Status update - after starting the cold engine, slowly poured the 16oz bottle of Blue Devil Head Gasket Sealer into the radiator. Topped off the radiator and the overflow bottle. Ran the car, at 10 minutes I got white smoke from the engine. At 20 minutes, the smoke was noticeably less. I gunned the engine and noticed that while it was running rough, it did not feel like a misfire. At 30 minutes I noticed water coming out of the overflow tube into a catch pan I placed there. I have a 180°F thermostat, using a laser temp gun I saw 193°F at the housing, dashboard gauge was at the M in NORMAL. Waited a few minutes, then shut the engine down. Soon after I shut the engine down I got a lot of steam out of the radiator cap. I put on some gloves and pulled the pressure relief valve to relive the pressure. I lost maybe 3/4 of a gallon.
Called the Blue Devil support line, who has told me to wait until the engine has cooled, then start it up. He told me the product works by temperature differential, so the engineer in me tells me it's impossible to clog up the coolant system. I was only able to put in half of what was in the catch pan into the radiator
When my laser told me the engine was at 133°F I started the car. Engine ran well, steam was barely noticeable. The dashboard temp gauge creeped up dangerously to just below the M, then fell back down to below the L (this is common from BD success stories). The gauge also jumped a lot which is a sign of low coolant. So I let it run for ten minutes then shut it off so I could wait for it to cool so I could add the rest of the runoff coolant.
30 minutes later I let the radiator pressure go with the pressure relief valve on the radiator cap, then I added almost all of the runoff coolant to the radiator and the overflow bottle. Started the car and idled for 15 minutes. Shut it off when the temp gauge got near the M. The steam from the head gasket leak is almost unnoticeable unless you are looking for it. The drip, which used to be one drop every 5 seconds, is now one drop every 20 seconds. No water from the tailpipes.
CONCLUSION SO FAR: Although incomplete, I tentatively call this a success. The car has not idled long enough for the product to completely work. However the car runs much better, the steam is barely noticeable. I'm burning a vacation day today so I can occasionally idle the car. Glad I have a 3-day weekend.
I do have the disadvantage of having to contend with the Texas heat, which will be in the 90's today. But at this stage, I tentatively call this a success. I expect the leak to be completely healed after enough idling.
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