water pump date code

[Gary P.]

what date would a code G-1-5 be? can't find any water pump reference in my specifications guide
thanks

[Joe L.]

Re: water pump date code

Gary----

"G-1-5" would indicate a July 1, 1955, 1965, 1975, 1985, or 1995. Depending upon the casting number, it could narrow down the year possibilities.

[Loren L.]

No dates in 1955 *NM*

[Robert Willis]

Re: water pump date code

The 55 and 56 pumps for the 265s had a 3/8s pipe thread for the heater hose. In 57 they were enlarged to 1/2 inch pipe thread. If the pump has a 1/2 inch thread it must be 65 or ??? I have had 55 pumps (passenger car) that were date coded .

[Gary P.]

Re: water pump date code

The casting # is 3856284. This came up for sale on Ebay as being for an early 66 and I just wasn't sure on the date code. Would have been too early for my car (5810).
Thanks for answering my questions guys
Gary

[Dan Pepper]

Re: water pump date code

Gary-

The number signifies that the water pump is for a big block, either the 390hp or 425hp engine.

[Joe L.]

Re: No dates in 1955

Loren-----

1955 Corvette water pumps usually were not dated, but other 1955 water pumps were dated. Truck water pumps, for example, were usually dated.

[Loren L.]

Can you tell me how the water pump

manufacturer knew which of his pumps was going on a Corvette and which was going on a truck, so he knew which should be dated? Why also does the entry in the 1956 Parts Book read:
"55 ALL, 8 cyl (exc H.T)....(cast 3704911-less fan pulley)..3704906..11.25"

(H.T. = Hydramatic Transmission)

[Jack H.]

Couple of tidbits....

First the casting number on the main housing is just that (a casting number). The secondary operations (E.g. drilling and tapping the upper boss for an external bypass, selecting/installing impeller drive shaft bearing/seal and press fitting the appropriate hub) turned the raw casting into a discrete final GM specific PN intended for specfic operation.

GM had more than one foundry site for castings. Saginaw foundry facilities generally supplied the Flint engine plant. Tonawanda, NY was both a foundry and assy facility. There was also St. Katherine's in Canada.... The 'typical' sequence was for Saginaw/Flint to supply SB Corvette parts to St. Louis and Tonawanda to supply BB Corvette parts (there are known exceptions).

At times, BOTH Saginaw/Flint and Tonawanda turned out 'equivalent' SB castings and this IS true of certain water pumps. Differences can be seen in the equivalent Saginaw/Flint vs. Tonawanda version of the same casting (size, placement of cast number font, the presense/absense of a 'T' emboss indicating Tonawanda source, whether or not there are reinforcing ribs on a particular casting, and the manner of date coding). On Tonawanda cast water pumps, from the late '50/early '60 era, I've noticed the presense of reinforcing ribs NOT present on the equivalent Saginaw/Flint casting, that Tonawanda adopted date coding for water pump housings MUCH earlier than Saginaw/Flint (earliest I've seen in 1960 vs. Saginaw/Flint beginning to date their SB pump housing castings somewhere in the '65 era) and the fact that Tonawanda used a 2-digit sequence for the year while Saginaw/Flint kept a single year digit sequence ('60' vs. '0').

I've never seen a Tonawanda issued 3704911 water pump casting either '55 version without upper boss for bypass or '56 version with the upper boss. I have seen both Saginaw/Flint and Tonawanda issued 3736493 SB water pumps. The Tonawanda versions sported reinforcing ribs and date coding where the Saginaw/Flint equivalents lacked the ribs and lacked date codes. Similar comments on the 3782608 and 3782609 pump housing castings with the exception Saginaw/Flint casts began to bear date code emboss in the '65 era.

[Craig S.]

Tidbit questions....

Jack - thx for the insight. The P/N 3856284 big block pump being discussed has a one year date code vs two, so does my recently purchased unit for my 66 with an A 8 6 date. This seems counter to your Tonawanda practice of using two digits for the year of manufacture, I would be surprised if these BB pumps were cast anywhere other than Tonawanda....thoughts? Thx, Craig

[Joe L.]

Re: Can you tell me how the water pump

Loren-----

Water pumps of the same casting number may have been sourced differently. For example, some may have been manufactured at Flint, some at Tonawanda, and some elsewhere. Flint was producing engines for Corvettes and most other Chevrolet cars. Tonawanda MAY have produced engines for trucks. So, Saginaw-cast pumps (e.g. without dates) could have been used on Flint engines and Tonawanda-cast pumps (e.g. with dates) could have been used on Tonawanda manufactured engines.

Another scenario is this: the PRODUCTION pumps used by either Flint or Tonawanda may have been different than the SERVICE pumps available, even though all carried the same casting number. The SERVICE part number is not necessarily the same as the PRODUCTION part number or, if the SERVICE part number was also used in PRODUCTION, not necessarily the ONLY part number used in PRODUCTION. One source may have provided the castings for the build-up of the pumps used on Corvettes and/or other Chevrolet cars and another may have been used for the build-up of pumps used on, for example, trucks or other Chevrolet cars. In 1955 there is a strong possibility that some foundry besides either Saginaw or Tonawanda was producing water pump castings. This may have included another GM foundry (like Defiance, OH, Danville(Tilton), IL, or St. Catherines, ONT) or an outside foundry. Each would have included the casting number, but may have had different practices for dating. The castings and/or finished waterpumps did not necessarily go into a "hopper" to be drawn out randomly and installed on engines randomly.

Those are just 2 of the possible scenarios that could have resulted in the differences in dating seen on Corvettes and other cars. Also, and as far as I know, no one has ever been able to absolutely establish that NO 1955 Corvette waterpump was dated OR that ALL 1955 truck waterpumps were dated.

[Joe L.]

Re: Tidbit questions....

Craig-----

Contrary to popular opinion, Tonawanda-cast parts do NOT exclusively use the "two digit" year code. Quite the contrary, I've seen many Tonawanda cast parts that used the "one digit" year coding system.

As far as I know, all '284' waterpump castings were cast at Tonawanda. The foundry in Tonawanda was shut down in 1984 and, after that time, most big block castings were produced at Defiance, OH. However, production of the '284' waterpump casting ended in 1969.

[Jack H.]

Re: Tidbit questions....

Original post in the thread addressed SB water pump castings. I will agree that I've never seen a 3856284 BB pump that wasn't cast at Tonawanda and I've never seen one with a 2-digit year code. In fact the original '6284 on my L78 is quite clearly dated 'B 25 5'.... Point is the thread started with SB pumps from the 55-57 era and I was giving 'tidbits' about those. Last, just because I haven't 'seen' this/that doesn't mean it's not true or didn't happen, heck I learn something new all the time, guys!

[Craig S.]

Re: Tidbit questions....

Thx Joe and Jack....just trying to learn!....great input...Craig

[John H.]

Re: Tidbit questions....

Just to keep things interesting, I "liberated" a 3782608 pump from a rebuilder's stock yesterday that has a "T" ahead of the "GM2" pattern number, and it has a "D 6 7" single-digit year code. There are few "absolutes"