first of all, thanks all the inputs in this following post that provided me all the information needed to attempt replacing the water pump of my 2009 LS 460.
https://www.clublexus.com/forums/ls-...waterpump.html

My 2009 LS460 has ~68k miles on it. Dealer detected water pump leakage. I replaced the water pump today, together with Radiator, thermostat, serpentine belt, upper & lower hoses.

The old water pump photos are attached, just curious what went wrong with this water pump, looks like it is leaking through the gasket

thanks

 

Looks like corrosion. You ever fill up your coolant yourself and not used the proper coolant or right mixture amount? One of the biggest jobs of the coolant is corrosion protection.

 

thanks for the hint, yes there is a trace of orange rust in the lower part of the water pump. the coolant drained out yesterday was fresh pink color just like new toyota coolant.
only 6 month ago i started to fill it up due to the coolant leakage, with the toyota coolant.

 

Thanks for the great pictures. Your question as to what went wrong is a good one. Makes me wonder if this is not a torqueing issue.

 

thanks.. just want to find out if there is anything particular that's causing the water pump to leak. the pump itself looks in good condition, not sure why it leaked. the attached photo shows the old vs new water pump, and the old pump before being removed.

 

interestingly, the contact (gasket) surfaces of the two pumps looks very different. Was the a Lexus OE replacement part?

 

It's very strange for a gasket to leak like that so many miles after installation, I'd be willing to bet the weep hole was leaking coolant and the coolant blew back onto the pump...making it appear as if the gasket was leaking.

But you never know.

 

the new water pump is made by aisin, same with the original one, by aisin.
the new pump fit very well, no leak so far...

 

The leak is not a gasket issue. The leak will (99% of the time), come from that area because of the "weep hole". When the pump starts to fail, a "tell tale" will allow the pump to still work and not fail catastrophically, allowing the owner to replace the pump when convenient (within reason). That's where the accumulation of pink crust forms. The key to replacing the pump is making sure you follow the proper torque sequence as well as the two different torque specs for the different bolts around the edges. The good thing about replacing the water pump on these cars is that it's a pretty simple job for a DIY'er.