Why did my motor freeze until I let cool water flow through pump for a while

Common problem is water pump impeller is bad. Should be checked every spring. When water pump isn't providing enough water to cool motor, thermocouple in motor will stop motor to avoid damage. When motor cools, it will restart and run until it overheats again.

The most common causes of a water cooled engine overheating are (1) poor circulation of cooling fluid (bad water pump or stopped up radiator); or (2) inadequate air flow cooling (bad cooling fan); or (3) compression gases entering the cooling system (leaking head gasket or cracked block or head). The first check is to see if air is in the cooling fluid (small bubbles appearing in top of radiator or coolant reserve tank). If so, then #3 is the problem. The second check is to see if the cooling fan (s) is running properly (can feel air flow on output side?). If not check wiring and/or replace fan (#2). The last step is to drain the radiator and engine (turn over engine to allow water pump to empty the block). If additional cooling fluid does not drain out the radiator drain port, the water pump is defective. If the water pump does empty the block, then flush the system with a good flushing agent. Follow instructions on flushing agent bottle. Drain out the flushing agent and re-fill radiator and block with clear water. Run engine as per instructions on flush agent bottle. Drain system again and re-fill with antifreeze (50%) and water (50%). If vehicle is located in a very cold climate, then increase the antifreeze % up to 75% (25% water). Remember, not only does antifreeze help to keep water from freezing, but it also helps to increase cooling ability.

CM3 Operational Sequence.
From Off, push and release the freeze button.
1. If sump is full,water pump starts.If sump is not full,water valve opens to fill it.
2. Compressor starts when sump is full.Air cooled fan motor starts too.
3. water pump stops early in freeze cycle for 30 seconds.
4. Sump refills after pump starts.
5. In low ambient condition,fan motor may begin to cycle on and off.
6. Freeze continues until water level in sump drops to preset point. Exceptions: SCE275 must fill sump two more times.
7. Fan may shut off before the end of freeze.
8. Harvest begins. Hot gas valve opens,pump stops.
9. Pump restarts, inlet water valve opens to fill and overflow the reservoir.
10. Harvest continues for preset first cycle harvest time.
11. If bin is not full, cycle repeats ( compressor stays on). If bin is full, unit shuts off at the end of harvest.
OK with that out of the way unless you unplugged any wires cleaning the machine should not have caused any problems. First cut off water and pull water supply line from water inlet valve look in the end of valve there is a screen in there it could be stopped up. If the valve screen is not stopped up then put supply water line back on and turn water back on. power the CM3 controller off. push freeze button. now with a voltage meter check at the water inlet valve to make sure you are getting power to the valve.If you are then either valve is stopped up or valve is bad. If you are not getting power to valve then replace the CM3 controller now make sure the bin full light is not on because if it is this will not let controller go back to a freeze cycle.

Could be overheating and tripping the internal thermistor, once it trips it won't re-start until it cools off and the thermistor resets. Try using a portable fan to cool it down, it may be enough to do the trick. Also make sure all the cooling slots/holes in the case are clear to allow properp air flow.

Hello! The heater core is partially blocked...I would suggest flushing the cooling system with the temperature control on high...NOTE...The type of anti-freeze used in your vehicle is DexCool...If another type is used it may damage the cooling system...To flush...Drain radiator...Fill with plain water...Run engine until thermostat opens...Turn engine off...Let cool then drain...Do this at least three times or until water drains clear...Install new thermostat...Refill with 50/50 DexCool...Leave the radiator cap off as engine warms...Allow all air bubbles to escape...Then install cap...

The down side of DexCool is electrolysis...Electrical current flowing in the cooling system which can cause the anti-freeze to "clump" blocking its flow...Periodic flushing eliminates the problem...

