Mitsubishi Water Pump stops after ~1 minute.

[seefah]

Hi,

I have the Mitsubishi EP-205Q2 Constant Pressure Water Pump, date stamped 2008. Its been a great worker over the years, but it now has problem.

It stopped pumping (again) so I unplugged the pump from electric and opened all the taps upstairs and downstairs to drain the water. Then removed both top caps on the water pump to remove as much water as I could.
Filled up both cap holes and put the caps back on (bigger cap first on left, then the smaller one on right). The water pump starts for about 1 minute or so, filling the toilet systems etc, then stops working.

Even after removing power and back on again it does nothing. I've had to do the above steps before (a few times over the past year) to get the pump working again, but this time its not continuing after 1 minutes or so.

What can it be?

[lopburi3]

You are saying no water pressure when it turns off (you said when toilet fills and should shut off then)? Will it start again later?

Assume this is a water cooled pump? Perhaps the motor bearings are warn and now creating a higher heat (along with hot water) making it overheat? Does it feel hot? Will it last any longer with direct fan on it? Is it noisy? If it is starting again after cooldown it must be the overheat shutoff. If maybe getting to full pressure and then will not start again the pressure switch? Will it pump longer than one minute if you keep taps open?

[55Jay]

Did your pump run without water? Happened to me recently, somebody flushed the toilet and the stopper didn't seat all the way so the pump kept pumping water to it, sucked the 1,000 L tank down faster than city water supply could keep up and burned up the pump/impeller. I just replaced it with a new Hitachi constant pressure pump and of course, fixed the errant toilet plunger.

I burned up one of those small submersible pumps once in a similar way. It still works when submerged, for about 1 minute, gets hot and shuts itself off for 1 minute, then back on for 1 minute, etc....

[seefah]

So, the water pump went on for about a minute or so and filled the 2 toilet systems upstairs, then the pump switched off as it should. I then opened each tap individually to let some water through which gets rid of the discoloured water. In between each tap the water pump would switch off and on again as it should. Then at the last tap, maybe after about 1 minute or so, water started to come out then into a dribble, the water pump had stopped again. If I leave a tap open and unplug the water pump electric then plug it in again, nothing. No sound, no movement.

Its not the quietest of pumps, but I don't think its any louder then say a few years ago. I don't think the pump creates hot water from over heating, but with long use the pump can get quite warm to hot.

[chiang mai]

It's broken, just guessing.

[seefah]

Apparently when I was out today, my wife says it was working for about 1 hour, enough to get some laundry done.

[seefah]

So I went through the same procedure as I previously said, but the pump doesn't pump any water or make a sound. This is so frustrating.

Edited September 30, 2014 by seefah

[lopburi3]

Don't know where you live but in any city there are pump shops that can send someone to check it at reasonable cost - does not sound as if anything you can fix yourself if pump is not sensing it needs to start - but may not be expensive to replace electric contacts if that is the only trouble.

[wayned]

IMHO, it's most likely either a defective pressure switch or the motor binding causing the thermal overload protection to cut it off.

The first thing that I would do is eliminate the pressure switch. The switch is in a small , normally gray, round enclosure attached to the top of the tank with two wires coming out of it, usually one gray and one red. If you short the two wires together when the motor is not running, and is supposed to be, and it starts the switch is bad.

Having said that, if you are not electrically inclined leave the troubleshooting up to a technician and let him light himself up! If you are so inclined, remove the cover on the switch and short the two wires together where they are connected to the switch OR follow the wires where they come out of the switch and access them where they are connected to the motor wiring, normally in the box that covers the start capacitor.

The last switch that I bought was around 600 baht. The better ones have two sets of contacts so you can move the wires when the set you are using goes bad..

The next culprit is the bearings on the motor. If they are bad they could be causing the motor to overheat causing it to cutoff. With the power removed, locate the end of the motor shaft on the end of the motor not connected to the pump. There might be a small cover that you will have to pop off. The shaft will have a slot in it. Insert a screwdriver and rotate the shaft. Does it make a scrapping noise or is it very hard to turn. If so either the bearings are worn or something is binding in the pump. It can be rebuilt or replace by a qualified tech cheaper than buying a new pump.

[Crossy]

Could also be the motor capacitor going bad when it warms up.

