The Original 1963 & 1964 Water Pumps Were Aluminum

[Jason Edge]

I saw this question over on the CLC forum and thought reposting and consolidating my findings here on our site. I had posted this as a reply before but will repost and tag it and save to our Help Page.  Note, I am not trying to debate which is better just stating facts of what came on the cars from the factory. Here is the info I had posted:

Literature descriptions of the New for 1963 390 engine, the Serviceman Bulletin, and the 1963 & 1964 shop manuals, all refer to an aluminum water pump.  My best guess is at some point they switched to the cast iron casting (which some prefer), and perhaps alternated between aluminum and cast  iron.  Just to note, I have personally never had any issues with the aluminum water pumps.  I've had an aluminum one on mine since I bought it since 1996 and remember maybe having to replace it once 10+ years ago.

For reference if you look at the 1962 October Serviceman bulletin page 48 it says "A new die-cast aluminum water pump, which is serviced as an assembly only". There is a scan on the 63/64 site at this link: https://6364cadillac.ning.com/photo/1962-pg-48-oct?context=album&am...
Click 'View Full Size' and the + in the magnifier to view full size.

The 1963 shop manual refers to a 'die cast aluminum water pump on page 11-1.
The 1964 shop manual refers to a 'die cast aluminum water pump on page 7-1.

I have also seen it listed in other early literature such as the Dealer Data Books (see page 88A in the 1963 Dealer data book), so am pretty sure that from the factory they were aluminum.

[Bill Wolf]

I recently had to replace my water pump on my 63 SDV which I believe is original because the hose had the three ripples along the one side. BTW, this pump was cast iron. Well, taking it off, one of the 1/4" and one of the 3/8" bolts broke off as well as both thermostat housing cap screws. I had to drill them out and retap them. What I did to make sure I was centered was to tap the flange of the OLD water pump 7/16-14 for the 3/8" bolt and 5/16-18 for the 1/4" bolt. The 3/8" bolts are 3 1/2" long and there was 2" of the bolt stuck in the timing chain cover. I bolted the old water pump back. I drilled thru the center a 7/16-14 bolt and a 5/16-18 bolt and screwed them in as far as they would go and used them as pilots to start drilling out the broken bolts. After I drilled the pilots, I was able to drill out the 1/4" with the tap drill (#7 bit) and retap 1/4-20.. For the 3/8" bolt, I drilled out  three 7/16" bolts 1/8". 1/4" and tap drill 5/16". Once I drilled the 5/16" deep enough, I removed the 7/16 bolt and used a 3/8" bit to drill out the remainder of the bolt in the timing chain cover. Fortunately, I have a long enough 3/8-16 tap to clean out the remainder of the broken bolt. i was not prepared to do all the work to remove the timing chain cover.