Guru.........Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

WATER PUMP FAILURE COULD BE CAUSED BY WRONG COOLANT USE DEX COOL ANTI FREEZE.REPLACE THERMOSTAT AND BOTH RADIATOR HOSES TOP HOSE AND BOTTOM HOSE.SOFT HOSES COLAPSE LIKE PUMP HOSE.IT WILL COLAPSE FROM PUMP VACUUM CLOSING OFF SOME COOLANT FLOW.MAKE THE HEATER CORE NOT STOPPED UP IF SO IT WILL RESTRICT WATER PUMP BYPASS CAUSE EARLY PUMP FAILURE.YOU NEED 50/50 COOLANT MIXTURE YOU HALF WATER AND HALF DEX COOL DONT USE GREEN ANTI FREEZE USE ORANGE DEX COOL.I HAVE 3.4L ENGINE AND 3.1L ENGINE BEEN USING DEX COOL ANTI FREEZE SINCE I HAD BOTH VECHICLES. HAD NO WATER PUMP PROBLEMS.

bad low coolant switch or still low on coolant.

Engine Cooling The cooling system components are the:

• engine coolant temperature sensor (ECT sensor) (12A648)
• radiator (8005)
• degas bottle (8A080)
• radiator draincock (8115)
• water pump (8501)
• water temperature indicator sender unit (10884)
• water thermostat (8575)
• dual speed fan motor assembly

The water pump circulates the coolant.
The water thermostat:

• controls the engine coolant temperature.
• allows quicker engine warm-up.

The degas bottle:

• provides a location for fill.
• contains coolant expansion and system pressurization.
• provides air separation during operation.
• replenishes the engine coolant to the system.

The fan motor (8C607):

• operates only when the ignition switch is in the RUN position.
• will not operate with the switch in the OFF position.

The engine coolant flows:

• from the lower radiator hose (8286) to the water pump.
• from the water pump to the engine block and the cylinder heads.

A closed water thermostat returns the engine coolant to the water pump; an open water thermostat allows the engine coolant to flow to the radiator.
Engine coolant provides freeze protection, boil protection, cooling efficiency and corrosion protection to the engine and cooling components. In order to obtain these protections, the engine coolant must be maintained at the correct concentration and fluid level in the degas bottle.
When adding engine coolant, use a 50/50 mixture of clean, drinkable water and engine coolant.
To maintain the integrity of the coolant and the cooling system:

First off, when the fans are both running, the compressor should also be running. Sometimes, because they run quietly, it is difficult to tell if they are running. Touch the compressor to feel for heat and / or vibration to confirm running. (if the compressor gets too hot, the overload will stop it until the compressor cools down. That could happen with too low or too high voltage, even with the cooling fan running) You did not say how long you let the unit defrost. To properly defrost it, you should empty out the freezer side, remove the shelves, and take the metal cover off the back inside wall of the freezer. Then, use a hair dryer to melt all the frost off. If the coils were blocked with frost, you probably have a burnt out defrost heater (located at the bottom of the cooling coils) when replacing the defrost heater, use part number WR51X10101 and follow directions, as it may have a different configuration than the original heater. A frost blocked evaporator (coils inside the freezer) will stop normal air circulation inside the refrigerator. Cold air will then be able to flow backward, into the bottom of the refrigerator side through the normal return air duct located at the bottom of the refrig / freezer divider. This cold air can freeze the water line or water reservoir located there. There for, solving your defrost issue most likely will also solve your water line freeze issue.

The thermostat might be stuck open. If it is then water running into the radiator is not spending enough time there to cool off before flowing back to the engine block. At speed the increased airflow is having a greater cooling effect while blowing through the radiator fins. With the car totally cool, open the radiator cap and then start the car. Watch the water flow in the radiator. If it is flowing straight through right from the start, you'll know it is the thermostat. It should sit in the radiator until the engine reaches opening temperature and then the flow begins. As soon as the cool water from the radiator reaches the thermostat, it closes and the flow stops. So constant flow equals bad thermostat, flow then stop then flow equals working properly.

Check the back wall of the freezer for ice buildup.
If yes, a defrost parts problem.
Check the freezer fan. Is it running?
If no, replace the freezer fan.
Check the condenser fan at the compressor. Is it running?
If no, is compressor hot?
If compressor is hot replace condenser fan motor.
If compressor is not hot.
Replace the compressor start relay.