I have a Mitsubishi pump that has developed a leak underneath. I have noticed that it runs occasionally without turning on any taps, and today I see some water around the base. Putting a finger underneath the pump I can actually feel a jet of water squirting out under pressure, so does this mean the tank has rusted through and a new pump is in order? The pump is now 8 years old but only gets used when the mains water is either off or low pressure.

There is a pin hole rusted through in the tank. It/they can be temporarily fixed by the old tinker method of putting a screw into the hole. In the modern era covered with epoxy glue. 

 

But for around 1600 baht+/- you can get a new yellow tank.  If it is your house/pump for around 3000 you can get a stainless tank, if they have one.

 

Depending on where you live you need to find your nearest hardware/pump shop, take a picture of your pump or the model number written down. 

 

The replacement is easy and requires only a few basic tools after first disconnecting the power and turning the water supply off. You disconnect the inlet and the outlet and undo two bolts and two nuts on the top and lift the pump off the tank.

5 minutes ago, VocalNeal said:

There is a pin hole rusted through in the tank. It/they can be temporarily fixed by the old tinker method of putting a screw into the hole. In the modern era covered with epoxy glue. 

 

But for around 1600 baht+/- you can get a new yellow tank.  If it is your house/pump for around 3000 you can get a stainless tank, if they have one.

 

Depending on where you live you need to find your nearest hardware/pump shop, take a picture of your pump or the model number written down. 

 

The replacement is easy and requires only a few basic tools after first disconnecting the power and turning the water supply off.

Thanks. Can the water pipe connections just be disconnected at the flanges and bolt on to a new tank, and can the upper part of the pump be easily disconnected from the tank? Are you talking about a S/S tank like this?

Having a closer look at the pump, fitting a new tank might be beyond my capabilities. There are quite a few fittings attached to the tank that look like they would require gaskets. A whole new pump can be had for just over 5000 baht so that might be the way to go.

1 hour ago, giddyup said:

Having a closer look at the pump, fitting a new tank might be beyond my capabilities. There are quite a few fittings attached to the tank that look like they would require gaskets. A whole new pump can be had for just over 5000 baht so that might be the way to go.

It is the same job to replace the whole unit. The only difference is the two connections on the top. One has an o-ring used again to seal that hole the other is just two nuts, no water connection. Your picture has too many connections. You don't have to disconnect the power. The motor has two nuts holding it.

 

Same amount of work to do either job! If you can replace the whole thing including the electrical work, you can certainly replace the tank only. From memory the pressure switch can be unscrewed without removing the wires.

 

 

The two nuts (10mm from memory) in the foreground left hide the O-ring to reuse. The pressure switch centre can be unscrewed. They are the only two water connections connecting the tank to the motor/pump unit. The motor/pump has four nuts also 10mm holding it on the tank.  Two can be seen the other two hidden behind the black tube.