Filter Cleaner System Passes Test In St. Louis Bus Fleet.

Bi-State Development Agency, St. Louis, Mo., is the mass transit provider for the St. Louis metropolitan area. The agency operates more than 650 diesel-powered vehicles in daily revenue service, running in excess of 25 million miles each year.

Among the many operational issues the fleet has had to deal with are those concerning the cooling systems in its vehicles. Typical problems encountered have included solder bloom and silica gel dropout and the effects of excessive usage of antifreeze. These led to labor-intensive cooling system cleaning procedures and downtime and progressive damage from various cooling system failures.

In 1992, Bi-State began testing the Enviro-Cool coolant cleaner filter to address several of those problems, according to Lyle Howard, manager of product development at the agency. The Enviro-Cool system, developed by Enviro-Cool Inc., St. Charles, Mo., is designed to clean engine cooling systems and allow significantly extended intervals between coolant system drain and changeout.

In operation, first use test strips are used to determine if the inhibitor and coolant level is correct. Then the Enviro-Cool spin-on cleaning filter is installed in place of the conventional filter. The vehicle is then returned to service for a period of two to four weeks, during which time, the filter cleans the system. The cleaning filter is then removed and after the cooling system is checked for the proper level of dissolved solids, the conventional inhibitor filter is re-installed.

By using the cleaner filter once a year, Enviro-Cool said that vehicle operators can go as long as five years between cooling system drains.

Prior to the test, data was collected and reviewed on the buses selected for the test to ensure a more accurate analysis of conditions before and after the introduction of the Enviro-Cool coolant cleaner filter.

According to Howard, at that time, the cooling system maintenance and cleaning consisted of maintaining the supplemental coolant additives (SCA) through the use of inhibitor filters, pre-charging the SCAs in liquid form and monitoring the total dissolved solids (TDS) every 12,000 miles. When the TDS reached 2000, the system was drained, refilled with water and a cleaning product, run in the shop to circulate the cleaning product, then drained again and refilled with new anti-freeze. The SCAs were precharged in liquid form, and a new inhibitor filter was installed.