my 2001 gmc / 5.3 has an antifreeze leak.

Pressure test!

ok I will pressure test. 1st time I've ever tried doing forum. thanks

You are welcom, i don't see the connection with the evap. canister either.

Hi you all. I'm also having problem with coolant leak in my 2001 GMC 1500 Sierra. The cooling system pressure has been tested and it was found OK (15PSI). The light comes on (coolant low level) every 100 miles driven. I' ve read at AA1CAR.COM that some GMC V8 are notorious for leaky intake manifold gaskets. Is that true? The truck spent about 1 hour at the mechanic. What did they miss? The water pump has been replaced on 12/2011.Thanks a lot.

How long was the 15psi applied? May take an hour or more on a warm engine to show up. Uv sensitive dye is also useful.

Thanks for the reply. I'm going to check the intake manifold this weekend. This engine has a radiator hose from the radiator going to the throttle body. Could there be a leak in the throttle body. ??? What is this line for. I figure it heats the throttle body so ice crystals don't form. I have been told to check the charcoal canister. I have no idea why that has anything to do with the coolant leak. ???