I see at some point this thread was revived. I have a tricky problem. I have a 97 318 that overheats. I changed the water pump and rad. I don't think it's getting flow and it has a big boule. That is only evident when the fan does not kick on. Thought it was a fan switch but that tested fine. I put it in a pot of water and slowly brought it up to temp. Both temps turned on the the respective circuit. After many hours with the fluke, I found water was not reaching the switch. Some dumb a$$ engineer decided to put it up high in the rad passenger side tank. Well I thought I burped it good enough but it still overheats. At one point it blew the res tank off the rad. Really pissing me off.
I also wondered what this chem test Is. What dou you ask for? Is it litmus paper type of tester? I need to know for sure it's not a blown head gasket or cracked head.