[dsraven]

coolant, in general and especially in diesel engines, naturally changes PH levels and should be tested occasionally. auto parts places sell test strips for that purpose. they are simple to use, just dip it in the coolant, wait a minute for the strip to change color, and compare against the side of the bottle graph to see your coolant's PH level. on diesel engines, there are coolant filters and they can be purchased with different levels of PH additive to deliver the correct charge to the system to bring it back to acceptable levels. I have personally seen a GM v6 engine that was driven only, not much for service, and it developed a coolant leak. the coolant ate a hole right through the aluminum water pump. coolant has a lifespan because it goes acidic over time.