Mike Blondin

Ok, I know this is an old post and there are videos showing how to add coolant to the lower part of the tank to resolve this issue. I wanted to clear this up for everyone. Gm knows they have a problem with the sensor in the tank and they should own up to the problem. How ever its not a safety concern for a recall. The gm part number for the tank is 084257137 I paid $93.71 for the tank and I also bought a new cap 084148294 left hand thread. Paid $10.05 for the cap. if the cap is over tightened it may break. There are a few videos out there where people are filling the lower tank. Please do not do this! The lower tank is the expansion tank and it is designed to fill up when the upper tank gets to high on pressure and fluid. The coolant flows across the top and into the lower tank. When that coolant is needed it will be sucked back up to the top tank. If you fill the lower tank it will spew out all over the tray around the tank and make you think you have a coolant leak. Just top off the top tank Only! Changing out the tank is a 25 minute Job. Disconnect both negative cables at each battery. Remove the air box and battery in front of the tank. You will have to disconnect the 2 blue connectors and 2 cables from the power distribution block on top of the battery. This will gain you access to the 10mm bolt on the bottom of the Tank. Pull forward and tank will pop out. pinch off 2" hose to the side of the tank and remove clamp and pull hose. There is a 3/4 hose to a nipple on the top of the tank that will need to come off. Rinse coolant off the tray from the hoses being removed from the tank. Install new tank. Then install hoses. Fill top tank to fill line. Install battery and air box. Connect both battery cables and start the truck. Have someone bring idle up to 2000 rpms for 5 minutes to burp all the air out! Add coolant if needed to the full arrows. Install the cap. Light should be off now.