Start capacitor in water pump motor

Thread Starter

Small motor Pete

Joined Jul 2, 2019
7
Hi all,
I have a Finsbury Engineers, Hampton Parkinson 240v AC water pump (40+ yrs old) that has an issue presumably with the starter capacitor.
It will on occasions start, and run fine - however it more commonly will just make a noise like it is trying to engage and fail to start before the safety throws out.
I presumed it was a faulty start capacitor and have pulled it down looking to replace it... but I can’t find anything that resembles a run or start capacitor!
I’ve attached photos - so hopefully someone will be able to shed some light for me!
Thanks for the help!
DA994E1D-B734-4FEF-B369-7241A583EAF8.jpeg

42AF27DE-244B-4D17-ADD9-06735D30AB48.jpeg

7FEDD332-14C8-4EF5-A972-87A850B7111A.jpeg
 

Bernard

Joined Aug 7, 2008
5,283
Maybe there is no capacitor ? ; just a run & start winding. If the centrifugal switch does not connect the start winding at start until speed is reached then there will be a high stall current tripping breaker ?
 

Thread Starter

Small motor Pete

Joined Jul 2, 2019
7
Maybe there is no capacitor ? ; just a run & start winding. If the centrifugal switch does not connect the start winding at start until speed is reached then there will be a high stall current tripping breaker ?
Thanks - that’s probably correct seeing as I can’t find any start or run capacitor.
If it is the centrifugal switch, which seems to be in good condition, how could I rectify the starting/stalling?
 

SLK001

Joined Nov 29, 2011
1,527
I've had the centrifugal switch stick and not disengage the start windings once up to speed. Clean the moving parts and put some oil on the moving parts and see if that works.
 

BR-549

Joined Sep 22, 2013
4,940
How is the fit and feel of the bearings, seal and impeller?

Sometimes it takes a little time for a dry bearing to take affect.
 

Thread Starter

Small motor Pete

Joined Jul 2, 2019
7
I've had the centrifugal switch stick and not disengage the start windings once up to speed. Clean the moving parts and put some oil on the moving parts and see if that works.
It seems that this switch presses against the centrifugal switch at rest, which must engage the start winding.
2B42D984-A08D-4B11-8D02-04193CE81421.jpeg
With it pulled apart and powered like this, it makes the same noise as it does when it’s stalling/trying to start.
I’ve tweaked the position of copper to see if that’s what’s the issues, but to no avail. 9EA6C458-5221-41CD-A94F-FE041B4BA428.jpeg
 

MaxHeadRoom

Joined Jul 18, 2013
19,156
If the start winding's are not engaging, a spin at switch on in either direction will start it running, this is a true sign that a start winding is not engaging.
The switch is N.C. when stationary.
High unusual to have no Start Cap!
Max.
 
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Thread Starter

Small motor Pete

Joined Jul 2, 2019
7
If the start winding's are not engaging, a spin at switch on in either direction will start it running, this is a true sign that a start winding is not engaging.
The switch is N.C. when stationary.
High unusual to have no Start Cap!
Max.
Thanks Max. Yes, I had thought that I could give it a spin to get it started; however the spindle locks solid and won’t spin at all, even if I had it spinning prior to powering on.
 

Ylli

Joined Nov 13, 2015
788
Just to add my 2¢...

Be sure the contacts on the centifugal switch itself are clean. If you can, isolate the switch and use an ohmmeter to be sure it functions properly.

Then there is the centrifugal unit on the motor shaft, the thing with weights and springs. Be sure that the weights can be pulled outwards and that doing so moves the actuator plate. Then be sure the springs freely retract things again. Finally, make sure the actuator has not slipped on the motor shaft and properly actuates the switch when the plate moves back and forth.
 

profbuxton

Joined Feb 21, 2014
418
From the pics I cannot see where a start cap would fit into the housing. Did the motor run before?. Is there any sign of a cap. mounting external?. How many connections are there on the motor terminals?
 

Thread Starter

Small motor Pete

Joined Jul 2, 2019
7
From the pics I cannot see where a start cap would fit into the housing. Did the motor run before?. Is there any sign of a cap. mounting external?. How many connections are there on the motor terminals?
No, there doesn’t appear to be anywhere where a start cap could be hiding.
It had been sitting dry for some time, then started first time yesterday - ran perfectly. Then after I switched it off and tried to run again, it had the stalling issue.
There’s 4 terminals that are accessible through a plate on the front; I’ll post up a pic of them when I get home. I’ve pulled down and cleaned them all and checked the connections are good.
 

LesJones

Joined Jan 8, 2017
2,342
Post #11 suggests to me that there may be enough play in the bearings for the rotor to be pulled into contact with the stator causing the motor to lock. You could try marking the rotor all over with a felt tip pen and after the fault has occurred checking to see if any of the marking with the felt tip pen has been rubbed off.

Les.
 

MaxHeadRoom

Joined Jul 18, 2013
19,156
Post #11 suggests to me that there may be enough play in the bearings for the rotor to be pulled into contact with the stator causing the motor to lock. You could try marking the rotor all over with a felt tip pen and after the fault has occurred checking to see if any of the marking with the felt tip pen has been rubbed off.

Les.
If there was axial play in the rotor, it could also cause the cent. switch to move off the contact that initially connects the start winding.
IOW's, they open prematurely.!
Max.
 
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shortbus

Joined Sep 30, 2009
7,074
From the pics I cannot see where a start cap would fit into the housing. Did the motor run before?. Is there any sign of a cap. mounting external?. How many connections are there on the motor terminals?
It may not even need a start cap, it it is a "split phase" motor. Which is pretty common on water pumps and even small air compressors.
 

shortbus

Joined Sep 30, 2009
7,074
Post #11 suggests to me that there may be enough play in the bearings for the rotor to be pulled into contact with the stator causing the motor to lock.
If there was axial play in the rotor, it could also cause the cent. switch to move off the contact that initially connects the start winding.
Seen that happen when the 'fiber' thrust washer gets left out when somebody takes a motor apart. Or they find it when taking one apart and don't know where it goes and put it on the wrong end.
 

Thread Starter

Small motor Pete

Joined Jul 2, 2019
7
After plenty of stuffing around, I took it to a motor rewinding company and they had a look for me.
The age of the motor predates start capacitors.
What they suspect is the problem is a cracked rotor. Hence why it will also lock solid when trying to start once power is put to it.
Sadly, it’s well past the age of any one making replacement parts, and she will now be destined for the metal recyclers.
Thanks to everyone for their help!
 
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