, and got the same thing each time.

I was expecting a reading of near zero restriction, as it is on new commercial semi-tractor trucks that we occasionally test. The old removed filter was wet, and had a dead frog in it.


Curious as to others readings, before or after a filter change. I will next do a short drive with the filter removed, and possibly same with the filter canister cover off (to remove the inlet snorkel from the equation). May also measure it with a vacuum gauge to attest the indicator's accuracy.

The Cummins 6CTA8.3 runs good, and the truck will reach and hold 67mph on GPS. Slows slightly on freeway uphills, don't believe pump to be "turned up", yet . Don't know what any other M9xxA2's feel like in power, so I can't easily compare that way.


Thanks in advance...

 

[FullSpecial]

Normal. Drove me crazy as well. Filter is just big enough and a lot of piping.

 

[Suprman]

I believe the filter can be rinsed clean and reused.