It used to be accepted that a motor that ran between 190* and 210* was OK so long as the cruiseing was on the lower side, modern engines as stated run warmer. Motors with poor flow do develop hot pockets that is why many engine builders drill and fit a water connection at the back of the inlet manifold and plumb up to either a modified thermostat housing or the radiator itself, there is also a modification where water is taken out of the rear of the heads and I have seen water fittings coming out of welsh plug holes. Remember that the water pump is at the front and so is the inlet & outlet so the rear of the motor gets a lot less direct flow. The cooling system is not just a matter of bolting on a water pump and forgetting, there are modifications that can be done to reduce the gap at the back of the impeller and make the flow more positive. Some cheaper pumps have bad clearances and are little more than agitators, as the coolant heats up it expands building up pressure, the rad cap holds the pressure raising the boiling point of the coolant, that is why when the motor is shut down there is still pressure in the system until the motor cools down. The radiator cap can leak or start to open at a lower pressure over time, I always test a cap before fitting, cheaper caps have been known to hold very little pressure.
Topic: What are the Pro's and Con's of running a thermostat? (Read 5258 times)
