There is quite a bit of discussion in the archives about the 617 running a bit warm in the summer months. Many folks with perfect cooling systems can maintain temperatures that are close to 90°C. even when it's 95°F. outside.

But, others will observe the temperature climb close to 100°C. under these conditions. My SD is in this category.

Please understand that there will never be any damage done to your engine if you run it at 100-105°C. all the time. That red zone on the gauge is above 120°C. That's the point where you should turn on the defroster and slow the vehicle down. You won't hurt the head or the block at any temperature below 120°C.

This presumes, of course, that the cooling system is filled with coolant and that it is holding pressure.

There are several members who have done the same thing as you have done and replaced all the components of the system other than the radiator. But, in the end, it's the radiator that is usually the culprit. As they get older, they simply can't dissipate the heat as well as they could when new. This is especially true if the old coolant has not been changed on a proper schedule.

So, rest assured that you won't have any problems with the vehicle if you operate it with the temperature gauge at 105°C. If it goes above this value on a regular basis, consider replacing the radiator.