Does a water pump need to be primed?

[woodie49]

Before I reassembled my engine, I put the pump and housing back on without the water distribution tube in and reverse flushed the block. I drained the block and pulled off the pump and put the WDT in (not so easy as I expected), installed the water pump and thermostat.

I filled the radiator with two gallons of 50/50 collant/water and that was to the top. I fired the engine up tonight and let it go to about 180 degrees. I just put in a 160 degree thermostat. The water in the radiator has moved down about an inch and it has gotten warm (but not really hot) and it does not appear to have cycled through the block.

I am expecting to put another two gallons of water in when the thermostat opens, but nothing has happened yet. I didn't want to go above 180, and the car did not appear to be heading there anyway, seemed to be holding that temp.

I drained the block after the reverse flush. It should take 15 to 16 quarts. I have put only half that in, and I haven't seen this cycle when the thermostat opens.

Is it necessary to somehow prime the water pump?

Could I have installed the thermostat backwards, I put it in big side down. I am getting a little worried.

Any ideas?

[greg g]

no gravity will do its best to fill the system. Since the top of the radiator is above the engine, the system will take care of filling. Unlike todays casr with the radiators at or below the level of the engine, these systems don't need a burp. They can be over filled and will puke out coolant they don't need. So it's best to leave about 2 inches of so of air in the top of the radiator. Run the car to normal temp then check the level.

[chopt50wgn]

When you refill a system from the radiator, you must look for an air bubble stuck in the motor. The way you know you have one is the motor will get hot real fast. The only way to get the bubble out is to cycle the motor.........let it get hot, cool down , get hot cool down.Doing that a few times should move the bubble.

And no, you don't have to prime a water pump.

[Don Coatney]

Could I have installed the thermostat backwards, I put it in big side down. I am getting a little worried.

Any ideas?

Explain big side? The spring always goes in the block (head in the case of a flathead Mopar).

Once up to temperature with the radiator cap removed and the engine running at a high idle you should be able to see water movement using a flashlight looking in the radiator fill neck.

[woodie49]

Explain big side? The spring always goes in the block (head in the case of a flathead Mopar).

Once up to temperature with the radiator cap removed and the engine running at a high idle you should be able to see water movement using a flashlight looking in the radiator fill neck.

Spring side in the block. That is what I thought.

[greg g]

did yo put the thermostat in a pan of boiling water to see if it was actually opening?

[woodie49]

did yo put the thermostat in a pan of boiling water to see if it was actually opening?

It was new, I just pulled it out of the box and put it in. I gotta beleive they are almost never, ever bad out of the box.

It looks like everything is good with the cooling system. I think it just was not getting hot enough to exchange the water between the block and the radiator. But, given the issues I thought I was having, I did wish I had tested it before I installed it. Also wished, at the time, I had flow tested the rebuilt radiator. Simple things to do at the right time and really provides some piece of mind.

Thanks for your help, I actually was thinking that, at some point fairly quickly in the process, a large amount of water would drain from the radiator and fill the block, and I had my other two gallon containers of fluid ready to pour into the radiator to fill to capacity. I really like working on this car, but I am not very good at it. Always a learning experience.