The coolant change project is progressing well, though it’s a major time investment. I’m transitioning from Power Cool, which requires SCAs, to an EC-1 spec extended life coolant. Although I’d prefer to use the Detroit Diesel extended life product, it’s only available in a 50/50 mix here in Knoxville, which doesn’t work for me. Instead, I’ll use CAT coolant, which is an OAT (Organic Acid Technology) and meets the industry standard. The pricing is reasonable: concentrate is $21.48 per gallon and pre-mix is $11.55.
I assume the cooling system capacity of 24 gallons is accurate. Besides the engine, my system includes large volumes of coolant in the OTR heat exchangers, the Webasto, and the HW tank. I understand that draining the system completely would require significant disassembly, which I’m not prepared to do.
Currently, I’m draining as much old coolant as possible through the petcock at the base of the radiator or the lowest coolant pipe. Each time, I drain about 15 gallons, leaving around 9 gallons in the system, including the piping, OTR system, HW tank heat exchanger, and transmission intercooler.
To flush out the old Power Cool, I’ve drained and refilled with fresh water four times. At the last drain, the water was nearly clear with just a pink tinge. Since the EC-1 coolant can tolerate up to 10% SCA coolant, I’m planning to fill the system now, but first, I’ll flush the radiator and replace a couple of hoses on the Webasto system. After each drain, I run the Webasto, engine at high idle, and OTR heat system at the highest temperature setting to circulate the fresh water throughout the system.
Replacing the hoses will remove more of the old coolant, so with the next fresh water fill, I’ll have nearly eliminated the old coolant. Each drain and refill have diluted the SCAs in the system, and theoretically, I should have about 2.4 gallons of old coolant mixed in by the time I flush the radiator.
When I flush the radiator, I’ll isolate the bus engine from the rest of the system to avoid contaminating it with the flush chemicals. I plan to flush the radiator at least three or four times to ensure no chemicals remain. Assuming the system retains 9 gallons, I’ll add 9 gallons of concentrate for a 50/50 mix and then top off with 6 gallons of premix.
I’m fortunate to have convenient waste disposal options in Knox County, TN, where I can drop off old coolant, oil, and other waste at no charge. I also have a suitable workspace where I can safely handle the coolant without risking spills or harm to animals.
Overall, the project will cost around $270, and with any luck, I’ll only need to recharge the coolant every three years for the next six years. I’ll apply the same process to the generator soon, so I’ll only need to keep a gallon or two of concentrate on hand for both cooling systems.