Repairing Mitsubishi Waterpump WP-105QS

[Banana7]

In the attached diagram, what is the purpose of part 16, and how does it work, in a Mitsubishi water pump?

 

[VocalNeal]

Something to do with self priming.

[lopburi3]

Believe it is the control for amount of air in tank (so does not become full of water) - they can fail and require repair or replacement.  At least that looks like what I had to fix on a 405 units several decades ago.

[Banana7]

On 8/15/2020 at 10:15 AM, lopburi3 said:

Believe it is the control for amount of air in tank (so does not become full of water) - they can fail and require repair or replacement.  At least that looks like what I had to fix on a 405 units several decades ago.

The air in the tank seems to be disappearing. Can part 16 be repaired or should be replaced?

[Don Mega]

6 minutes ago, Banana7 said:

The air in the tank seems to be disappearing. Can part 16 be repaired or should be replaced?

That part is Bt.295.00, Doubt it can be repaired.

 

https://www.lazada.co.th/products/wp-i338880937-s656800170.html?spm=a2o4m.seller.list.7.39f82264G0n4BJ&mp=1

[lopburi3]

4 minutes ago, Banana7 said:

The air in the tank seems to be disappearing. Can part 16 be repaired or should be replaced?

In a younger day I repaired but still had to replace after a few months - just have someone replace - should not cost much (and you do not want to put much into it as believe that is the smallest pump they make).

I said that before checking price - about 4k now - back in the days could get the 405 model for that price.  Seems these pumps have become much more expensive in last several decades.

[Banana7]

On 8/16/2020 at 2:19 PM, Don Mega said:

That part is Bt.295.00, Doubt it can be repaired.

 

https://www.lazada.co.th/products/wp-i338880937-s656800170.html?spm=a2o4m.seller.list.7.39f82264G0n4BJ&mp=1

Thanks but the same part at MITSUBISHI ELECTRIC KANYONG LTD, is 161 baht.

[Don Mega]

31 minutes ago, Banana7 said:

Thanks but the same part at MITSUBISHI ELECTRIC KANYONG LTD, is 161 baht.

Fantastic, hope it sorted your problem.

[Banana7]

On 8/15/2020 at 10:15 AM, lopburi3 said:

Believe it is the control for amount of air in tank (so does not become full of water) - they can fail and require repair or replacement.  At least that looks like what I had to fix on a 405 units several decades ago.

You are right, the part is called an air charger. I replaced parts 15, 16, 17, 18 in the diagram and the pump is running differently now.  Parts 17 and 18 were glued together to ensure an airtight seal. Time will tell if the fix has worked. Attached is the parts receipt, in case anyone has the same issue.

 

If the holding tank starts to leak, like mine did, replace it with a stainless steel copy, available from Lazada. On the original tank it was impossible to remove part 17, the air charger tube and there was no part 18.