The automotive machine shop who is working on my Corolla head and block said that one of the valves was severely burnt. What causes burnt valves???
Usually a poor fuel/air mixture... running too lean etc... sometimes faulty timing can aggravate the issue as well. Exhaust problems are known to cause this issue in some cases... but so you know, there is a multitude of ways to burn a valve. FYI - Just replacing the valve will not fix the underlying issue... you will end up with the same problem. Once done, you need to start with your fuel and intake mixtures. - Good Luck!
This Site Might Help You. RE: What causes burnt valves? The automotive machine shop who is working on my Corolla head and block said that one of the valves was severely burnt. What causes burnt valves??
Several things, the most common being too much heat in the combustion chambers. The heat literally melts slots in the valve face-I had one from 4.9 Ford truck with a clogged radiator that made the valve look like a sand dollar. Anything causing it to run hot , or hotter than designed, needs to be addressed. The other common problem is opening the exhaust up TOO much-Exhaust valves(which, by the way, are the ones that burn 95% of the time), are designed to have exhaust system backpressure help seat them when they close, thereby transferring the maximum amount of heat from the valve face onto the valve seat, which cools them down before the next cycle. Taking off converters, and staight-piping the exhaust will almost always result in burnt valves. An inoperative EGR system, which by design lowers the combustion chamber temperature , can contribute to valves burning.Overheating , however, is the most common cause.
I was told that burned valves resulted from a poor machining job. By the way, I also have a Toyota. Hmmmmm. The car had all the valves replaced and the head gasket as well with only 12,000 miles on it.
