Hot spots in a motor

[moribundman]

Sump temperatures are not really indicative of what temperatures occur in the various lubricated components of a motor. I presume cam lobes and valve tappets, exhaust valves, and piston rings see the highest temperatures? Does anybody have any specific figures?

 

[John K]

I don't, but recall that articles about the Toyota engine sludge issue talked about temperature differences contributing to sludge and some parts of the head were reaching 260F whereas previous Toyota engines heads reached only 230F? They said the head coolant passages were changed to raise head temps to improve emissions.........

 

[Curious Kid]

Here's a link that points to thermal contributing sources...

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000196

 

[moribundman]

Curious Kid, thanks for the link, but that post still doesn't answer my question. While the post addresses energy transfer from components and their contribution to sump temperature, it doesn't mention what actual temperatures are encountered.