Leaking pump tank

[Susco]

Since a few days I noticed that when using water Mitsubishi pump cycles pressure like every 10 seconds.

 

Went to look in the pump house and there as little water under the pump, and on closer look there is a hairpin sized hole near the top of the tank.

 

Can't see the hole, so small, but see the water drips hanging there.

 

Does this cause the fast pressure cycle?

 

Could I just seal the hole or is this a futile exercise and should I replace the tank right away?

 

Any links to tanks at economical prices? I see them on Lazada, but they are stainless steel, so maybe a normal steel one will be significantly cheaper?

[NanLaew]

After the tank rotted out, I replaced the complete pump. Then I bought a generic stainless tank of lazada, dropped by the local water pump shop and bought OEM seals and rebuilt the motor and impeller on a 12 year-old pump. Tested it, drained it and kept it is a spare. Now grandma uses it to lift well water to irrigate her cool season allotment. Worthwhile investment IMHO and if you have the basic tools and are handy with them, it takes less than an hour to replace a tank.

[carlyai]

2 hours ago, Susco said:

Since a few days I noticed that when using water Mitsubishi pump cycles pressure like every 10 seconds.

 

Went to look in the pump house and there as little water under the pump, and on closer look there is a hairpin sized hole near the top of the tank.

 

Can't see the hole, so small, but see the water drips hanging there.

 

Does this cause the fast pressure cycle?

 

Could I just seal the hole or is this a futile exercise and should I replace the tank right away?

 

Any links to tanks at economical prices? I see them on Lazada, but they are stainless steel, so maybe a normal steel one will be significantly cheaper?

I've heard this happening to Lucky Star pumps because there is no airflow under the pump.

Some on this forum have replaced their tank with a stainless steel tank and if you can buy one on Lazada I think replacing it would be the best idea.

[Susco]

4 minutes ago, carlyai said:

I've heard this happening to Lucky Star pumps because there is no airflow under the pump.

Some on this forum have replaced their tank with a stainless steel tank and if you can buy one on Lazada I think replacing it would be the best idea.

 

I have a Mitsubishi, not a lucky star, and what is happening because no airflow under the pump.\

The small leak is at the top of the tank, so plenty of airflow there.

\

I have seen the stainless tanks on Lazada, but for a 305 it's over 3000 Baht.

 

Since the pump is about 8 years old, and originally they don't have stainless tank, I hope to find one in regular steel and cheaper than 3K.

 

Can the rapid pressure cycles and the leak be because the tank is flooded?

 

Isn't that tank supposed to contain only air?

[carlyai]

4 minutes ago, Susco said:

 

I have a Mitsubishi, not a lucky star, and what is happening because no airflow under the pump.\

The small leak is at the top of the tank, so plenty of airflow there.

\

I have seen the stainless tanks on Lazada, but for a 305 it's over 3000 Baht.

 

Since the pump is about 8 years old, and originally they don't have stainless tank, I hope to find one in regular steel and cheaper than 3K.

 

Can the rapid pressure cycles and the leak be because the tank is flooded?

 

Isn't that tank supposed to contain only air?

The tank contains water too. Did it cycle before the leak? Bit hard to tell but if everything was OK, and nothing's changed, I'd say the leak is causing the pressure to drop therefore the pump recycled on and off.

If you don't want to change the tank, maybe you can seal the hole with 2 part epoxy.

[Susco]

I don't know much about pumps, hence my question, but I have a hard time to believe the hole only is causing so much pressure loss.

 

There is no water jet coming out of that hole, when the pump runs there comes a drop of water out of it.

 

I think it is even closer to every 5 seconds than 10 that it starts running again.

 

Before it would be like every 30 seconds that the pump would run for 5 seconds

[sometimewoodworker]

25 minutes ago, Susco said:

Can the rapid pressure cycles and the leak be because the tank is flooded?

 

Isn't that tank supposed to contain only air?

