overheating

[Phil]

I just finished a rebuild on my CJ-3B's engine and now it overheats. The thermostat is 160 degree and checks good. I took the radiator to the local radiator shop and they said the flow is excellent. I thought about trapped air in the system so I filled the engine block with antifreeze though the thermostat housing before I install the thermostat and then filled the radiator. When I remover the radiator cap I don't see any of the antifreeze moving. By the looks of it I would say that the water pump is bad but it's a brand new one. Has anyone had any issues with the new water pumps? This isn't the first Jeep engine I have rebuilt but I never had an overheating problem. Thanks

[SteveKfl]

Have you pulled the coil wire, and pulled a heater hose-plug, or a hose, and turned the engine over, by starter only, catching the potential flow from the pump?

[Phil]

Have you pulled the coil wire, and pulled a heater hose-plug, or a hose, and turned the engine over, by starter only, catching the potential flow from the pump?

No but I try that today, Thanks

[Rus Curtis]

Phil,
How did you confirm the thermostat was working?  I installed a brand new one in mine and it was stuck solid.  I also added the hole in the thermostat webbing that will help with trapped air (some already have it).

Running the engine without a thermostat will tell you if the pump is working.

[Phil]

Phil,
How did you confirm the thermostat was working?  I installed a brand new one in mine and it was stuck solid.  I also added the hole in the thermostat webbing that will help with trapped air (some already have it).

Running the engine without a thermostat will tell you if the pump is working.

I have tried two thermostats, one 160 degree and one 180. I checked them both by putting then in hot water to make sure they opened up and they did. I did try it without a thermostat and it still overheats just not as fast. If I rev the engine up it does cool down some but not to where the temp should be, it's still hot. I never had an overheating issue with this engine before the rebuild but the block was on an engine stand for a couple of month before I got it back together again. I thought maybe the mice got into it so I bore scoped as much as the water jacket as I could and found a couple kernels of corn they found somewhere, maybe they packed more somewhere I can't see and it's blocking the flow.

[Rus Curtis]

Well,  it sounds like you're on the right track on the thermostat.  I would've leaned in the direction of the water pump until you mentioned your water passages had corn in it.  I don't know for sure but think it might be a stretch to assume nest building inside an engine on a stand.  I suspect you're not wanting to strip it down all over again for an acid bath. 

The only other thing I could think of is reverse pressure flow.