Pump pulsating on cold water only.. Older Hawk HC500

[Scottyk]

Hey guys, I have been fighting a small pulsation problem in 1 of my self serve bays for a week or 2 now. The rundown here is that the pump is a Hawk brand HC500 which I believe is similar to a hotsy pump. It is belt drive running about 980rpm, 1400psi thru a 05 tip with hot water, less when its cold water. The cold water rinse is softened city water pressure going thru a single in/out solenoid. Hot water soap and wax is in a holding tank and chemicals sucked into low pressure side with a check valve going into the pump inlet. I have unhooked the water inlet and it flows alot of water when not connected to the pump so I do not believe it is a water flow issue. I have taken the solenoid apart to look for junk while I was at it. I have replaced all 6 check valves but have not removed the manifold yet. That did not effect it at all. The strange thing the pulsation seems to be getting worse with more use and when I switch from cold to hot the pressure will climb and the pulsation SLOWLY goes away but doesnt go away completely. Takes about 45seconds-1 minute for it to do this.

Do you think the temperature of the water could be swelling up seals and covering up the problem or??

Thanks and sorry for the long story I just wanted to cover most questions.

 

[Scottyk]

Dont everyone reply at once now!! lol

I just wanted to update this thread just in case someone might find it useful, but in my quest for information I have found nobody has really heard of Hawk Pumps. but here is what I found out.

Hawk and Hotsy pumps seem to use the parts, Im not sure if they are made by the same company or what the deal is.

My pulsing problem was due to a piston seal that was missing a piece around the OD, like it was broken somehow, the seal is some sort of plastic material, almost like a woven plastic. I have no clue where the missing piece went but all functions are working ok. I also replaced the unloader "regulator" with a new kleenrite unit. Now this pump is putting out 1500psi+ easily where before it was topping out at 1200psi this is done with a 1505 nozzle.

These pumps are made in italy and seem to be nice high quality units.

Thats all I have

 

[2Biz]

The pump you have is not very common. That's probably the reason you didn't get any responses? Most operators here on the forum either uses Arimitsu or Cat...Good to see you got it figured out. Next time it will be piece of cake to fix!

 

[MEP001]

The description of the seal and the part about them being made in Italy makes me think it's a relative of General Pump.