Newbie question about Dodge Durango

[David1970]

Heres the problem. 2000 Durango, 5.9. Started overheating and not getting heat from the heater. Already changed a lower radiator hose, thermostat, and radiator cap. The old cap was rated 3 lbs psi over the the recommended cap. Now, the coolant res stays full the whole time even after the motor gets hot. Here is my dumb question.... With the rez already full, how far should I fill it from the radiator cap to keep from over filling the system? On older cars you can fill it till it tops off. That is with the cap on the radiator itself. Since the cap is on the hose I wasnt sure if I should fill it the same way, till it tops off on the hose. Dodge has really stumped me on this set up. I have already flushed the system and in the process of filling the system back up. The old thermostat had a ton of silicon used for a gasket so flushing seemed a safe bet as a precaution. Rez is full, just dont know where to stop filling at the cap. Ive been told by a dodge mechanic that the rez always stays full hot or cold.

I dont like reading all the stuff about Durangos overheating. Seems to be a normal issue with this vehicle it seems. Ive been fighting with overheating for days now and hoping this fixes the problem. Water pump seems solid which Im glad for that. Changing it on this model looks to be a royal pain.