How to Identify Cummins ISX15 Water Pumps: 4 Common Types Compared

The Cummins ISX15 engine is a workhorse, but maintenance can be tricky when it comes to the cooling system. There are at least four common water pump variations (3684449, 4089908, 4089909, 4089911) that look similar but have critical differences in housing and pulley design. In this guide, I will show you how to distinguish them to avoid installation errors.

Correctly Understanding the Differences in Cummins ISX15 Water Pumps

CUMMINS ISX15 water pump 3684449 is the most distinct model. You can identify it by looking at the Water Pump Volute Housing. It features a completely unique casting shape compared to other models.

These two CUMMINS ISX15 water pump look similar but check the housing structure:

1. 4089908: Features a one-piece integrated Volute Housing (Solid casting).
2. 4089909: Features a two-piece split-type Volute Housing.

CUMMINS ISX15 water pump 4089911 and 4089909 are often confused. However, the 4089911 has a larger pulley diameter. Always measure the pulley before fitting to avoid belt tension issues.