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01-17-2016, 09:27 AM
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Join Date: Apr 2015
Location: Omaha
Posts: 18
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Oil Cooler Bypass??
I have on-going issues with low oil temp in the colder months on my O-360 RV-6A. I tried the shutter method and tape but my temps are still 165 at best and it doesn't fit well since the oil cooler is a 9-row(I am not the builder). Could it be that the oil cooler is too large and keeps it too cool?. I am interested in installing a valve(butterfly valve) inline so that I can control the oil flow into the oil cooler but all threads relating to the subject are several years old and lead to dead ends.
Seems like the companies/suppliers have changed hands or gone out of business. Does anyone have a current option?
Thanks!
Chris
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01-17-2016, 09:57 AM
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Join Date: Dec 2007
Location: Fredericksburg, TX
Posts: 662
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At such a low oil temperature your vernatherm should be bypassing the cooler already.
__________________
Jim Averett
RV-8
TS36 - Silver Wings
Fredericksburg, TX
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01-17-2016, 10:31 AM
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Join Date: Dec 2006
Location: Belleville
Posts: 306
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49clipper
I have the same problem. Save yourself the time of a bypass, it most likely will not work. I took my oil out cooler of the circuit by putting a connector between the supply line and return line and it made no difference at all. The problem is too much cooling air from the inlets (IMHO). I have a 320-D1A. My engine runs 175 in the summer (even 90 degree days) and 145-150 in the winter. Completely bypassing the cooler did not even raise it one degree. Oh, and I have a blockoff plate completely covering the air blast tube to the cooler.
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01-17-2016, 10:35 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by flyinga
At such a low oil temperature your vernatherm should be bypassing the cooler already.
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Well, yes and no. When cold, the vernatherm is retracted. That opens a passage which allows partial bypass of the oil cooler, while some oil flow continues to go through the cooler.
This design scheme was intended to prevent non-flowing oil from congealing in the cooler when OAT is very low.
The common approach to raising oil temperature is to block airflow to the cooler. Some have found it advantageous to cover both the air inlet side and the air outlet side.
The other approach is to remove the vernatherm, install a viscosity valve assembly (a plunger and a spring), and add a ball valve in one of the cooler oil lines. This allows complete blockage of oil flow to the cooler...but be aware of the previously mentioned congealing oil problem.
Standard system schematic:
The so called "viscosity valve":

__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 05-06-2016 at 09:11 AM.
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01-18-2016, 03:56 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Every winter this subject comes up in the experimental world with the same misconceptions.
The vernatherm never blocks oil flow to the cooler, it only blocks flow back through engine if it is hot outside.
Winter ops and oil temperature has always been of concerned but not overwhelming so. Piper simply has a plate installed over cooler when temps are below 30 and go fly.
Yes, 180 OT is desirable but it is not mandatory, if it were the cooling system would have been designed to make it so. It is not so, so we go fly with low oil temp.
I have system that blocks 100% air flow across cooler and still do not see 180 except on warm day. On cold day it might get up to 140. It is not a big deal IMHO.
PS in addition to sump heater, I have a small heater on cooler. It facilitates oil flow through cooler on cold days which probably is good idea.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
Last edited by David-aviator : 01-18-2016 at 03:58 AM.
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01-18-2016, 05:41 AM
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Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,687
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Something else to look at, I've seen the Van's oil temp gauge read 20 deg low before.
__________________
Walt Aronow, DFW, TX (52F)
EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
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01-18-2016, 06:02 AM
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Join Date: Apr 2015
Location: Omaha
Posts: 18
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I have a dynon skyview with the EMS. I did not check the temp sensor but it is similar reading to the old sensor. I will check that for sure. I did notice a significant change when I installed the shutter. Before it was installed I could not hit 160 even in the fall when temps at 8000 ft were 35.
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01-18-2016, 06:08 AM
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Join Date: Apr 2015
Location: Omaha
Posts: 18
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Quote:
Originally Posted by David-aviator
Every winter this subject comes up in the experimental world with the same misconceptions.
The vernatherm never blocks oil flow to the cooler, it only blocks flow back through engine if it is hot outside.
Winter ops and oil temperature has always been of concerned but not overwhelming so. Piper simply has a plate installed over cooler when temps are below 30 and go fly.
Yes, 180 OT is desirable but it is not mandatory, if it were the cooling system would have been designed to make it so. It is not so, so we go fly with low oil temp.
I have system that blocks 100% air flow across cooler and still do not see 180 except on warm day. On cold day it might get up to 140. It is not a big deal IMHO.
PS in addition to sump heater, I have a small heater on cooler. It facilitates oil flow through cooler on cold days which probably is good idea.
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So maybe 160 is OK and the shutter is good enough? Thanks!
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01-18-2016, 06:19 AM
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Join Date: Nov 2008
Location: Shreveport, LA
Posts: 1,002
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Lycoming Operators Manual Says:
Ambient Temp Above 60*F then Desired Oil Temp 180
Ambient Temp 30 to 90 then Desired Oil Temp 180
Ambient Temp 0*-70* then Desired Oil Temp 170
Ambient Temp Below 10* then Desired Oil Temp 160
Omaha temp is showing 0*F this morning, so if I was seeing 165*, I would be ok with it. (sorry, I cant get the numbers to spread out like I want them, but you get the idea)
Last edited by blueflyer : 01-18-2016 at 07:44 AM.
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01-26-2016, 05:32 PM
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Join Date: Dec 2008
Location: Mckinleyvill, CA
Posts: 33
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Low oil temp
I'm having the same low oil temp issue with my IO-320-D1A in my RV-9A. I live out on the west coast with reasonably mild temps. Yesterday I launched into the touch and go pattern and the highest oil temp achieved was 161 deg F. The ambient was 58 deg F. My Lycoming manual states 180 deg F is minimum acceptable. I'm told that 180 deg is desired to evaporate any moisture/condensation that may accumulate in the oil and to provide maximum lubrication to all engine components.
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