Water pump issue

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Joined
Jul 6, 2015
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Location
Iowa
My Car
1973 Mustang Grande 351C 2v
Went for a cruise yesterday. Pulled into gas station and as I was pulling I started spraying coolant. It was coming from the front of the water pump below the pulley. It was spraying out. I filled rad back up at the parking lot and drove about a mile down the road and stopped to check. It was spraying out again. I let it sit for about 25 min and filled it up again. Then drove it home very gently about 8 miles. Pulled in garage and it wasn’t leaking and radiator was still full. Car never got above 190. It is a flowkooler 1648 that was purchased in Dec 2022. Any ideas?
 
It sounds like a shaft seal failure. However, it's self healing ability is beyond my understanding. WAG is stuck, then un-stuck thermostat. Chuck
 
Be sure to check the heater hoses, and especially the bypasws hose. Those bypass hoses are very rarely chaged unless they begin to leak because they can be a real PITA to change. It is possible yours is leaking and shooting its stream into the rear of the water pump pulley. IMHO, the heater and bypass hoses ought to be changed any time the radiator hoses are changed. Do not rule out a water pump front shaft seal failure. That is the more likely point of leakage. You may need to get a cooling system pressure tester hooked up to introduce the pressure needed to verify where the leak is coming from. Many parts stores rent or loan them if you don't have one.

While performing the repairs needed I suggest using a premixed coolant, as opposed to coolant xconcentrate you add water ot, unless you use distilled water. The reason is most tao water is hard water with a lot od dissolved mineral content. If you use tap water to cut the concentrate coolant you will likely end up with a build-up of scaking and other deposits in the radiator. The premixed uses treated water that has no such mineral content dissolved in it.
 
It sounds like a shaft seal failure. However, it's self healing ability is beyond my understanding. WAG is stuck, then un-stuck thermostat. Chuck
Our hot tub pump always leaks at the beginning of the year when we start it after the winter. It leaks for a week and then no more for the rest of the year. I know the shaft seal is going but it has been like that for 4 years so I will leave it in place until it dies. That said, maybe the coolant builds up residue or something through an imperfection on the seal that eventually "seals" up again.
 
I contacted Summit this morning about the water pump as the manufacturers warranty is 2 yrs. They are sending a new one and have sent a return label for me to send mine back. I will be pulling the water pump tonight after work and post what I find with my inspection. I was wondering if running a 19 PSI radiator cap may have attributed to the premature failure? Any thoughts on this?
 
Got the pump pulled last night, wasn't too bad. About 1/2 hour and it was out. It was for sure spraying out the lower weep hole as you could see the spray marks clearly since I am running the Blue Japanese Antifreeze and that **** makes a hell of a mess. Replacement from Summit is on it's way.
 
I contacted Summit this morning about the water pump as the manufacturers warranty is 2 yrs. They are sending a new one and have sent a return label for me to send mine back. I will be pulling the water pump tonight after work and post what I find with my inspection. I was wondering if running a 19 PSI radiator cap may have attributed to the premature failure? Any thoughts on this?
Why the 19 PSI cap? Chuck
 

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