Troubleshooting coolant pump

[gangel99]

The coolant pump on my horizontal band saw stopped working - it just hums. Replacements are very pricey so I would some help troubleshooting - and my theory is the capacitor. I have a voltage tester but not entirely sure what to test.

Specs: The capacitor is 4uF, WV is 250 VAC (guessing this means working voltage), and it is wired for 110 VAC which is one of the options listed on the motor. The coolant motor is Taiwanese, 1/8 HP, Type YC, 110V/120V, single phase, 2 pole. The saw is circa 1995 and the saw runs, albeit without coolant.

The tests I think I need to perform are:
1) Voltage to the cap - should be 110V
2) Voltage across the cap - ????

Is there anything else I should do? I dumped the coolant tank, cleaned some chip / oil sludge from the pump, but do not know how to determine if the pump is clogged somehow.

Thanks for any tips.

[hammermill]

lubricate the motor bearings and make sure it turns freely, use alite oil for this job, if it has one take off the pump bottom plate and clean, again make sure it turns freely eletricialy 11o volts to the motor if the cap is a run capicator it will not have a start switch in series with it



note the type yc motor should be capicator start in that hp range so check/clean the start contacts (motor diasabembly required)

[redneckalbertan]

I just had problems with a coolant pump, it turned out to be the check valve that was in line. It was sticking closed and wouldn't let anything through. Something to check... Pun intended!

[DianneB]

90+% of the time, it is the capacitor that fails - they have a limited life and they are cheap. It is also not possible to measure anything useful with a DVM - the function of the capacitor is to provide a phase shift - so just replace it and see what happens. You can always return the new one if that wasn't the problem.

[oldgoaly]

the reason the cap has a 250v rating is when the motor spins it block the counter-emf the motor develops while running with out using a relay the cap takes the start winding out of the circuit.
I would disassemble the motor/pump make sure the pump is clean and lube the bushing or bearing, most likely it is not a ball bearing motor, if it has bushing soak the reservoir on each end with a light oil, many are felt like wadding some are a wood by-product, yep looks like saw dust. If possible drill a 1/8" hole in each end so you can add oil every year or so.

[stevec]

Ditto on the oldgoaly!

[gangel99]

Thanks for all the information. I did determine that power is going to the cap, and that the pump vane (connected to the motor) turns easily. I am going for the easy repair - replacing the cap - before I start taking more things apart that I might not be able to put back together. The only problem I have is I can not find a specific replacement. The closest I can find is 4uf and 370 V rather than 4uf and 250 V. I think this will be OK from what I read but electronics are not my strong point so I'm going to find a good motor electronics distributor and rely on the sales folks (i.e. no eBay or Amazon).

[hammermill]

you will be fine with the higher voltage rated cap