I was working on my 2000 Chevrolet S10 pickup and had to drain the system of all the coolant. Changed all hoses out and flushed heater core. And that's a 2.2 l engine with 175,000 mi. Has automatic transmission. Uses the Dex cool. I put about seven quarts in what I thought was an empty system and that's all it's taking maybe eight and a half quarts and I read the shop manual which says it takes 11.5 quarts. So I'm really confused. Why isn't it taking any more coolant? Is there an area that's maybe plugged now inside the engine? I thought it took a significant chunk of debris to clog the engine. And I did fill the overflow tank. I poured fluid in through the heater hose into the engine. I pour fluid into the radiator itself to allowed to drain into the lower hose. And I added some to the overflow tank to let it drain backwards into the overflow pipe or hose. So why isn't it taking almost 3 gallons like it should?