Alen Domelian

Hi, guys im new to the site and have interesting issues trying to figure out my 05. I had a heater hose go bad and was leaking, and I decided it's best time to do new hoses and thermostat with all ac Delco as I always do on all my cars with no issues and replace the temp switch as well and water pump. I have always done this job many times on all my previous tahoes and escalades and suburban's since 1999 with no issues. I finished the job filled the coolant from the radiator hose, removed from the top until full to the mark as well as the radiator full and hooked up the hose, then back ran the heater and looked to see if any bubbles would come out to bleed, and it was fine. I installed a new cap as well, and the car was fine. Drove it a couple of days, and their wife called and said the car surge tank is bubbling and boiling water is coming out of the excessive hose, which I thought maybe I put much coolant, but then I inspected it, and it was fine. The gauge didn't overheat, but most of the water came out of the tank. When I opened the cap, there was no pressure or a hiss, so I out mire coolant and ran the car with the cap open to bleed the system. It took in all the water, and I turned off the heater and rand the car at idle with the cap open, and after 10 to 15 min, the surge tank boiled. Water came up and then quickly back down, which seemed weird like there was a blockage, and now it was ok, so I put the cap on and ran the car the same thing the surge tank boiled and bubbled water shot out of the access line in the fender. I don't know if it could be a bad radiator clogged or heater core or surge tank. I never had this issue, and I don't smell coolant inside the car or see fogged up windows

hanky

One way to go on this would be to do a combustion gas check at the recovery bottle . If compression is managing to get into the cooling system that would confirm it.
It may not be enough to cause an overheat condition, but still allow a small amount of compression to get in there. Depending on what result you get will determine where you go from there.

Alen Domelian

could it be a partially clogged radiator. I didn't a block test so fat it was ok