Oil Cooler

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Paul Crips
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Oil Cooler

#1 Post by Paul Crips »

I know this been discussed a bunch of times but I want to install an external oil cooler and a full flow oil filter on my C engine. What is the best option? I have been a registry member since 1978 and know there is a lot of technical articles about this but would appreciate any updates that might include new technology. Just interested in preserving my engine and want to take a road trip this summer with my beloved C.
Paul

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Ron LaDow
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Re: Oil Cooler

#2 Post by Ron LaDow »

Paul,
Before you go through the effort, are you sure you need an external cooler? Cs shouldn't run hot.
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Paul Crips
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Re: Oil Cooler

#3 Post by Paul Crips »

My oil temp gauge shows the engine is running hot when it's hot outside. I run Shell Rotella oil because of the zinc additive. Could it be that I have a bad oil temp sensor?

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Ron LaDow
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Re: Oil Cooler

#4 Post by Ron LaDow »

I'd definitely confirm the gauge and also see what might be the problem if it is hot. It really shouldn't be if all's right with the world.
A full-flow on its own will reduce temps (the Pre Mat part knocks ~10% off) and might save you the additional cost, effort and holes in your car required by a cooler.
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Mark Roth
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Re: Oil Cooler

#5 Post by Mark Roth »

How hot is hot?
Mark Roth
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Cliff Hanson
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Re: Oil Cooler

#6 Post by Cliff Hanson »

You could install an aluminum oil cooler for better heat rejection and if you have an electric tach go with the Precision Matters full flow filter. If a mechanical tach then possibly mount a remote filter in the left fender well. You should have plenty of cooling either way.
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Thomas Sottile
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Re: Oil Cooler

#7 Post by Thomas Sottile »

What king of mileage do you have on the motor, is your advance correct? are you running lean? My SC run just fine in hot weather 90 plus 75 MPH all day long. with a stock cooler. most extreme temp is 210F MY OIL TEMP GAUGE IS IN NUMBERS. Stay cool Tom

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Greg Bryan
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Re: Oil Cooler

#8 Post by Greg Bryan »

Back when my 912 was a daily driver, it was running on the hot side - I rightly assumed that it was a buildup of dirt inside the engine sheet metal. Removed the engine and all the tin, cleaned everything and put it back together and it ran visibly cooler on the gauge.
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Dave Wildrick
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Re: Oil Cooler

#9 Post by Dave Wildrick »

Paul Crips wrote:My oil temp gauge shows the engine is running hot when it's hot outside. I run Shell Rotella oil because of the zinc additive. Could it be that I have a bad oil temp sensor?
According to electrical guru Joe Leoni, if you have an original temp sending unit (6 volt), a volt/ohm meter should show a resistance of 28 ohms at room temperature (74 degrees F.).

If your gauge has been recalibrated to work with the new modern senders (and you don't have the original sender), maybe someone else knows what the reisistance should be.
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Al Zim
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Re: Oil Cooler

#10 Post by Al Zim »

HOW HOT IS HOT? One thing is for certain you cannot trust a 50 year old gauge and sending unit to tell you the truth. Go to harbor depot and purchase an electronic temperature checking device that does it by infra red. Drive the car hard on a hot day then stop by the side of the road and measure the temperature of the side of the engine case on the aluminum. That will tell you what the true temperature is. I believe that the oil will cool down 20 or so degrees as it passes through the cooler into the bearings. If your case temperature is 250 the oil is 230 to the bearings which is only 18 degrees above what it takes to burn the water borne impurities out of the oil.
I would like to caution you about fast driving in 356 cars. The original chassis design was from before WWII. When the cars were manufactured the highway speeds in the U.S. were seldom over 65 MPH. 356 vehicles have no built in safety factors without a shoulder harness you can be impaled on the steering column with enough force to kill you. al zim Copyrighted 2014 all rights reserved.
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Brian R Adams
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Re: Oil Cooler

#11 Post by Brian R Adams »

Al Zim wrote:If your case temperature is 250 the oil is 230 to the bearings which is only 18 degrees above what it takes to burn the water borne impurities out of the oil.
I have struggle to even get my sump temperature that hot in winter. (Boiling point of water is actually lower than 212 f at my altitude - around 203 f.)

I not sure the boiling point of water is really required. In Lycoming's literature they state something like 165 f is hot enough, if sustained for a reasonable time. I personally get it to at least 185 f which is the sump temp (as determined by a Mainely dipstick and an IR sensor) when my Palo Alto-massaged gauge/sender combo puts the needle just into the green.

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Brian R Adams
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Re: Oil Cooler

#12 Post by Brian R Adams »

PS

I suppose I was thinking of this declaration from a Textron/Lycoming Service Instruction (viewable online):

"For maximum service life, maintain the following recommended limits for continuous cruise operation: ... Oil temperature - 165°F. - 220°F."

Elsewhere, in a more complete document I cannot find just now, I recall the minimum operating temperature was explained in terms of purging volatile oil impurities.

Brian
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Re: Oil Cooler

#13 Post by Mike Horton »

Brian, I have always used as a "hot" oil temp limit, proper gauge calibrations assumed, the high limit in the Piper turbocharged PA 31 "Navajo" series, in the "pilot operating handbook", which I don't have handy, but each engine's temp limits were established by the airframe manufacturer, as installed in their particular airframe. I'll look to see if I can find that number, I recall it is above that 220*F "ideal" number. As a service center, and piston engine overhaul repair station, I always told pilots to use 400*F cylinder head temp, and 200*F oil temp, as high limit goals for longest engine life expectations. The turbo'd models ran closer to about 435*F even in cruise. BTW, Lycoming, and Continental, take their oil temps at different locations, after, and before the cooler, which accounts for most pilots assumptions that the Lycomings run cooler... non aviators recall that light aircraft air cooled engines have pilot controlled fuel/air mixture controls in the cockpit, and the knowledgeable use of that one control has the greatest effect on full engine life... typically aided by an exhaust gas temperature gauge (there you go, Vic),
Mike
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Brian R Adams
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Re: Oil Cooler

#14 Post by Brian R Adams »

Mike,

Good info. In my post I was only addressing the topic of purging off volatiles, and how warm the oil needs to be for that. Lycoming (for their reciprocating engines) states in their manuals "Engine oil temperature should not be below 140°F (60°C) during continuous operation." And as I quoted previously the minimum value called out is 165°F for "continuous cruise." That could be many hours on end, so I assume it is calculated to keep the oil free of contaminants including H2O.

I did some more searching and found a post on an AOPA forum where a chap said (in response to "How warm must oil be to purge off volatile contaminants?") that Lycoming recommends 180°F for 30 minutes. However, I have yet to find that referenced in any Lycoming publication online. But it reinforces my personal goal of 185°F (sump temperature) for at least 20 minutes.

Brian
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Mike Horton
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Re: Oil Cooler

#15 Post by Mike Horton »

Brian, that is the very reason most light aircraft are delivered new with an oil cooler winterization kit. Some install directly over the oil cooler fins, others over the cowling air inlet, to restrict the in flight air flow. These are effective, and save the engine.
Mike
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