The circlip is removed when disassembling the pump. Blue posted a video a while back about rebuilding water pumps. The mechanic shows it in that video

Here's an informative video I found while looking for Blue's.  Couldn't find his.  

I have an old leaking pump but it doesn't have the spring clip.  9011-12 is the number on it.  Don't know if it's Nissan or aftermarket.

https://www.youtube.com/watch?v=U1x3-R2l03Q

 

Check this out.  Zoom in and you can see the spring clip.  There must be something out there for the L24, 26 and 28.  Hard to beat $20 for a fresh AZ pump though.

http://www.ebay.com/itm/Water-Pump-Rebuild-Kit-FOR-Nissan-Datsun-1600-Bluebird-P510-L13-L16-1967-Onwards-/281852998385

 

Friend of mine says made in China junk. Think I will be packing spare (to go along with my ECU and Ign module). Its a pretty simple device so not sure what would make it poor quality unless its just low quality bearings/seals or bad QC of the finished good.

New to the car game, did some research on the old interweb, yikes a LOT of talk about water pumps, country of origin, QC, you name it there is several opinions going in several directions.

Anyway I will report back on how THIS water pump works out so I can add to the chorus of noise.

 

Edited October 11, 20168 yr by Dave WM

I discussed it with my friend some more, he says I should be ok going aftermarket considering how little I drive it. I have NO exp with aftermarket pumps, but I have to assume Nissan no longer supports something this old.

You mentioned your concern about snapping a retaining bolt during the process of removing the water pump.  As I remember those bolts are pretty small and buried in the block.  I've had my Z 40 plus years and over thirty years ago had to replace the water pump.  Yeah, one of the bolts snapped off!  There was no way I was going to be able to extract the bolt so I thought what the hell I'll give it a shot and replace the pump minus one bolt.  Well guess what?  All these years and she has never leaked.  Another one of the reasons I love my Z!

Similar story here except for the time since replacement, I snapped a bolt on my Z's water pump when replacing it a few years ago and have been driving it all over, no leaks.  I put anti seize on the bolt threads when they went back in (can't remember if I used new bolts).

Edited October 12, 20168 yr by Mikes Z car

that snapping is what I kept reading about, I got lucky they came out easy, and I did use anti seize for replacement. Only odd thing was the locating dowel holes on the AZ pump were oversized, so the dowels did not really locate it. I guess there could be an issue with the fitment of the vanes to the cover, but it all worked ok.