Pump / Motor slowing down, speeding up ?

[softsuds]

I have 5hp Toshiba 3 phase motors running CAT 530 Pumps. I have one bay that will slow down then speed back up randomly when someone is using it. Sounds like its bogging down and going to stop then it speeds back up. Is this a sign of a motor going bad ? I have turned everything by hand and it spins freely, pump has oil, doesn't get hot. ?????
The motors and pumps are about 23 years old but still, for that motor and that pump, 1200 PSI in a SS wash hasn't been alot of real work for them

thanks

-Brandon

 

[soapy]

Sounds like you may be starving the pump for water or sucking air in somewhere. These will cause a surging sound.

 

[Ghetto Wash]

Make sure the belts are tight. If the belts are loose, when someone lets go of the trigger the belts will slip and sometimes not squeel so you can't readily tell. The motor still spins the same speed, but the pump will slow down. When they pull the trigger again, the pump will run at normal speed again.

 

[PaulLovesJamie]

sounds like a water supply issue to me too.

 

[MEP001]

Ghetto is probably right, your belts are likely loose. 3-phase motors aren't going to slow down and bog and not overheat quickly.

 

[bigleo48]

I vote check belt.

 

[softsuds]

Thanks for all the suggestions. I'm going to check everything over and keep an eye on it and see what happens.