Originally Posted By: 4wheeldog
Coolant, when concentrated enough, and sprayed on a hot surface, is very flammable. I saw it happen once, maybe 30 years ago. Stuck in a construction zone stop up, and the guy behind me was in a pickup with both a camper and pulling a trailer. Maybe 100 degrees out. While we were sitting waiting, he had his engine running. First there was a burst of steam, then smoke and flame!
I had a fire extinguisher and so did he.....It took both of them. When we got it out, and the hood up, the upper radiator hose had let go, and coolant was spraying onto the exhaust manifold. In conversation, he admitted he ran 100% coolant.
Before that, I used to run 60 to 70% coolant, so top ups would not be a problem. Since, I have been meticulous about keeping it at 50%.
30 years ago would have probably been Ethylene glycol, which does have a flash point in the mid 230's. So that does make sense, straight coolant, hot manifold....