[seefah]

I'm in Pattaya, but the shop we originally bought the pump from only sells the complete unit, not parts, just like most other shops selling water pumps. Unfortunately the smaller independently owned shops were wanting silly prices when I asked, like 1,500 Baht just for the pressure switch, that should actually be just 600 Baht or less for a non-Mitsubishi brand. So I went off to Num Chai Service Centre on Sukhumvit Road and booked the engineer to come have a look. It was only 500 Baht. He suggested that both the pressure switch and the flow switch be replaced. All this young engineer did was unscrew a few things, no test meters or anything.

A phone call today from Num Chai came later afternoon <sigh> with a 2,900 Baht price, but would also have to wait 1 week for the parts to come from Bangkok. When my wife called them, they wouldn't give a breakdown of the cost. Now I'm thinking do I buy new for 6,700 Baht, or suffer 1 a week of inconvenience. If there were another shop with replacement parts, I'd get from there, but I don't know of any others.

I decided to take a look myself at the pump, and as wayned suggest, I shorted out the connection that the pressure switch connected into, but nothing.

I took a photos of the steps I did for others to see.

If you're doing this yourself, you'll need a large towel. Empty the water sitting in pipes by opening all the taps and letting the water drain. Then remove the left larger cap on top of the motor, then the right cap. If going further, then the pressure switch, then what I think is the water flow switch. As in order in my photos attached. When putting back together, just do in reverse.

Anyone got any other suggestions to try?

[55Jay]

5 days and counting

[Pib]

I would guess the problem is either the motor capacitor (they cost approx Bt50), the pressure switch (Mitsubishi switch cost around Bt600-Bt800...OEM/generic about half that price), or the constant pressure circuit board (couldn't guess on that price but probably around Bt2,000)

When it did work, did the motor started did the motor start immediately/get up to full speed also immediately or take say 15 seconds or more? If it took a while to get up to full speed, it could be the motor capacitor under the metal closure in the plastic box. If the cap is bad the motor may not even start...or once the motor seems to get running the motor can overheat after X-minutes and then shut itself down...and won't start working again until the protective thermal device/circuit breaker in the motor cools off after 30 minutes or so and resets itself.

Pressure switch could be intermittent.

Good luck in fixing the problem.

Edited October 4, 2014 by Pib

[seefah]

Pib, I don't see a motor capacitor, can you see that in any of my photos?

Indeed the pressure switch is about 650 Baht or more, but can't find shop with OEM version with same rating and thread size to screw back on.

Also not sure about the pressure circuit board. Even though the green light comes on with power, I suspect it might be the actual problem.

When working, after opening a tap, maybe 2 seconds before hear the pump start. Upstairs maybe 3 or 4 seconds.

[wayned]

There should be four wires coming out of the motor. Two of them will go to the pressure switch, on/off, and the other two will go to the cap. It's hard to see in your pictures and my pumps are all of the vertical type. It might be under that gray cover, forth picture down on the left, or under that mess of wires in the box, 7th picture down on the right. There has to be a start cap, a black rectangular sealed box with two wires coming out of it with the value in microfards written in white in on the side.

[seefah]

Okay, I see the rectangle capacitor is in the dark grey box that sits on top of the motor. It looks okay, nothing burst or blown.

[wayned]

1. If you shorted the two wires to the pressure switch and the motor didn't start the pressure switch is not your problem.

2. If you have turned the motor by using a screwdriver in the slot in the motor shaft, second picture down on the left, and it is not binging or making a bad noise the bearings are probably OK. If the bearings were bad the motor would have to be rebuilt and I doubt that you have the tools to do it yourself

3. The start capacitor could be affected by temperature without showing any indication of being blown (puffed out). The easiest way is to replace it. You should be able to pull it out of the enclosure to read the value, They're not expensive.

4. If that doesn't fix it the motor is most likely bad. It can be rebuilt if you can find a place that will do it but most will want to sell you a new pump.

If you do buy a new pump, I would take the old one to a shop and have them rebuild it so you have a spare. I've actually rebuilt them myself and have two spares, one that went through the flood in my townhouse in Bangkok.

[seefah]

Thanks wayned for your feedback. Answer / clarification to your points;

1. I think I correctly(?) shorted out the side contacts on the pressure switch, but not the wires. Like indicated in this picture I found. There is no way to short out the wires unless cutting them first.

2. I don't think the motor or bearings are bad. They turn smoothly with pretty much no noise.

3. I can replace the capacitor. The only electronic parts shop I know of is in Thepprasit Road near the petrol station. Not sure if they are open today, I suspect not. Do you know?

