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Ball Valve to control Oil Cooler FLow

edclee

Well Known Member
Patron
UPDATE-SUCCESS Ball Valve to control Oil Cooler FLow

Has anyone attempted installing a ball valve in one of the oil cooler lines to deal with too cool oil temps? I am concerned that completely blocking oil flow to the cooler may create oil flow to the engine. I know the vernatherm should act as a pressure bypass even if the oil temp is high enough to cut off the vernatherm blocking the bypass port but I does seem it would restrict oil pump output.
Ed
 
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Nope

Hi Ed,
The general approach to oil temp control is in the air supply. Much safer than oil restriction....simpler too. Lotsa information on here regarding oil cooler control.

Best,
 
I flew with Larry Vetterman in his Super Cub a few years back, and he’s got a knob to a ball valve to control flow to the cooler. No vernatherm installed. He says this is pretty common in the back country Cub world, and it sure seemed to work well for him!

Paul
 
Oil Cooler Valve

It is not possible to compromise oil pressure by closing the ball valve. Basically with the valve closed the engine reverts back to the same configuration as a non oil cooler engine, one example being early 0 235 engines installations as in some Pipers.
 
The valve is in the oil cooler line. The vernatherm is disassembled, with the guts taken out, and the housing tightened back in to plug that hole. The oil cooler bypass spring and plunger are put in the accessory housing (Lycoming parts 69436 and 62415). It is this spring/plunger which would then "ride" open if you closed the oil cooler flow completely. One should probably not allow the valve to completely close. I got this info from Larry V directly.

Most of our engines simply have a plug in this hole, which is just forward of the oil filter housing, on top.
 
A couple friends run with a bypass valve in the cooler lines. In cold weather operation, the oil normally on its way to the cooler is diverted back into the circuit . No need to remove or modify the Vernatherm
 
Modify the ball valve

I am not being a proponent of this solution but could not resist this recommendation. A hole can be drilled into the ball of the ball valve so that when it is in the closed position, a minimum amount of oil would still flow through the valve.

Sizing of the hole would be calculated based on the viscosity of the oil at temperature, pressure of the oil system, and the diameter of the ball.
 
Ball valve

Let me chime in here as I have this unit in my airplanes. I didn’t invent it but in 1984 my first -4 ran way too cool. A fellow and very knowledgeable RV recommended this to get the oil temperature up to a reasonable number. I was skeptical but took his advise and never looked back. It is important to set the valve up so full off still allows a small amount of oil to flow thru the cooler. No we never drilled any hole in the valve.
I was at Oshkosh and was approached by a guy explaining he had a problem with the oil temperature running too hot. I explained exactly how to do it and he called me with the results. Deleting the vernatherm and installing the spring and plunger reduced his oil temperature 35-40 degrees.
All of my years building exhaust systems I would get calls about high oil temps and if the builder was a hands on type I would explain how and why it works. I was asked many times to go public and post it, but I never did as I figured some guy would forget to watch the temperature and let it get too hot and blame me for it.
RVs aren’t the only place this is a common practice. The PA-18 150 supercub came out with the spring and plunger along with the oil screen and there was a plate that went on the nose bowl over the oil cooler entrance when the temperature was below 40F. The addition of the vernatherm and oil filter setup excluded the spring and plunger. Now there are different brands of oil filter setups and some use the same hole in the accessory case as the spring and plunger and some don’t.
Bottom line is the ball valve setup has been around for many years and thousands of hours of engine time and it works. The key is to watch and adjust the valve just like RPM and MP.
 
Problem Solved!!

... Go to our website and see our oil cooler shutters that are opened and closed
via a cockpit control cable. Thanks, Allan..:D
 
Ball valve

Oil cooler shutters work to warm up the oil via airflow control. The other part of the equation is oil temperature too hot. There have been many posts on this site regarding it. Testing has shown that a vernatherm is only 70% efficient, whereas the spring and Plunger without a valve inline sends oil to the cooler 100% of the time. So problem solved???
 
The only caution (other than a closed valve and getting too hot) is a closed valve at very cold ambients. I know the Continental design once full blocked oil from flowing through their cooler, but oil could cold enough to congeal in there and trying to establish flow would not work. A lawsuit changed the design to one with some non-zero minimum oil flow.

If any RV-er is flying lower than -20F then there are a lot of challenges in addition.

While we are wishing, I want a shutter with less restriction when open than the Vans style. Yes, Larry, hot oil. Something like snap shutters on trucks before ATAAC.
 
Ball valve

I have pondered oil congealing in cold wx and when I asked an oil engineer about the newer multi-vis oils vs the original straight grades I never got a straight answer. In all my years of aviation involvement I’ve never heard of or know anyone that has experienced their oil congealing. Most guys up north here use multi-vis oil.
If there is someone out there that has an answer to multi-vis oil congealing propensity, please give us some facts.
 
I have pondered oil congealing in cold wx and when I asked an oil engineer about the newer multi-vis oils vs the original straight grades I never got a straight answer. In all my years of aviation involvement I’ve never heard of or know anyone that has experienced their oil congealing. Most guys up north here use multi-vis oil.
If there is someone out there that has an answer to multi-vis oil congealing propensity, please give us some facts.

Oil congealing is a real possibility. I had it happen twice that both led to precautionary shutdown of one engine in a twin. Airplane came out of a heated hangar. Took off with oil temps in the green. When it was time for the vernatherm to open no flow through the cooler. The fix was to tape the bottom half of the oil cooler with muffler tape. Was using Phillips 20W50.
 
The valve is in the oil cooler line. The vernatherm is disassembled, with the guts taken out, and the housing tightened back in to plug that hole. The oil cooler bypass spring and plunger are put in the accessory housing (Lycoming parts 69436 and 62415). It is this spring/plunger which would then "ride" open if you closed the oil cooler flow completely. One should probably not allow the valve to completely close. I got this info from Larry V directly.

Most of our engines simply have a plug in this hole, which is just forward of the oil filter housing, on top.

To get cooler oil temps, I tried the 'Vetterman solution' many years ago. Bought the spring and plunger (with Superior part numbers), but they would not fit in my ECI engine. This surprised me at the time that my clone engine was not 'original Lycoming' in this regard.
 
Oil congealing is a real possibility. I had it happen twice that both led to precautionary shutdown of one engine in a twin. Airplane came out of a heated hangar. Took off with oil temps in the green. When it was time for the vernatherm to open no flow through the cooler. The fix was to tape the bottom half of the oil cooler with muffler tape. Was using Phillips 20W50.

Interesting. Didn't say what brand/model of engine, but Lycoming powered RV's have an open vernatherm bypass when cold.

In theory, cold oil flow is through both the cooler and the open bypass. When bypass oil temperature rises, the vernatherm extends, eventually blocking the bypass hole and forcing more flow* to the cooler path.

The "oil cooler always has flow, cold or hot" scheme is specifically intended to prevent congealing. The above incident seems to suggest that the cooler path congealed after liftoff, despite some flow. So was this a Lycoming, and what was the oil type and OAT? Do you happen to know which cooler?

The shutdown brings up another design point. If somehow the cooler path were to become blocked, the vernatherm itself has a spring loaded tip, see below. The arithmetic says it should come off the seat at 60~80 psi. As I understand it, the engine should not lose oil pressure even with a fully closed vernatherm and a blocked cooler. Remember, the system has a positive displacement pump.

*
Testing has shown that a vernatherm is only 70% efficient, whereas the spring and Plunger without a valve inline sends oil to the cooler 100% of the time.

Larry, could you tell us more about the tests resulting in the 70% figure? When you say efficient, do you mean it is leaking oil flow past the seated cone, and was that test performed with an 8432 dual pass cooler?
.
 

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I built a oil cooler-sized aluminum box on the front side of the cooler with a gate that controls air flow to the cooler. When the engine is cold (starting), the gate is closed (no air flow). As the engine warms up, the gate is opened by a cable control in the cockpit. It's on my pre-takeoff check list. Has worked very well for many hours.....
 
Got thinking about the vernatherm's spring rate, and the interaction with the available oil coolers.

Above I wrote "the arithmetic says it should come off the seat at 60~80 psi". However, it's only true give a vernatherm which has extended 0.050" past initial seat contact, as seen in the blueprint. Closer to reality is to recognize the much smaller seat pressure in the range between initial seat contact and the specified 0.050" spring compression.

The spec says 15 to 20 lbs at 0.050" so the spring rate is 300 to 400 lbs per inch. So, at initial contact, spring pressure is zero, and any pressure delta between the accessory case supply port and the oil cooler return port will push the cone up off the seat...the vernatherm bypass will leak. Oil temp does not drop much, so the vernatherm's wax capsule extends some additional length, further compressing the spring.

Given the 15~20 lb spec and port area of 0.250', the spring force and delta psi to push the cone off the seat would be as below for each extension past initial contact:

ext F psi F psi

0.010 3lb 12 4 16
0.020 6 24 8 32
0.030 9 36 12 48
0.040 12 48 16 64
0.050 15 60 20 80

Now look at the pressure drop across an 8432 dual pass cooler. That drop plus any viscous friction in the cooler lines and fittings creates the pressure delta across the vernatherm bypass port. We flow about 7 gallons per minute, or a bit over 52.5 lbs of oil, so the chart pressure drop for the cooler is about 15 psi at 235F oil temperature. It will be a lot more at some lower temperature, as the oil will be more viscous.

Larry mentioned 70% efficiency, and I hope to hear more. Assuming efficiency measures leakage, I think he is dead right. The numbers suggest that given an 8432 and a desired oil temperature below 200F, the vernatherm must extend as much as 0.030" past seat contact if it is expected to not leak, i.e. the cone not be pushed off the seat. The exact value is unknown, but for sure, it is well beyond just seat contact....and oil cooler choice has a profound effect.
 
Interesting. Didn't say what brand/model of engine, but Lycoming powered RV's have an open vernatherm bypass when cold.

.

Sorry it was Piper Aerostar 601P/700 with Lycoming 350 HP TIO-540-U2A engines. The issue was not unique to this particular model.
 

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Sorry it was Piper Aerostar 601P/700 with Lycoming 350 HP TIO-540-U2A engines. The issue was not unique to this particular model.

Thanks Glenn.

That engine uses the same vernatherm as my 390. The cooler is a big bar and plate single pass. Common Lycoming oil system. It would have had some cooler flow when it came out of the heated hangar, although as noted, not full volume, as the cooler bypass was open until oil temperature got to 180 or more. Call it equivalent to Larry's ball valve partially open.

How cold was the OAT? Do you know if the oil was 100W or multigrade? Lot of ramp and taxi time at 1000 RPM? That would cut flow to just over a third.
 
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Thanks Glenn.

That engine uses the same vernatherm as my 390. The cooler is a big bar and plate single pass. Common Lycoming oil system. It would have had some cooler flow when it came out of the heated hangar, although as noted, not full volume, as the cooler bypass was open until oil temperature got to 180 or more. Call it equivalent to Larry's ball valve partially open.

How cold was the OAT? Do you know if the oil was 100W or multigrade? Lot of ramp and taxi time at 1000 RPM? That would cut flow to just over a third.

Outside air was in -10C range on the ground. Oil was Phillips 20W50. It always took me 8 - 9 mins to get oil temp in the green before I did my run up. Left a 50F degree hangar and then approximately a 15 min fuelling before start.
 
I was at Oshkosh and was approached by a guy explaining he had a problem with the oil temperature running too hot. I explained exactly how to do it and he called me with the results. Deleting the vernatherm and installing the spring and plunger reduced his oil temperature 35-40 degrees.

If you have a stock Lycoming oil filter adapter you can install the bypass spring and plunger for summer operation without removing the Vernatherm. This causes all the oil to flow through the cooler and negates the effect of the Vernatherm. My oil temps drop about 15-20F when I do this. This won't work with most aftermarket oil filter adapters because the plunger and the Vernatherm would interfere with each other in the housing, but you can still remove the Vernatherm and install the bypass plunger.
There are many factors that can cause high oil temp (use the search function and you'll get many hits), and efforts should be made to correct those problems first. If you've tried everything and your oil temps are only a little higher than you'd like, this trick might help you.
 
Outside air was in -10C range on the ground. Oil was Phillips 20W50. It always took me 8 - 9 mins to get oil temp in the green before I did my run up. Left a 50F degree hangar and then approximately a 15 min fuelling before start.


Well that's not crazy cold. So what actually happened that made you shut it down? Your first post only says "When it was time for the vernatherm to open no flow through the cooler." What was the cockpit indication? Oil temperature went into the red, or you had no oil pressure indication, or ?
 
Well that's not crazy cold. So what actually happened that made you shut it down? Your first post only says "When it was time for the vernatherm to open no flow through the cooler." What was the cockpit indication? Oil temperature went into the red, or you had no oil pressure indication, or ?

Oil temperature went into the red. Oil pressure was slowly dropping but shut down before it got to low. Both times landed and waited for a while then proceeded with the trip. All was Ok. I think sitting with the hot soaked engine allowed what ever was congealed or frozen to defrost. As mentioned previously this happened to others with similar makes. Perhaps it is unique to this model. After two incidents I just automatically covered the oil cooler. It is surprising how small of an area you need to have open on the cooler in colder weather. Once I covered the cooler up partially I left it for the entire winter.
 
Has anyone attempted installing a ball valve in one of the oil cooler lines to deal with too cool oil temps? I am concerned that completely blocking oil flow to the cooler may create oil flow to the engine. I know the vernatherm should act as a pressure bypass even if the oil temp is high enough to cut off the vernatherm blocking the bypass port but I does seem it would restrict oil pump output.
Ed

Yes. Installed the anti spat air control device. Worked exactly as advertised, and I didn't have to alter the oil system. This is a no brainer to me. Why make this so complicated, performing "heart bypass surgery" when you could "alter your diet??"

In addition to increasing the oil temperature during cruise, it also allows me to climb longer in hot weather. In a climb, the oil is relatively slow to warm versus the cylinders. I close off the air on climb, and since installed 10-months or so ago, I can make it significantly easier to target altitudes without reducing power or stair stepping for CHT control. Just have to remember to open the shutter, but the EMS will remind you otherwise. My oil cooler is mounted behind the number 4 cylinder baffling.
 
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Oil temperature went into the red. Oil pressure was slowly dropping but shut down before it got to low. Both times landed and waited for a while then proceeded with the trip. All was Ok. I think sitting with the hot soaked engine allowed what ever was congealed or frozen to defrost. As mentioned previously this happened to others with similar makes. Perhaps it is unique to this model. After two incidents I just automatically covered the oil cooler. It is surprising how small of an area you need to have open on the cooler in colder weather. Once I covered the cooler up partially I left it for the entire winter.

That's great info Glenn. Clearly the cooler stopped flowing after the chill down time for fueling, then some taxi and initial flight time, when the open vernatherm bypass makes flow through the cooler quite low.

The obvious difference between the Aerostar installation and our typical RV is the cooler location. The Aerostar has it right out there in its own nosebowl inlet, receiving the full force of available dynamic pressure. The typical RV receives air already warmed by ram heating and the upper fins, at less pressure, i.e. less mass flow. The Aerostar install would also have long oil lines from the back of the engine to the front of the nacelle, with flow loss to viscous friction. The result would be a colder cooler with little flow during the vernatherm open period.

I'm going to ask Phillips for a viscosity vs temperature chart, as I would not have guessed the multigrade as being likely to congeal. Hey, where I live, 40F is cold.

Your oil pressure loss is interesting. I would expect some pressure loss to push the vernatherm cone off its seat. As the oil got warmer, the wax capsule would extend further, compressing the spring and perhaps increasing the loss. How low did it go? Still in the green, but low enough to shut it down as a precaution, maybe saving some very large engine bucks? Or was it deep in the red?
 
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Oil cooler air flow gate

Found a picture of the airflow control box for the oil cooler. Fashioned of aluminum welded by my neighbor. The cooler is mounted to the engine mount with a steel mount that doesn't show in this photograph. The air is taken off the baffling plate and controlled by a gate on the back side of the cooler operated from a control in the cockpit. Works well. In the Winter (cold weather) I have the oil pre-heated with an oil warming plate mounted to the bottom of the oil sump. Starting: oil cooler air flow gate stays closed until oil temperature starts to come up to green arch temperature, then opened. RV-4s seem to run cool and I have never had either engine cooling or oil temperature problems even in the hottest or coldest weather. Good baffling is key..........:)
 

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That's great info Glenn. Clearly the cooler stopped flowing after the chill down time for fueling, then some taxi and initial flight time, when the open vernatherm bypass makes flow through the cooler quite low.

The obvious difference between the Aerostar installation and our typical RV is the cooler location. The Aerostar has it right out there in its own nosebowl inlet, receiving the full force of available dynamic pressure. The typical RV receives air already warmed by ram heating and the upper fins, at less pressure, i.e. less mass flow. The Aerostar install would also have long oil lines from the back of the engine to the front of the nacelle, with flow loss to viscous friction. The result would be a colder cooler with little flow during the vernatherm open period.

I'm going to ask Phillips for a viscosity vs temperature chart, as I would not have guessed the multigrade as being likely to congeal. Hey, where I live, 40F is cold.

Your oil pressure loss is interesting. I would expect some pressure loss to push the vernatherm cone off its seat. As the oil got warmer, the wax capsule would extend further, compressing the spring and perhaps increasing the loss. How low did it go? Still in the green, but low enough to shut it down as a precaution, maybe saving some very large engine bucks? Or was it deep in the red?

Thanks for your explanation. I think your reasoning is right on.
The oil pressure was never near the red. I shut it down as the oil temp when into the red. I figured that the oil temp being in the red and confirmation that it was not the gauge with the lower oil pressure. I shut it down to save the engine. Both flights were early morning before daylight but good VFR conditions.
 
