this is a question that my son asked me today. he took the cam cover off his bmw m3 to do some other work to his car, and found half his camshaft was blue on the inlet side. the other side was silver as it should be. this indicates over heating i think. i know this is not a zx question but it could relate to most cars i guess. questions? what could be the possible cause that this could happen. and could this weaken his cam shaft in the future. i know this is a question that maybe hard to answer not seeing the problem first hand but any ideas would be welcome. many thanks bigmax.
is it a blue paint, or is it the blue that metal gets when heated and cooled? Might be some sort of BMW coating to prevent wear, like electro-hardening or whatever it is called (think of the teeth on some wood saws). If the engine was cooked so bad that the camshaft was blue, then I think there would be more obvious issues (holes in pistons, for example).
re cam shaft its not blue paint. as for a hardening metal process, if this was the case then all the cam shaft would be all the same colour. its only on the the last bank of cylinders that are blue.cant get pics at this moment.
I'm not familiar with an M3 camshaft, but my guess would be that this discolouration is localised near one(or more)camshaft bearings, which would indicate that the bearing fit was too tight(or lacking lubrication)and has caused severe overheating.
BMW heat-treated the crank on the S54 M3 engine, it wouldn't surprise me if they did the cams too. If he looks at his crankshaft, it should be blue as well.
Not too sure what you mean but normally camshafts are not blue even if hardened so there may be a lack of lubrication. Which should be fairly obvious on inspection. What about the cam followers?
