The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Is this the right water pump for an L31 Vortec with Vintage AC?

garyd1961 · 10-21-2020, 11:55 AM

The water pump you have now comes back as fitting a 96 to 2000 350 and should be a reverse rotation pump. If it is a reverse rotation pump it will work with a serpentine belt set up but not v belts. The serpentine set up turns backwards compared to the v belt and requires a reverse rotation pump.
Someone mentioned just drill holes in the thermostat and skip the bypass all together. I tried that and it didn't work. It would seem to work at first but on a long drive on a hot day my temperature gauge would go crazy. It would be jumping all over. I put a bypass from the intake through my heater core back to the pump and it's been fine every since. If you don't want a heater you can just loop a hose from the intake to the water pump.

10-21-2020, 11:55 AM	#29
garyd1961 Registered User Join Date: May 2016 Location: Henderson NC Posts: 975	Re: Is this the right water pump for an L31 Vortec with Vintage AC? The water pump you have now comes back as fitting a 96 to 2000 350 and should be a reverse rotation pump. If it is a reverse rotation pump it will work with a serpentine belt set up but not v belts. The serpentine set up turns backwards compared to the v belt and requires a reverse rotation pump. Someone mentioned just drill holes in the thermostat and skip the bypass all together. I tried that and it didn't work. It would seem to work at first but on a long drive on a hot day my temperature gauge would go crazy. It would be jumping all over. I put a bypass from the intake through my heater core back to the pump and it's been fine every since. If you don't want a heater you can just loop a hose from the intake to the water pump.