I have put together the following information in regards to rebuilding your LT1 water pump rather than replacing the entire unit. If your pump begins to leak through the weep hole in the casting, this is the culprit.

You can purchase a kit on ebay but the price is outrageous.
Let's see if we can work the magic of the forum to everyone's benefit.

This is my contribution; if you are, or know a maintenance manager with a seal sourcing contact, perhaps we can source it and save us all a great deal of money and grief.

If we can source it, I will do a first class laneway "how-to" with complete pictures.

Post Script - I have already tried to contact the Chinese manufacturer from whence the part number originates with no luck.

 

Here are some additional pics for those with the perspicacity to save themselves all the $$ they can.

Quick Notes:

Remove the...

intake ducting
opti electrical connector behind waterpump
temp sensor connector front of waterpump
plug wire #3 from Opti (2nd from top LHS) (wire loom stud access)
air pump bracket
waterpump - 9/16" X 6pcs (short on sides - stud on LHS for air pump)

quick and easy - perfect DIY

with any luck I will make it back here some time for some additional notes..

I made cardboard gaskets myself and this repair went from a $700 quote to a $5 morning in my laneway - no scraped knuckles

 

Here's a picture I forgot I'd taken - I marked it up - maybe someone will find it useful one day

 

How did you remove the impeller and in which direction did you remove the shaft/bearing?

 

Sorry I couldn't get back to you sooner. It's been too long for me to answer. Maybe if you figured it out you could share it here.

I likely used a hammer and drift on the shaft and backed the impeller or housing up with a socket or old bushing.