Water Pump ID Please

[Bill #34162]

Curious as what this pump was originally intended for. On top it says GM13. Below that is 3839175. Below and to the left of that is the letter S. On the drivers side is J84 (November of 84 build date?). Thaks as always for the help.

[Joe L.]

Re: Water Pump ID Please

Bill------

The GM #3839175 water pump casting was kind of an "oddball" casting that was used on Corvette small blocks with external bypass (i.e. 365, 375 hp) during 1963 and 1964. It was used alternately to the much more widely used GM #3859326. Both pumps have the large boss on the top for the external bypass which was drilled and tapped for a 1/2" NPT fitting during these years.

I don't think that these pumps were usually dated, but your "J84" sure looks like a date code. If so, it's likely 1964; I think that these pumps were out of production long before 1974.

As far as passenger cars go, this pump was only used on Corvettes. However, I think that there were likely truck applications for it, as well.

[Bill #34162]

Re: Water Pump ID Please

Thanks Joe. I was right on one account, its not right for my 70 small block. Sounds like it might be a hard to find piece. It works fine on the car now, but I hope to swap it one day for the correct one. By the way, what is the correct one?

[Joe L.]

Re: Water Pump ID Please

Bill-----

For some reason, these '175' pump castings seem to be not as rare as I'd expect them to be. Since, as I mentioned, for passenger cars they were used only on SOME 63 and 64 Corvettes with L-76 and L-84 engines, from that standpoint that ought to be quite rare. However, I do think that they were likely widely used in trucks.

As far as your 70 small block pump is concerned, ALL 1970 Corvette small blocks used the GM #3782608 casting which were dated since 1964. This casting has no large, upper drilled and tapped boss for external bypass. Internal bypass is used.

[Bill#34162]

Thanks Joe *NM*