Water pump dates - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**l79m20** · 06-12-2009, 08:56 AM

Am just finished changing out my water pump for a 250 cu and am wondering if the pump taken off is the original one to the truck, I am second owner. On the front of the pump is cast into pump GM7 and the casting numner on the pump just above it is 3788478. What I assume is a build date for the casting is a circle with an m in the center then G309 another circle with a 1 in the center. Can any decode this for me and do i have the original pump, will save it to be rebuilt at some other time. Any thoughts? This is a great site!!!!.............................Kirby

502tripower · 06-12-2009, 12:25 PM

Quote:

Originally Posted by l79m20

Am just finished changing out my water pump for a 250 cu and am wondering if the pump taken off is the original one to the truck, I am second owner. On the front of the pump is cast into pump GM7 and the casting numner on the pump just above it is 3788478. What I assume is a build date for the casting is a circle with an m in the center then G309 another circle with a 1 in the center. Can any decode this for me and do i have the original pump, will save it to be rebuilt at some other time. Any thoughts? This is a great site!!!!.............................Kirby

Kirby, You don't say what year your truck is but the date code G309 would most likley be as follows. G=July 30=day 9=year

Here is an example.

502tripower · 06-12-2009, 12:32 PM

I looks like maybe your 0 might be a 6. In which case the day would be 3 and the year would be 69. Take another look. In most cases the last two digits represent the year.

**l79m20** · 06-13-2009, 03:48 PM

My truck is a 1966 so this does not look to be the original to the truck.........Thanks for helping with the dates though, useful info.........Cheers...Kirby

06-12-2009, 08:56 AM	#1
l79m20 Registered User Join Date: May 2005 Location: Reading, Kansas Posts: 628	Water pump dates Am just finished changing out my water pump for a 250 cu and am wondering if the pump taken off is the original one to the truck, I am second owner. On the front of the pump is cast into pump GM7 and the casting numner on the pump just above it is 3788478. What I assume is a build date for the casting is a circle with an m in the center then G309 another circle with a 1 in the center. Can any decode this for me and do i have the original pump, will save it to be rebuilt at some other time. Any thoughts? This is a great site!!!!.............................Kirby

06-12-2009, 12:32 PM	#3
502tripower Registered User Join Date: Jan 2008 Location: Satsop, WA Posts: 606	Re: Water pump dates I looks like maybe your 0 might be a 6. In which case the day would be 3 and the year would be 69. Take another look. In most cases the last two digits represent the year. __________________ 1963' Chev Custom Cab 502, 67' 435hp 3X2 intake, 9" 4:30 Posi 1961 Impala SS 348/350 4-speed 3:70 Posi 1961 Bel-Air Bubble Top 283 Turboglide soon to have a 348 3X2 4-speed 1950 17' Fairliner twin cockpit barrel stern 312 Y block 1X1 intake Borg Warner 1:1 gear 1957 Fleetform 14' twin cockpit barrel stern 1969 BP-125 Merc 1949 Transitier 3-wheel forklift Crosley 4-Banger 98' FXD 2002 2500HD

06-13-2009, 03:48 PM	#4
l79m20 Registered User Join Date: May 2005 Location: Reading, Kansas Posts: 628	Re: Water pump dates My truck is a 1966 so this does not look to be the original to the truck.........Thanks for helping with the dates though, useful info.........Cheers...Kirby Last edited by l79m20; 06-13-2009 at 03:49 PM.



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