If I can get the capicitor component today, then I'll replace that first. If not, I might just get a new pump, reluctantly.

[wayned]

I live in the sticks in Nakhon Sawan Province so I don't know the store.

If they don't have a capacitor with the exact same capacitance one close will work and would tell you if the old one was bad..

If that doesn't work , before getting a new pump, I would eliminate the pressure switch by cutting the wires and twisting the two going to the motor together and then applying power. There could be an internal open in the switch but normally it's the contacts.

[Pib]

Okay, I see the rectangle capacitor is in the dark grey box that sits on top of the motor. It looks okay, nothing burst or blown.

For the great majority of capacitors you can not tell by just looking if it's bad/going bad. You need to check the capacitance value with a meter and do a dielectric breakdown test (requires special equipment) to do a complete test. Anyway, when a motor start/run capacitor is defective it will display one or more of the following problems: motor won't start, motor starts very slowly, motor will not reach full speed/turns slower/has low torque, motor runs hotter and can actually overheat, etc.

Just last week I had to change the start/run cap in one of my floor fan motors, a 1.5 microfarad cap that cost Bt20 at an Amorn store. The defective cap physically looked fine...looked like new...but was causing the motor to sometimes not start unless I tapped the motor, when the motor did start it took a good minute to spin up, it was not reaching full speed, the high speed setting felt like the low speed setting use to be. Changed the cap....fan is now working fine.

Your pump motor start/run cap was in one of the pictures you posted...it's in the plastic box with a metal covering over the cap...with the plastic box the metal cap is probably secured with a small screw at the bottom of the plastic box.. The cap is probably a 4 to 6 microfarad cap (varies by motor size) which costs about Bt50 at a Amorn found a quite a few malls...like in/around a Lotus mall. Amorn stores sell a lot of these start/run caps for motors because there are a lot of cap failure, especially in a tropical environment. I've got a spare cap when my pump motor start/run cap fails and it will eventually fail...sometimes these caps seem to last forever...sometimes they only last a few years. I changed a start/run cap on my mother-in-laws ceiling fan last year...it was turning slow and took a long time to get up to speed...that fan was probably 20 years old. I change a large 45 microfarad compressor motor run/start capacitor in one of my split-air cons earlier this year because the compressor was making a funny noise during startup...change the cap...funny noise gone and it now pulls less current when running...that cap cost me less than a Bt100.

Not saying this is your problem, but it very well could be.

[Pib]

Thanks wayned for your feedback. Answer / clarification to your points;

1. I think I correctly(?) shorted out the side contacts on the pressure switch, but not the wires. Like indicated in this picture I found. There is no way to short out the wires unless cutting them first.

2. I don't think the motor or bearings are bad. They turn smoothly with pretty much no noise.

3. I can replace the capacitor. The only electronic parts shop I know of is in Thepprasit Road near the petrol station. Not sure if they are open today, I suspect not. Do you know?

If I can get the capicitor component today, then I'll replace that first. If not, I might just get a new pump, reluctantly.

The "Contact" label pointing to a small screw is "not" the electrical contacts; that screw is the pressure "span" adjustment screw...the main pressure adjustment screw is on the very top of the spring assembly. Don't mess with these pressure adjustments unless you know what you are doing and have a pressure gauge.

The electrical contacts are near the bottom of the switch assembly...you need to look into the "side plastic slots" on the assembly to see the electrical contacts....I can see the slots in your picture. There should be two sets of contacts. Problems with these contacts can be just being worn out, burnt/carbonized which prevent a good electrical connection, some even weld together prevent the pump from cutting off, or even ants/bugs preventing contact---some ants just like to be around electrical fields/contacts. Get a flashlight and look in those side slots to see the contacts and their condition...it should be clean around the contacts so blow/clean out any ants/bugs/etc. BE SURE POWER TO THE PUMP IS TURNED OFF WHEN DOING THIS.

Edited October 5, 2014 by Pib

[Pib]

This close up of a pressure switch shows one set electrical contacts as seen through one of the slide slots on the pressure switch assembly. You should have two sets of contacts...the other set can be viewed in the other side slot. The switch in the picture was about 5 years old when failing...it failed by the contacts welding together which turned the motor on continuously...fortunately I was home when this happened and immediately noticed the pump was running, running, running with no water being drawn anywhere. In this same picture you can see the pressure span adjustment screw...remember, that screw is "not" the electrical contact.

