The 2008 Scion Challange
Today, October 26, 2017, I had the opportunity to work on my first Scion. (I came to find out that Scion is made by Toyota). It was blowing clouds of steam out the tailpipe, and the oil was slightly milky, due to coolant contamination. I saw I had my hands full. After fully inspecting the cooling system, I found that everything was working properly.
So what caused the head gasket to blow? I went ahead and treated the system with HGR-12 and was again rewarded with a smoother running engine, and no more steam out the back. After allowing the engine to run a good half hour, the mystery about what caused the head gasket problem was solved. I suspected the radiator cap was bad when I did the inspection, but it wasn't until I squeezed the top radiator hose, which should have had some pressure build up, and and should have resisted squeezing a bit that it hit me. There should have been pressure naturally, (that is what a hot cooling system does, builds up a bit of pressure, but there was no pressure at all. The problem turned out to be that radiator cap. It was NOT holding pressure. Yes, a 10 dollar part can cause a very costly engine problem. Fortunately for this Scion owner, however, HGR-12 solved his problem, along with a new cap!