Coolant Leak from water pump even when replaced

[ulster exile]

I've a Hornet 600 '02 model - when doing some other work a few weeks ago hubby noticed a slight leak from the bottom of the water pump. He took it off, cleaned it (no signs of what was wrong) and replaced the large o-ring inside it. After snapping the bolts, figuring out the torque wrench was f%cked and being unable to drill out the bolts easily, we simply replaced the water pump with another 2nd hand part.

After riding the bike for a week it was laid up again after a little scrote tried to break the disk lock off with a rock, knackering the brake disk and after another few days of it being laid up I noticed another leak from the bottom of the replaced water pump!

It's coming from the inspection hole at the bottom of the water pump. The workshop and Haynes manual say that the mechanical seal has gone and to replace the pump as it's not a serviceable item.

Although we can't guarantee that it's the same problem causing both leaks, it seems most odd. Before we buy a 3rd pump, has anyone any ideas as to what could have caused the seal to go?

Thanks in advance.

[Odie]

The mechanical seal inside the pump has gone, cannot be rebuilt, need a new pump.
Odie
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[Walloper]

The inspection hole is called a 'Tell-Tail' Hole.
It's function is to prevent oil transferring from the oil side (water pump bearing) to the water (radiator engine coolant) or vice versa should the seal/s integrity be compromised.
It's secondary function is to give you prior warning that the lip type seal on the water pump shaft is worn.
Normally you would also find a groove worn into the water pump drive shaft which permits oil/water to leak past..
This is the risk of using 2nd hand parts with unknown/uncertain history.
If you can get access to the parts inside without destroying the pump then you may be able to get a new seal and a shaft wear sleeve. But to track down the parts may be a nightmare.
Cost to do this (parts and labour for a workshop) is more than the cost of a NEW pump usually. So the OEM deems repair kits obsolete therefore the pump is regarded as 'Sealed for Life'. Life being what the designers regarded as a 'normal service life' for this part.
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair