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Old 12-07-2012, 08:27 PM   #20
Airhead Wrangler
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Joined: Mar 2008
Location: Back in Seattle, FINALLY
Oddometer: 6,552
Originally Posted by mattcfish View Post
Obviously, let me clarify, a good oil pump will produce more pressure than a warn out one when hot. 50 lbs of pressure at 300F has to be better than 10Lbs at 300F or 10Lbs at 180F for that matter....right?
At some point the oil is just too hot no matter what pressure it's at. I just want to know how hot that is?
Or is it that the expansion of some internal parts will become so great that no amount of lubrication will prevent seisure?
Your most critical bearings, mains and big ends, depend on an oil film to prevent metal on metal contact. As your oil gets hotter and loses viscosity it loses it's ability to resist the pressure of a rod being forced into a crank journal by combustion pressure. At what exact temperature this occurs depends on your oil formulation and how much load the engine is under. I won't even venture a guess because I have no idea. No amount of oil pressure will prevent this if the oil is not viscous enough.
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