Maybe I am in denial. I just did the crossover and part of me feels like the problem stems from that and is not the HG. I just did the test again, it seems like there is some color change but maybe more green than yellow. If it is the HG, would it being going back and forth with the engine temperature. Today when I was driving home, the temp jumped up two notches; then just as fast as it rose, it went back to normal operating temp. It is building a lot of pressure under the cap though. I relieve the pressure, it is fine. I also just did the test on the purge line, it is sputtering.
To recap...
Mid Feb - loose coolant from failed crossover gasket. I see the leak at the back of the engine.
Mid Feb - Add six tablets to the hose going to the water pump. The leak immediately stops. I do not hear any air and am hoping to make it to warm weather so I can repair.
Late Feb - Everything is still working just like it should. No problems.
March 1st week - I drive an hour. While stuck in traffic I notice that the temp sometimes jumps up on notch and then goes back. It will run for 20 minutes before seeing the problem again. No air in system.
March 2nd week - The seal fails and I loose coolant while pulling into my driveway. I have a nice two days to work on it and I replace the cross over gaskets.
March 3rd week - I still hear the air in the system and very rarely I see the temp jump up one notch and then back down.
April 1st week - Engine gets really hot, almost hits the red. Lots of pressure. Once pressure is relived it goes back down to normal and I can drive without problem for a few days.
April 2nd week - Replace radiator cap. I thought it was helping but I still hear water in the system.
Today - Temp goes up two notches and then falls back down to normal halfway into a 15 minute drive home. It didn't have any problems on the way into work. I was going on the back roads and up hills when it happened. I drove to work on the highway.
- The purge line is sputtering a bit and the block test changed color a bit. Not as yellow as when I put the tester up to the exhaust pipes.