Now the contacts in this picture probably looked good to you because this is "after got the contacts unwelded/pulled apart and I cleaned them up with special contact cleaning files." I did this after buying and installing a new switch. I keep the repaired switch as a spare, but have since bought a new switch/generic switch as a spare (approx Bt250)...so now I have a new spare and a used spare---what you bet my current switch never fails again with all these spares just waiting to take its place.

[wayned]

All this info about the switch is good info, but the OP can isolate the problem to the switch by doing what I suggested. With power off, cut both wires going to the switch. Strip the wires and twist the ends of the two wires going to the motor together. Apply power. If the motor runs the switch is defective, either replace or repair it. If it does not, then the problem is either the start capacitor or the motor. The switch is now out of the loop and the wires can be reconnected later!

Now move on. If the motor starts replace or repair the pressure switch. If it does not leave the two wires twisted together and replace the start capacitor. If the exact same size is not available one close will do. I just rebuilt a spin motor and did not have a 8uf cap as installed in the washer so I used a 10uf to test it. Starts fine.

If that doesn't fix it then the motor must be bad. It can be rebuilt but finding someone to do it might be a problem and they will want to sell you a new pump!

[seefah]

Switch seems clean enough. I also put the end of the screw driver in at the bottom of the spring to short the contact, but nothing.

Edited October 5, 2014 by seefah

[sandyf]

Thanks wayned for your feedback. Answer / clarification to your points;

1. I think I correctly(?) shorted out the side contacts on the pressure switch, but not the wires. Like indicated in this picture I found. There is no way to short out the wires unless cutting them first.

2. I don't think the motor or bearings are bad. They turn smoothly with pretty much no noise.

3. I can replace the capacitor. The only electronic parts shop I know of is in Thepprasit Road near the petrol station. Not sure if they are open today, I suspect not. Do you know?

If I can get the capicitor component today, then I'll replace that first. If not, I might just get a new pump, reluctantly.

If you are in Pattaya, the best source of electrical parts is the Amorn shop, in the bottom of Tuk Com on south Pattaya road.

[wayned]

In the picture above the switch has a small red plug on the end of the wires. Unplug the switch and short the two pins together in the plug that it plugs into. You have isolated the switch. If the motor starts the switch is bad if not it's the start cap or the motor as said in above post #23.

[sometimewoodworker]

Switch seems clean enough. I also put the end of the screw driver in at the bottom of the spring to short the contact, but nothing.

That wouldn't do it as the Mitsubishi presure switch is a magnetic one.

To test if it is the pressure switch short the 2 pins on the top of the flow switch where you would plug the presure switch in. The flow switch is the one with the three wires, red black and grey and it is where you see the green LED.

There is no need to cut any wires to check that.

I had a problem with my EP-155Q 2 months ago and called Mitsubishi in Bangkok the technician spoke some English and diagnosed the fault over the phone. It was the flow switch an cost just under ฿1,700 including EMS. They are at https://www.mitsubishi-kyw.co.th/index.php. 02-763-7000 ex2999

FWIW you can easily take the pressure switch to pieces if you are slightly careful. You won't be able to access the contacts as they are sealed inside but you will be able to hear them making and breaking as you move the ring magnet past them. It comes apart from the bottom with the 6 screws 2 of them are longer and hold the metal top part on. You will be able to see that the diaphragm is still OK.

Edited October 5, 2014 by sometimewoodworker

[seefah]

Thanks everyone for your helpful suggestions.

I believe it is the flow switch, but I'm not prepared to wait a week for that to come. So in the end I bought a new Mitsubishi pump. Seems like every store at the moment are trying to push Hitachi pumps, hope I made the right choice with Mitsu.

What I'll do with the old one I'm not sure. Unlikely to keep it, so does anyone know of someone who will buy for parts?

[55Jay]

[wayned]

Thanks everyone for your helpful suggestions.

I believe it is the flow switch, but I'm not prepared to wait a week for that to come. So in the end I bought a new Mitsubishi pump. Seems like every store at the moment are trying to push Hitachi pumps, hope I made the right choice with Mitsu.

What I'll do with the old one I'm not sure. Unlikely to keep it, so does anyone know of someone who will buy for parts?

If it was me I would fix it and keep it as a spare!