Whats TO HOT FOR OIL TEMP

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06-28-2014 | 09:17 AM

#51

MILD THUNDER

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Joined: Jul 2004

Posts: 11,332

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From: chicago

Quote:

Originally Posted by SB

Something that doesn't get mentioned much, if at all, as everyone worries about oil viscosity thinning as the oil get's hotter is: valvespring pressure. As a spring get's hotter, the psi lessens. Springs create a lot of heat and oil is used to cool them.

Edit in: See Page 17 of the following;
http://www.racingsprings.com/Multime...b/kb513102.pdf

Absolutely. Like I said earlier , there's more to the story for oil temperature than what a "oil guy" states the fluid can safely withstand. Their are other things to consider and valve spring cooling is one of them for sure .

I wonder how many engines are out there running around with high oil temps, blaming it on cooler size, when in fact their valve spring setup is poorly matched and the springs are surging like crazy making a ton of heat to the oil. All you ever read on hear about valve spring choice is "seat pressure ". Nobody cares about the rate of the spring or the physical dimensions in reference to coil bind.

Either way, I would not setup an endurance marine performance engine to consistently see 240, 250, 300 degree sump temps. Just my opinion.

06-28-2014 | 02:45 PM

#52

Borgie

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Joined: Jun 2013

Posts: 1,014

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From: AZ

Quote:

Originally Posted by bobl

Let me see if I can add to the confusion. Most mercury applications are measuring temps after the cooler as it enters the block. That would explain why they want a relatively low temperature, it's a lot hotter in the pan. A couple of posters mention they were measuring temp before the cooler, hence they get a higher number. If you compare the temp reading on the gauge to that of a gun you quite often see a large difference. Where are you reading with the gun? Pan or filter before the oil is cooled perhaps? Gauge isn't wrong. It's reading cooled oil. Just more food for thought...carry on.

Bob Lloyd
Full Throttle Marine

Very good point bob. IMO oil should hit 212 as it's designed to operate at said temp regardless of what merc or any other person or company wants to believe. If the oil cooler is large enough you should be staying in the safe temp zone even on full throttle runs. I know the 525 has been used here to show what merc has used in the past, however they are obviously doing things different today and it's merely one of many different ways to skin a cat.

Last edited by Borgie; 06-28-2014 at 05:55 PM.