Ok, but now that you have added lots of water, and it is a diesel engine, especially a navistar, you best very quickly drain the water out and put new approved antifreeze in. If any rusty stuff comes out when you drain it, flush the system and reinstall new antifreese. It is essential that you do not run with water only. And also very important that you maintain the coolant properly.
When putting in new coolant, mix only with a distilled water. NO WELL WATER.
Here's one great read with pictures. on coolant system electrolysis.
There are thousands of youube videos on the subject. Check some of them out for your information to help eliminate future engine issues with a diesel engine. A diesel engine, especially older ones, do require a more rigorous coolant maintenance program than a gas engine.