Can I trust that little gauge?????

Great post Airstreamer67. It is what I learned long ago in fleet settings and applies to personal vehicles.

The reason is that opening the air filter box to inspect the filter can introduce dirt into the engine. It's almost impossible not to get some contamination into the air system if the filter is removed for inspection.

The appearance of an air filter is not a reliable way to judge its condition most of the time. Ironically, air filter experts have said that a brand new air filter does not filter as well as a used one. The reason is that the layer of dirt on the filter element actually helps keep additional dirt from getting into the engine. What appears to be an absolutely filthy filter may be doing a better job than when it came off the shelf. Of course, when this reaches the point of restricting air flow to the engine, it becomes a negative. The gauge is designed to indicate when this is happening.

Thus the logic of trusting your gauges, unless you have other indications to the contrary, is a well advised procedure.

"on page 391 it says never to open the filter housing to inspect the air filter under normal conditions"

I do not understand this statement. I can not see where it can do any harm to look at the air filter during the regular oil change. That is what I do.

If the little gauge shows anything but green and you have a engine brake I would suggest looking at the filter ASAP. If it is restricting flow and you are engine braking on a long steep hill you risk sucking the filter element into the turbo. When accelerating the blocked flow will limit the rpms of diesel thus the air flow but when engine braking that is not the case.

That spring-loaded gauge can get cr@p in it, introducing friction and causing the gauge to stick.

There's no way I'm going to trust a $2 spring-loaded toy to tell me when the filter is dirty.

coolbreeze01 wrote:
Now I'm curious what the throttle body looks like......Thanks for the pic Bob.

I'm pretty sure it's OK. The top of the filter box and the intake hose were clean. Looks like that clogged up filter was still doing its job.
I do expect to see a jump in mpg - it had dropped off a bit in the last six months.

Now I'm curious what the throttle body looks like......Thanks for the pic Bob.

holy cow... for $15.15 when you buy 6 at a time, start replacing them about every 10k...

http://www.genosgarage.com/FLEETGUARD-AF26106-AIR-FILTER-03-07-59L/productinfo/AF-26106/

Fortunately you are down south, I have collapsed two with snow clogging..

Well, based on your replies - they helped me decide to do what I wanted to anyway :W I did replace the air filter today.
For any of you who have been relying on the gauge - you might want to rethink that. This is what the OEM filter looked like this morning.



That gauge indicator never got more than half way across the green, but I'm surprised that any air at all was getting through the filter - it was that clogged up.

I check mine at each oil change,usually replace every 2nd time.
MoPar fuel and air filters only.161K miles on the clock and running just fine
$25 mopar filters are cheap insurance.
I gotta remember the line about bugs on the tailgate for the next time I see my SIL.:)

91K on that sucker. I think the difference is that GM uses a equipment style air box where as the others do not. I know the 7.3 I had at work ran through air filters like crazy and they came out looking just like the one posted above. That had a direct intake of air off the front. My Duramax has the dust cone things on the bottom and also draws air from the fender well as a posed to the front. Thats why at the track you see missing headlights on the Duramax's, to suck in more air. Oddly enough these intakes are rated at 500RWHP.