When I removed the heater coolant loop I found two very bad things:
- It was green.
- It had gunk in it, likely small amounts of settled oil.
Now. Why is it being green bad you ask? It is because the DT466, while a magnificent engine, is prone to various issues if one uses improper fluids or simply doesn’t change them out when scheduled. Green antifreeze is /not/ what makes the engine happy. Green antifreeze is what makes the sleeves eat through rapidly due to cavitation.
The second problem, the gunk? Yeah, fairly obvious do-not-want issue. 😛
Worst case was I have to do a rebuild, looks more likely that will be the case. Roughly $1100 and I get to basically start new on engine wear. Not a bad deal.