Coolant change

[REVY03]

Hello, Have a 2003 Cummins ISC,I have searched for days and can not find anything. I am just trying to replace coolant in engine,there is a tag on engine that says--close heater bypass valves and open petcock on heater valve--I have never seen this mentioned on here.
I can't even find those valves. Any help to do this. It shouldn't be this hard.

Thanks,Mike

[wolfe10]

If you are changing coolant, you definitely want water circulation through the heater core.

For a "blow by blow" of the PROPER way to change coolant:

http://forum.dieselrvclub.org/index.php/topic,6653.0.html

Brett