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Oil Cooler Bypass??

T

TME2FLY

Member
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
 
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.
 
flyinga said:
At such a low oil temperature your vernatherm should be bypassing the cooler already.
Click to expand...

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":

 
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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.
 
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Something else to look at, I've seen the Van's oil temp gauge read 20 deg low before.
 
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.
 
David-aviator said:
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.
Click to expand...


So maybe 160 is OK and the shutter is good enough? Thanks!
 
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)
 
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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.
 
For whatever reason, the O-320 D1A and D2As don't dump much heat in the oil. A number of flyers with those engines, me included, have observed this. I have exactly the same issue with my IO-320 D2A in the winter months, even with the oil cooler fully blocked off. I flew in 24F OAT a few weeks ago and never saw the upside of 158F O.T. Less than 2 weeks later the OAT was up to 72 and I again flew (with the oil cooler stilled 100% blocked off) and my max OT was 191F.

A couple years ago, one of our local hangar curmudgeons observed, "For whatever reason, the O-360s seem to dump a lot more heat to the oil than the 320s." That does in fact seem to be the case. :)
 
Low Oil Temps

I've been working low oil temps for a year now, and my performance is like you guys ... RV-8 with IO-360 M1B. What I've learned to date:

1. Vernatherm works as advertised. Tested proper expansion on my stove using a candy thermometer.
2. Oil Temp gauge works as advertised.
3. Installed cockpit-controllable oil-cooler vent (fully blocked) only helps to increase oil temp in warmer weather or higher power settings.
3. Cruising around at 10K ft., at 45% power, LOP, economy cruise, 35 degrees OAT, I see 160 degrees if I'm lucky...more like 150 degrees at 30 degrees OAT.

My conclusion is I've done a good job sealing up the cowling leaks (good), but everything works so well that the stock Van's intake/exhaust is too large for the cooling job. As a point of reference, Sam James cowling reduces intake area by 40%.

I've moved onto experimenting w/ smaller intake/exhaust areas, and encourage others to do the same. Will share my results once my grass strip has a chance to dry out (this has been a very wet spring for us in central NY!).

First step is to reduce the intake area by 25%. I've done this using foam strips inside the intakes and can't wait to fly!
 
Rupester said:
For whatever reason, the O-320 D1A and D2As don't dump much heat in the oil. A number of flyers with those engines, me included, have observed this. I have exactly the same issue with my IO-320 D2A in the winter months, even with the oil cooler fully blocked off. I flew in 24F OAT a few weeks ago and never saw the upside of 158F O.T. Less than 2 weeks later the OAT was up to 72 and I again flew (with the oil cooler stilled 100% blocked off) and my max OT was 191F.

A couple years ago, one of our local hangar curmudgeons observed, "For whatever reason, the O-360s seem to dump a lot more heat to the oil than the 320s." That does in fact seem to be the case. :)
Click to expand...

this is same for me. I don't worry about the oil temp on my -9. Block the oil cooler in the Winter and open it in the Summer and just fly it.
 
No research at all, but - -

On ROTAX we can install a thermostat that works very well. Does not allow oil to go thru cooler until up to therm temp range. Uses 1/2" ID hose. Maybe that is an issue. Just noting.
 
Check your oil analyses ....

I used fret over low oil temps, but eventually decided to just watch my oil analyses carefully, since the lab always tests for water content. I've yet to have an oil report show any water at all. So - following the advice above - I block the cooler in winter, open it summer, and just "fly the plane." :)
 
Rupester said:
I used fret over low oil temps, but eventually decided to just watch my oil analyses carefully, since the lab always tests for water content. I've yet to have an oil report show any water at all. So - following the advice above - I block the cooler in winter, open it summer, and just "fly the plane." :)
Click to expand...

same here. I am not in the camp that believes running oil temps in the 140-160* range causes damage. It is really a matter of temp & run time, along with the oil's retained water volume. I have all confidence that limited water will evaporate at 140* on a 1.5 hour run. However, load up your oil with water by a bunch of successive short runs and you'll struggle to get the water out at lower temps. High temps as well. The lower the temp, the longer the run needs to be to get rid of water. However, an engine that doesn't see short runs does not create a significant build up of water that needs to be removed.

Larry
 
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