According to everything I've read my Cummins ISL400 cooling system has a 15 gallon capacity.
I have flushed it twice now and am planning to do a 50/50 final fill of the same coolant that has been in the system, Rotella ELC.
I have only been able to drain about 10-1/2 gallons of coolant the three times I've tried, and the coolant is not getting significantly paler red in color. Is it possible that because our FT is only 36' that it doesn't have the coolant capacity of 15 gallons?
I probably need to know the answer to my question before I add the ELC concentrate at the rate of 50% coolant capacity.
The coach length would have nothing to do with it. I don't think you can drain all the coolant out of the system. I would allow for the missing 4 1/2 gal by putting in 2 gal of the concentrate, then do the 50-50 mix to top off.
The heater hose length, engine pre-heat and Aqua Hot must all have an effect on the capacity.
Ours is a 36 footer with AH and engine pre-heat.
If it is indeed a 15 gallon system then I need to add 7.5 gallons of concentrate and top off with distilled water.
If it isn't a 15 gallon system then I need to find out what it is and adjust the concentrate amount.
It would have some effect, but and extra 8 ft. of 5/8 heater hose compared to a 40 ft. coach wouldn't hold but a quart.
After your first drain and fill did you run the unit with the heater on high and again with with each flush.
Did you remember to turn on the dash heater to circulate the coolant out of those lines and the heat exchanger? That might account for it.
It will never all come out. Thats why its so important to do multiple flushes and then check concentration with a refractometer after refilling. Use your best guess to get it close to 50/50, run it to get everything well mixed, test and if you arent close to your ideal mix, drain some off and refill with concentrate or water to achieve desired results.
Yup, you will never get it out. Length matters only in additional volume in two 5/8" heater hoses off additional length. Pretty much noise level when talking about 20 gallon system.
If total system capacity is 20 gallons, merely do the last rinse (including dash heater ON) with distilled water. Add 10 gallons of CONCENTRATE, NOT PREDILUTE and just top off with distilled water.
OK guys, thanks.
I did have the heater on for both flushes, and now headed out to get some more distilled water.