I recently had an unusual experience with filter plugging on a diesel fuel filter in an agricultural combine. The combine plugged six filters in the previous 350 hours of operation. Because this was obviously abnormal and filter plugging is not rocket science, I decided to investigate. I removed the can from the filter to see what was causing the plug. To my surprise, the filter media and the small residue of fuel left in the filter looked perfect.
I called the filter manufacturer (this was not an off-brand filter) to ask what could cause perfect-looking filter media to plug. The manufacturer’s representative asked me for the lot number stamped on the bottom of the filter. When I gave it to him, he disclosed that the company had a manufacturing problem at the end of 2002 and beginning of 2003, which was causing some filters to lose their seals between the O-rings and plastic stand-pipes. These filters would suck air and act as if they were plugged. When a faulty filter was replaced with a new one (from the same lot), the new filter would work fine for a while and then it would lose its seal and suck air again.
It is easy to blame the fluid when you are having a filter plugging problem. This experience proves, however, that it is worthwhile to cut open the can and inspect the filter media. Filter cutters to open spin-on filters can be purchased from auto parts stores for around $40. They are easy to use - simply clamp the filter into a vise and with two or three revolutions of the cutter, the top comes off the filter can with no debris. Your discovery may surprise you.
Submitted by Blaine Ballentine Central Petroleum Co.