It is precisely because the tank is flooded. The tank is supposed to contain mostly air. Plugging the hole and draining the tank will fix the problem, but if the tank is rotten then you need a replacement soon.

[Susco]

6 minutes ago, sometimewoodworker said:

It is precisely because the tank is flooded. The tank is supposed to contain mostly air. Plugging the hole and draining the tank will fix the problem, but if the tank is rotten then you need a replacement soon.

 

I don't notice any rust on the outside, how to check if the tank is rotten?

 

Are there replacement tanks in regular steel available that you are aware of?

 

I consider it a bit silly to spend +3K on a tank for an 8 year old pump, that may get tits up in a couple of years

[NanLaew]

2 hours ago, Susco said:

 

I don't notice any rust on the outside, how to check if the tank is rotten?

 

Are there replacement tanks in regular steel available that you are aware of?

 

I consider it a bit silly to spend +3K on a tank for an 8 year old pump, that may get tits up in a couple of years

 

My original tank on a 205 started weeping at the weld around the middle after about 10 years of use, rotted out about 2 years later.

 

Your tank has a pinhole at 8 years so maybe it would rot out in maybe 2 more years?

 

I considered the ~2000 baht stainless tank from lazada a worthwhile investment on a 12 year old pump that cost maybe 6000 baht and is still going strong.

Edited December 18, 2020 by NanLaew

[carlyai]

7 hours ago, NanLaew said:

 

My original tank on a 205 started weeping at the weld around the middle after about 10 years of use, rotted out about 2 years later.

 

Your tank has a pinhole at 8 years so maybe it would rot out in maybe 2 more years?

 

I considered the ~2000 baht stainless tank from lazada a worthwhile investment on a 12 year old pump that cost maybe 6000 baht and is still going strong.

I have pulled a couple of my pumps to pieces. Just threw in a new impeller, sanded out the impeller body scratches and Then good to go. My Lucky Star el cheapo sucks up sand from the aquifier as the seasons change, and sometime runs for ages without water (Modification coming). Not good for the pump but B500 change of the plastic impeller and all good. 

I'd keep fixing the pump instead of buying a new one.

[sometimewoodworker]

10 hours ago, Susco said:

don't notice any rust on the outside, how to check if the tank is rotten?

 

Are there replacement tanks in regular steel available that you are aware of?

Checking for a rotten tank is quite easy, but do have a replacement available when you check. The process is to tap  all round with something like a hammer or solid screwdriver handle. The sound of good steel is a ringing sound a little like a bell, rotten steel will thud or you will break through. Once you hear good and rotten steel it’s easy to recognise.
 

As you have a Mitsubishi all the genuine parts are available from Mitsubishi, you can probably get copy parts also, some copies are better than OEM.

[carlyai]

10 hours ago, sometimewoodworker said:

Checking for a rotten tank is quite easy, but do have a replacement available when you check. The process is to tap  all round with something like a hammer or solid screwdriver handle. The sound of good steel is a ringing sound a little like a bell, rotten steel will thud or you will break through. Once you hear good and rotten steel it’s easy to recognise.
 

As you have a Mitsubishi all the genuine parts are available from Mitsubishi, you can probably get copy parts also, some copies are better than OEM.

Parts are cheaper from Mitsbishi too. Ordered an impeller from the local tractor shop after Mitsbishi didn't respond, after a while nothing but by then Mitsubishi responded, so ordered one from them as well. Mitsubishi one came first and was half the price of the local tractor shop.

[Susco]

On 12/18/2020 at 9:02 PM, carlyai said:

If you don't want to change the tank, maybe you can seal the hole with 2 part epoxy.

 

Someone can advice which 2 part epoxy to use.

 

I tried to stick a small piece of plastic, by lack of anything better, on the whole using the 2 part epoxy from pattex, but it came of at the first start of the pump. Maybe it degenerates by age, as it doesn't seem to become bone hard. It was also pretty easy to peel off.

 

Should I sand it to bare steel?

