New Mitsubishi pump design flaw?

[Thaigang]

Recent purchase and install of WP 305R for shallow well (7m): All looked good until I noted a drip from where the intake pipe enters the check valve housing. As the motor cycles, a slight flex is seen due to torque of motor starting; it releases when up to pressure and motor switches off. Back to Quality Homemart for exchange. Second new pump installed and same situation. (Older model 305QS was doing the same and I thought it worn and needed replacing.) This is either a design flaw or I'm just not very lucky with Mitsubishi pumps. Reseller is reluctant to exchange or refund. Since the Thai Mitsubishi website does not appear to accept English enquiries, I sent to Mitsubishi Malaysia asking their opinion. If anyone has experienced this problem or has knowledge of how the seal is designed, I would be interested in your observations. Here's a link to a short video. See below for images.

[Isan Farang]

Seems very strange 2 new pumps would leak from the exact same spot, rather than mess around with the new pump why not order a new o ring and fit to the old pump.

 

You can find the O - Ring in the attachment

Mitsu Pump Parts 2016.pdf.pdf

[carlyai]

18 minutes ago, Isan Farang said:

Seems very strange 2 new pumps would leak from the exact same spot, rather than mess around with the new pump why not order a new o ring and fit to the old pump.

 

You can find the O - Ring in the attachment

Mitsu Pump Parts 2016.pdf.pdf 3.97 MB · 1 download

I think that's a good idea.

Lazada has some Mitsubishi pump parts or there is a shop in Burriram that seems to have everything. Contact Bob.

I have just repaired my WP305QS pump. Low pressure and pressure switch would not cut off pump, so I ordered an impeller, housing, o-ring from Mitsubishi Thailand. The ordering and payment went OK, but the parts never arrived. I sent a few emails to the contact with no replies so today I sent a message in Thai to one of the cc at Misubishi and received a message that parts would be sent Monday.

I also had a leak from the bottom of the pipe you are referring to. I had some vasaline for orings and seals that I always apply to surfaces, but ran out so used some white grease that seemed to work OK. A light smear of grease can help with sealing.

 

[Isan Farang]

22 minutes ago, carlyai said:

I think that's a good idea.

Lazada has some Mitsubishi pump parts or there is a shop in Burriram that seems to have everything. Contact Bob.

I have just repaired my WP305QS pump. Low pressure and pressure switch would not cut off pump, so I ordered an impeller, housing, o-ring from Mitsubishi Thailand. The ordering and payment went OK, but the parts never arrived. I sent a few emails to the contact with no replies so today I sent a message in Thai to one of the cc at Misubishi and received a message that parts would be sent Monday.

I also had a leak from the bottom of the pipe you are referring to. I had some vasaline for orings and seals that I always apply to surfaces, but ran out so used some white grease that seemed to work OK. A light smear of grease can help with sealing.

 

I just changed both my pump tanks to stainless, all the gaskets and o rings I obtained from a big pump supply shop in Ubon.

 

On that housing there is two sealing area's

1. O Ring at the top of the housing pipe

2. Flange Inlet Gasket

[Thaigang]

Thanks for the pdf but the link won't open (file extension problem?). I will definitely look at repairing the old pump since the intention is to use it elsewhere. The new pump is required.

[Thaigang]

This WP 305R model has the delivery pipe going into the housing which itself has a flange to mate with the upper portion (where it diverts to the area containing the check valve - see photo). That upper flange is where slight movement occurs. Pipe is stationary while upper housing flexes downward with torque from motor starting. 

[Isan Farang]

27 minutes ago, Thaigang said:

Thanks for the pdf but the link won't open (file extension problem?). I will definitely look at repairing the old pump since the intention is to use it elsewhere. The new pump is required.

You need to take the new pump back to the supplier and tell them to send back and have Mitsu check it out. If you go and take apart you will have no chance of any warranty. I have had a few of these pumps and never observed a leak at that sealing area.  

[Thaigang]

6 minutes ago, Isan Farang said:

You need to take the new pump back to the supplier and tell them to send back and have Mitsu check it out. If you go and take apart you will have no chance of any warranty. I have had a few of these pumps and never observed a leak at that sealing area.  

I won't be taking the new "R" pump apart because I'm hoping the dealer will exchange or allow switching to the Hitachi 300XX model for the difference in price. I will still go ahead and repair the older "QS" model and would sure like to know where that great-looking stainless tank can be had. I'll buy one if possible for my "QS" refurbishment. 

[Thaigang]

Isan Farang, pdf downloaded on phone. Thanks for that. 

[Isan Farang]

17 minutes ago, Thaigang said:

I won't be taking the new "R" pump apart because I'm hoping the dealer will exchange or allow switching to the Hitachi 300XX model for the difference in price. I will still go ahead and repair the older "QS" model and would sure like to know where that great-looking stainless tank can be had. I'll buy one if possible for my "QS" refurbishment. 

Had to purchase additional o rings from my pump shop that was not supplied with the tank

 

https://www.lazada.co.th/products/i261551164-s402499067.html?urlFlag=true&mp=1

[carlyai]

Here's some info. on the impeller bits and pieces. For the future.

 

[sometimewoodworker]

5 hours ago, Thaigang said:

Since the Thai Mitsubishi website does not appear to accept English enquiries

The website may not but Mitsubishi in Bangkok has English speaking tech staff who will talk to you.

 

I had a problem, it was diagnosed reasonably quickly, I ordered the replacement part, it was sent EMS, fitted it, problem solved.

[Thaigang]

Thank you for the parts listing "Carlyai". And "Sometimewoodworker", thanks for the heads up on Mitsubishi Thailand's English-speaking techs. I'll try a call this morning. 

[pineapple01]

This send it back isnt a good Idea. Remember all the "How Much Longer You Be" you put up with fitting the dam thing.????

[Thaigang]

For whatever reason the search for Mitsubishi Thailand's website, today, provided an option to display in English. I sent my enquiry and will now attempt a phone call to see where that goes. Here's the link if anyone cares to record it: Mitsubishi Electric Thailand

And, just found another link that points to Mitsubishi Electric Kang Yong website. I gather the first is corporate head office and the other is ... well, maybe manufacturer for some Mitsubishi products in Thailand?

Cheers to all for your input. I'll report back on the outcome.

Edited July 11, 2020 by Thaigang
additional information

[Boomer6969]

16 hours ago, carlyai said:

Lazada has some Mitsubishi pump parts or there is a shop in Burriram that seems to have everything. Contact Bob.

You mean Ruangsangtai? They have another guy called Moses whom I trust at lot more than Bob. I had a major disaster with this shop, lost quite a bit of money, but they are resourceful and an obvious choice for maintenance and supply of parts.

[carlyai]

Another parts list to share.