Beer Forum

I have been using my March pump in addition to my B3 gravity tower for more than 3 years. The last couple brews I have noticed that the pump with lose prime. You can tell by the pump ramping up speed and the liquid stops. So far I have changed the O rings and made sure the impeller is clean.

Any thoughts? It do not see any leaks, etc. The pump will always get prime and start right up. Then 15 sec later..nothing

The only thing I can think of is if you are pumping boiling or near boiling water or wort. The low pressure inside the volute can cause the liquid to flash to steam. I've had them make terrible noise under these circumstances but never actually had one lose prime. I guess I'd take the cover off the volute to make sure that the impeller has all its leaves.

Interesting thought. The pump has all the "fans" intact.

I have to be careful with turning my pump on full speed with my boilermaker. It actual sucks the bottom of the pot up to the dip tube and stops flowing. Not a problem on any of my other pots.

bluelou6 wrote:I have to be careful with turning my pump on full speed with my boilermaker. It actual sucks the bottom of the pot up to the dip tube and stops flowing. Not a problem on any of my other pots.

Silver solder a little nub of SST (or even copper wire) to the end of your dip tube.

As for the OP:
I'm thinking autoneuclation from, as mentioned, the heat.
Example
In your microwave heat water in a pyrex vessel till it boils strongly. Open the door and observe the boiling stop. Sprinkle a bit of salt into the water. Watch it boil furiously for a bit and be glad I didn't tell you to grab it.
All that is happening is the liquid on the edge of boiling is stimulated just that tiny bit and that is sufficient to cause molecular action which heats the water just enough to get a fast boil. It's called autoneuclation.

Jiggling it can do it to.

In the lab people cooking Agar often forget or fail to understand this and get boiling hot sticky agar all over their skin when they reach in too soon after the timer goes off to grab their agar.


So what I think may be happening in your Brewery:
The wort fluid is hot hot hot as it flows from the tube from the BK.
It hits the pump.
The pump agitates it and suddenly it's boiling again.
The steam from the boil blocks the tube from the BK and the bubble has to clear before the pump can pump again because the March pump can not self prime, it needs a gravity flow.

Take your pump apart and make sure the teflon thrust washer is there between the impeller and front housing. Will be either a white or black washer. Also make sure the impeller is not sticking/binding to the shaft due to sugar buildup. You can wipe it off with some denatured alcohol....if it continues to happen you may have overly tight clearences between the shaft and the impeller and in that case you can take a 17/64" drill bit and ream the impeller bore out slightly bigger. Hope that helps.

-Walter

thanks everyone. This week I am going to do a water test run with my new camp locks and see if I can locate the problem. A lot better than in the middle of a double batch of beer