 

Any other advice how to plug the hole is also welcome. The hole is now a little bigger, because by sanding it the paint that cover most of it came off, but it is still less than 1 mm in size. Can't get a paperclip inserted, so small.

 

I have checked the pump for rot in that area, and the sound is fine.

 

[sometimewoodworker]

8 hours ago, Susco said:

 

Someone can advice which 2 part epoxy to use.

 

I tried to stick a small piece of plastic, by lack of anything better, on the whole using the 2 part epoxy from pattex, but it came of at the first start of the pump. Maybe it degenerates by age, as it doesn't seem to become bone hard. It was also pretty easy to peel off.

 

Should I sand it to bare steel?

 

Any other advice how to plug the hole is also welcome. The hole is now a little bigger, because by sanding it the paint that cover most of it came off, but it is still less than 1 mm in size. Can't get a paperclip inserted, so small.

 

I have checked the pump for rot in that area, and the sound is fine.

 

Sand to clean steel then best is a spot weld, second best is a brazed fill, 3rd is a solder plug, but it’s going to be really difficult to get enough heat for that, last is any form of glue or epoxy.

[HighPriority]

My understanding is that the pressure tanks are old hat and the new pumps tend to have an electronic pressure switch.

It is a like for like replacement for the old tank (if you buy the current model of your old pump).

Id replace the old pump with new, have a crack @ repairing the old tank if you wish and keep the old pump as backup.

Id expect the inside of the old tank to be pitted, and any repair in one spot to be replaced by another pinhole in another spot...

[sometimewoodworker]

41 minutes ago, HighPriority said:

My understanding is that the pressure tanks are old hat and the new pumps tend to have an electronic pressure switch.

Pressure tanks are not old hat, they reduce or stop short cycling and will never be replaced by electronic control. Pressure and flow switches are standard with pressure tanks.

 

41 minutes ago, HighPriority said:

Id expect the inside of the old tank to be pitted, and any repair in one spot to be replaced by another pinhole in another spot...

It probably will, but how soon? Months? Years? 
 

Fixing the first 1 or 2 holes can give extra years and is a sensible choice.

Edited December 20, 2020 by sometimewoodworker

[Susco]

2 hours ago, sometimewoodworker said:

Sand to clean steel then best is a spot weld, second best is a brazed fill, 3rd is a solder plug, but it’s going to be really difficult to get enough heat for that, last is any form of glue or epoxy.

 

Epoxy is the only option I have for now. I found another epoxy in a drawer which seems to get harder, and is also much less liquid.

 

Should I just add the epoxy over the hole, or stick something like a coin on it?

Edited December 20, 2020 by Susco

[bankruatsteve]

24 minutes ago, Susco said:

or stick something like a coin on it?

Chewing gum.  Impossible to get off.  ????

[HighPriority]

4 hours ago, sometimewoodworker said:

Pressure tanks are not old hat, they reduce or stop short cycling and will never be replaced by electronic control. Pressure and flow switches are standard with pressure tanks.

 

It probably will, but how soon? Months? Years? 
 

Fixing the first 1 or 2 holes can give extra years and is a sensible choice.

2nd image is the original pump that was on my property when I purchased 18 months ago, age unknown.

It had run dry and spun out the impeller, I purchased the pump in the 1st pic to replace it. Note the absence of a tank... and it runs perfectly.

I am certainly not holding myself out to be any sort of expert in pumps, just relaying my experiences, I have no idea of your pump expertise.

As to your claim of a tank repair lasting years, yeah it might... but it might only last hours or days, without metallurgical scanning we don’t know do we ?

It will come down to how interested the OP is in repairing things, and how free his time is.

I serviced the old pump and have put it to use on the bore tank to irrigate my block.

[Susco]

I glued a coin on the hole with 2 part epoxy, and it seems to hold.

 

Should I cover the coin with epoxy as well, to make it stronger, or is that actually not a good idea?

Edited December 21, 2020 by Susco

[VocalNeal]

Sure that'll work. Another way is to coat a large short screw with epoxy and screw it in.