Yes. Installed the anti spat air control device. Worked exactly as advertised, and I didn't have to alter the oil system. This is a no brainer to me. Why make this so complicated, performing "heart bypass surgery" when you could "alter your diet??"...

Actually, the addition of the Vernatherm is the "alteration" of the oil system as designed. Reverting back to the viscosity valve has proven by many to be a more effective means of delivering the full volume of oil to the cooler than the admitedly problematic Vernatherm. The Vernatherm modification is a "pilot convenience device" which theoretically makes oil temp control "automatic". For many, it works pretty good. For some edge cases (like me), the added percentage of oil the "outdated" viscosity valve throws at the cooler is worth the added complication of manual control. And has been illustrated by many here, restricting oil flow with a ball valve does not hurt oil flow to the bearings - thats EXACTLY what the viscosity valve is designed to prevent.

So in summary, evidence suggests the Vernatherm moves less oil to the cooler than the viscosity valve, and adding a shutter to control airflow adds additional efficiency losses even when wide open. Given the two strikes there, a simple ball valve instead makes a compelling case for superior cooling and reduced mechanical complexity.
 
The oil pressure was never near the red. I shut it down as the oil temp when into the red. I figured that the oil temp being in the red and confirmation that it was not the gauge with the lower oil pressure.

Very useful information, thanks.

I think some of my previous reasoning was incorrect, specifically regarding pressure drop across the vernatherm tip. Reconsidering, I think the pressure drop across the vernatherm port (with the cooler blocked) is simply the difference between pump outlet pressure and the sum of main gallery pressure plus filter drop. Your (apparently moderate) loss of oil pressure was probably just a function of reduced viscosity as the oil temp neared redline.

Anyway, the story seems to suggest the spring loaded tip on the vernatherm works as expected. Given a cooler blockage, the vernatherm cone is forced off its seat so oil supply is not lost. With a positive displacement pump it doesn't have a choice. It's no different from the no-vernatherm system with a viscosity valve (the 69436 and 62415 spring and plunger). It is the plunger which gets pushed upward to open the bypass when the ball valve is closed, or the cooler is blocked.
 
Success!

Well, I installed the ball valve yesterday and flew the plane this morning. OATs in the 30s. Previously with no modifications the best I could do is get the oil temp to the 130s in this temp. With the oil cooler completely blocked on the inlet side with tape, I could get it to the 150s at this temp and now with the ball valve closed I can finally get to the 180s. Even in the summer the highest temperature I can manage at 85-90 OAT is 175-180 so I think this well work out. I have verified the oil temp sender is correct, using the boiling water test, so I am a happy camper. Now I need to sort out how I am going to control the valve through a 90 degree handle movement.
Ed
 
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45 degrees on either side of neutral works fine for a linear actuation like a cable. Same as the throttle butterfly.
 
Installed the viscosity valve (no ball valve yet) and did a good hot weather workout in formation with another Rocket today. Despite me having cooling jets for the pistons (big heat load on the oil) and him not, I was consistently 15 degrees cooler than him in all phases of flight. I never saw over 204 which is unusual for me even in the winter. Big, big improvement in oil cooling for 15 minutes of work.
 
Oil Cooler Ball Valve

Where did you install the ball valve? How did you mount it?

-Jason

This is how I installed mine. Several hundred hours of operation now and no issues at all. Even in the coldest WX at 15000 feet I can keep the oil temp at 180 degrees with zero additional heating of the oil here in SC at 100 degree August days. I control it from the panel with a simple push pull cable to an arm on the ball valve. It is mounted directly on the oil cooler inlet port. I purchased the valve from Amazon. "Denord Stainless Steel Mini Ball Valve, 3/8 NPT Male, 3/8 NPT Female". I removed the little thumb handle and fabricated an aluminum arm to control the valve. See pics for details.
Ed
 

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Angle

Thanks, Ed. What is the purpose of the small piece of angle aluminum on the top?

-Jason

The aluminum angle is a stop for the actuator arm. The original thumb turner had a stop built into it so you could go from fully open to fully closed, once that was removed the fabricated arm needed a stop. If you can visualize the control arm being pulled back by the cable, you can see it will fetch up on the angle. If you need I can take a pic with the cable fully retracted so you can see the stop in effect.
Ed
 
If you can visualize the control arm being pulled back by the cable, you can see it will fetch up on the angle. If you need I can take a pic with the cable fully retracted so you can see the stop in effect.
Ed

Thanks, that explains it. No photo needed!
 
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