Coolant Filters

Engine Coolant Filters

Coolant filtration provides benefits, even when used in coolants that do not require routine additive supplements.

For many years a majority of medium and heavy duty trucks have been equipped with cooling system filters. These filters are plumbed in a bypass coolant line, not in a full-flow line as are fuel and lube-oil filters.

In addition to providing a moderately coarse filtration function, these filters have been used as a convenient way to deliver vital supplemental coolant additives to the coolant, extending its life and optimizing the protection that the coolant is providing to the engine and other system components.

For several years, in addition to standard filters intended to be changed every 20,000 miles or so, extended service filters have been available. These filters are engineered to remain in service for a year or more, and up to 150,000 miles. They use various technologies to maintain coolant for that period of time, minimizing the attention required by fleet maintenance personnel, and further providing on-board protection while the vehicle is away from its service shop.

The introduction of extended life coolants has led to the omission of coolant filters from some new trucks. On the surface, this appears logical, but recent studies of filters retrieved from engines operating on various kinds of coolants have found that the filters are collecting a lot of particulates and a variety of deposits.

It appears that cooling systems benefit from filters, even when they are not required, or being used, to deliver supplemental coolant additives.