Chem-Tech makes thumping noise

[lwparchive]

I have a chem-tec 100 220 volt pump that injects clorine into my water system. The pump makes a thumping noise when it starts.

When I open the bleed valve the noise stops The pump is 20 years old.

Do you know what would cause the thumping noise?

Would it be more cost effective to replace or repaire the pump?

Thanks for your help.

George M

[dcohan]

AFTER 20 YEARS I WOULD REPLACE THE PUMP. CHEMICAL FEED PUMPS HAVE A 5-7 YEAR LIFE SPAN