Why do you believe this is a problem? The engine certainly doesn't care about a temperature of 100°C. In fact, depending on the gauge, that's about the point where the thermostat is fully open.

The point to get concerned is when the temperature climbs above 105°C. and that point will only signify that you should start looking for the problem. The engine will operate at 105°C. all day long and never give you a hint of trouble.

Many folks are overly concerned with this engine running at these temperatures. However, the problem with the engine is when that needle heads over 120°C. which typically occurs when the water pump goes south or when the engine is low on coolant.