Originally Posted by theclencher
Really? Say you have a hot engine- take the radiator cap off and run it- see the coolant shooting into the radiator? Shut it off- see the coolant not shooting into the radiator any more? I think it would act the same if the heater circulation was stopped.
How do you do a harsh enough flush to affect the water pump seal?
Ok how to explain this.
Have you ever heated something up in a microwave and noticed the lid has either popped off the container or is bulging a lot? This is pressure. Then you pull it out and set it on the counter and the lid then pulls down as the food and moisture cools? This is a basic vacuum.
As the water heats in the water jacket in a car it expands. IE the reason radiator caps have a psi rating. As the water is cooled in the radiator it goes into a vacuum if you will. So when the thermostat opens were does the water want to go? Twords the cool vacuum. Also if you ever take a radiator cap off at the wrong time you will get burnt bad due to the psi. The thermostat can be closed say just after the hot water got in the radiator. If you have a 12 psi radiator cap and 10 psi in the radiator,, guess what you just got burnt. If the water has had a minute to cool nothing will happen when you take the cap off. You might even see the fluid level rise a slight amount. The water pump will help some no doubt. But basic psychics rule the roost on this one.
The water pumps real reason for being is circ'ing the heater core. The heating system is on the high side if you will. The pump creates differential pressure to move water thru the heater core. We know there is pressure drop across the heater core. So enough psi has to be made to flow the core. If you shut the motor off the core cools with air being blown over it. No pump no flow. With equal static psi on both sides of the coil.
As for the water pump seal and flushing the system. If you have a cooling system full of dirt and other stuff. You have major problems. Dirt is the number on killer of mechanical seals and lip seals. The other killer is no water. Dirt eats up the sealing surfaces and a seal will fail fast. Running one dry will ruin it also. The water is what makes the seal and it also cools the seal surfaces. If a seal is ran dry what water is in the sealing surface will boil making these tiny explosions between the seal surfaces and causing pitting. Soon as you have pitting from over heating or running dry the seal surfaces or scratchs from dirt. The water tension will not make the seal and psi will force the water out between the sealing surfaces.
Standard materials for mechanical seal are buna or viton for the elastimers with carbon type material and either a ceramic or durametalic matrial for the sealing surfaces. Tis goes for full face seals or lip seals. Most of these basic seals have a max temp rating of 220 degrees F. Most of these seals have a max psi rating from 125 psi to 175 psi in basic config's.
I hope this helps.