Priming a March Pump

[Catt22]

You definitely have an air leak somewhere. You should be able to run wide open or anywhere in between without losing prime. You could pressurize the pump and lines with air, CO2 or even water to check for leaks. With air or gas, you could spray everything down with soapy water and look for bubbles. It only takes a tiny leak to cause a problem. I would only dismantle and start over as a last resort. Hose clamps can sometimes be the source of leaks. This is usually due to the hoses softening up when exposed to heat. Check those first.

 

[pickles]

I did a wet run tonight and had no issues priming my Iwaki MD-70RLZ pumps, but when I start to transfer liquid by opening and closing valves I tend to lose prime. I'm guessing this is introducing air into the lines. I also have some slow leaks that could be the culprit. I guess I should chase down the leaks and see where I stand. Its frustrating for sure!

 

[EarthBound]

The March seems to like it best if there's at least some restriction on the output side - I keep the output ball valve 1/2 to 3/4 closed now.

Thank you so much. I received instant gratification and a HUGE sigh of relief.

 

[EarthBound]

Lonnie and Bobby don't use the bleeder valves when priming their pumps. Why and how?

 

[Tiber_Brew]

Make sure you have the Pump OUT facing up. If you don't have that then you're not going to flood the pump with fluid and it won't pump. Also, make sure if you have a valve on the output that it's open while priming so that air won't be trapped inside the pump.

FWIW, this is not necessary, but can help certain setups. Both of my March pumps are mounted horizontally, and don't have issues with priming. If at first you have problems with air, I'd go ahead and give that a shot; it's worked for many people (it just wasn't necessary for my setup).

TB

 

[Sawdustguy]

Here is a solution that works every time without operator intervention: