i have noticed my radiator hoses are very stiff after driving a bit. it has been doing this for a while now (over a year). my cooling system has always been maintained extremely well. i have never had the gauge over 100c and the coolant is very clean. it doesn't lose coolant either it's just seems after a drive there is a lot of pressure. when i release the cap, it only smells sweet like antifreeze. i have the cap marked "100" and im guessing it is original if not, it's at least 15 years old. the springs seems very strong. i'm about to get a lower pressure cap because i don't want to blow something up like the rad tank or a heater hose. what are the symptoms of a blown HG or cracked head on these engines? I really hope that this is maybe normal. I have put lots of miles on like this driving quite hard and it hasn't gotten worse. the pressure goes away after the engine cools down. what do you think?

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83 300CD- sanden, dual p/f condensers, 160a alternator, ect
91 300TD- 722.6, #22 head, 3.5L IP, w140 manifolds, ect