Getting back to anyone who cares, regarding the CAT #8N-2694 and the CAT #1W-0613 (both listed as "indicator" in the CAT parts system and both supposedly measuring the same thing), and filters I have tested them with, it appears that the latter part number is somehow much more sensitive than the former - or it was defective, I'm not sure.
The CAT folks at Southworth-Milton were not able to really determine what the difference was between these things in the time I had to spend at the counter this afternoon, and it now seems academic. With due fairness, they sell CAT parts for CAT applications and I'm sure they thought I was nuts and I think their assessment may be essentially correct
. However, if there was no difference, I believe they would not make and stock 2 separate items.
To see what was up, I installed a low restriction or high-flowing filter (Amsoil 2-stage oiled foam w/ their oil) and read the results with the first (1W-0613) indicator and found these results (instantly moving from green to yellow on a new filter) to be identical to those on the paper filter I got from dieselgeek as I reported earlier on in this thread. BTW, Jim's filter in this test was a Mahle paper filter from Austria. So, somehow the paper filter registered the same airflow restriction on this indicator as the Amsoil foam filter did. Don't ask me how or why.
Now, with the new indicator (the CAT part Pete has suggested (#8N-2694 - installed today), neither filter has measured as clogged, so I believe several things may be gleaned from my trouble, pending peer review:
1) The 1W-0613 registerd both filters as partially clogged (moved from green to yellow the same amount with a clear snow screen on a power run through 4th gear - WOT), which is not a true measure of either filter's level of clogging. The the foam and the paper were both new, and I believe the foam flows better than paper - relying on Amsoil literature and Greg's recent testing. So, this CAT part was either defective or was being used in the wrong application (Maybe it is for a lawn mower?).
2) I found it odd that the paper and foam measured similarly on the suck-o-mometer. While I admit the results are not controlled and scientifically valid, the indicator did register on the verge of red before I cleaned the snow screen, so it was not "sticking" in the yellow range - and I could pull it to the full red range with manual suction. I guess I have no idea what this data means.
3) I've decided if it is possible for me to buy the wrong part # and install it, I will consistently screw it up. I saw Pete's installation of a kewl gadget at the TDIfest and bought mine before Pete had posted what I believe to be the correct part # in this thread.
4) I paid $21.51 for my 8N-2694, so CAT prices vary quite a bit by region.
5) Maybe the sensitive part # works better for our cars? While it measures an initial restriction (incorrectly), it detects a partial buildup on the snowscreen quite well, and may measure minute levels of filter restriction sooner than the other one(?) Only Caterpillar HQ knows for sure, I guess.
Who knows? My CAT dealer is not as interested in the details of the differences as I am, and I am not sure I can blame them. Time will tell if Pete's (and others) filters clogs up on them and the progression is properly indicated on the gauge, as I suspect has been and will be the case.
Wait and see?
Prior to changing my air box filter (Mahle paper), my indicator read 25 "H20, just shy of "red". after reset and a drive, reading was at 25. snorkel and snow screen were cleaned prior to a recent long drive, but i should check those items again.