Wayne

Wayne

Well Known Member
I have exhausted all my ideas and the mechanics ideas on how to reduce the oil temperatures on my -7a

Here's the facts
-IO-360A3B6D 200hp 850 SMOH out of Mooney and has been run 6 hours on test stand with clean bill of health
-Van's FWF kit including oil cooler
-Oil Cooler mounted as per plans at rear baffle (pilot side)
-Temperatures running upto 255F
-Oil Pressure at 65#
-Running 6.5 gallons of break in oil (mechanic said that reg oil will help upto 5 deg F cooler

I have done the following:
-replaced and calibrated oil temp sender and guage
-replaced vernatherm
-Changed hoses to and from oil cooler
-enlarged out flow by cutting 1.5 inches off bottom cowl outlet
-installed louvers at cowl outlet

all the above seen no changes in temps

My mechanic and I are scratching our heads and looking for the solution(s).

Appreciate your help

Wayne
C-GOYA 7 eh?
2.5 hours and grounded
 
Oil Temp

Wayne,

Check the vernatherme that you removed. Look for a ring around the conical portion of the valve. Does the ring go all the way around the circumference of the valve?? If it does not then the seat in the case may not be symetrical and needs to be "lapped". There is a special tool to "grind" the seat to make a seal with the vernatherme. If it does not seat then oil is bypassing the oil cooler and being reintroduced into the engine w/o cooling.
I went thru this excercise with a Mooney 201 (same engine as yours) and after the correction my temps went down about 20-30 degrees.

What type of oil cooler do you have---the true Stewart Warner is about 15-20% more efficient than the unit Vans sells in his FF kit. The down side is that it costs about 150-200 more.

Hope this helps.

Cheers,

db
RV9a---Flying
 
oil temp

I had a similar problem but not quite as high with a IO360-A1B6. Played all the games and tried all the suggestions. Finally bought a Stewart Warner 9 row cooler and oil temps are around 195.

SO, my only suggestion would be buy the SW now and get it over with :)


Doug
7A flying 2 years
 
Oil temps

I've read that the angle-valve engines put more heat into the oil, becuse they use oil-splash to cool the piston skirts (I haven't independently verified it, but fond it reasonable).

When I built my airplane, I talked with Pacific Oil Coolers and bought a large Stewart-Warner cooler that is usually recommended for the IO-540. It is mounted on the right firewall with a 4-inch SCAT tube and firberglass plenum.

I live in Memphis, and have flown in temps as high as 105 F without seeing oil temps above 227, even in the climb. Winter or summer (25 to 105 OAT) my cruise oil temps stay in a range from 175 to 190. I haven't found cold weather shutters necessary, but rarely fly in temps below freezing, and never (yet) below 25.

I have read several reports of high oil temps that were solved by going to the bigger S/W cooler, and when Greg Hale posted his saga just before I bought my cooler, I just copied his setup and have essentially identical results.

The big cooler was expensive, but on the other hand I only bought one ;-)

HTH

James Freeman
RV-8 IO-369 C1D6, cool oil temps
 
flyeyes said:
I have read several reports of high oil temps that were solved by going to the bigger S/W cooler, and when Greg Hale posted his saga just before I bought my cooler, I just copied his setup and have essentially identical results.

The big cooler was expensive, but on the other hand I only bought one ;-)

HTH

James Freeman
RV-8 IO-369 C1D6, cool oil temps
Click to expand...

That was my thought as well so I deleted the standard Van's oil cooler from the FWF kit I'm ordering this coming week and sending off to Pacific to get the Stewart Warner and install it from the get-go.

Related to the original question; I've never heard of an instance where changing out to the SW cooler did NOT make a noticeable difference in temps.
Sounds like a no-brainer.
 
Stewart Warner 9 row on 200hp Lyc

I'm hijacking this old thread since its closely related to a question I have about a Stewart Warner 9 row oil cooler that came with my 200 hp IO-360 A1B6 engine that came off a Beech C24R Sierra. Can anybody tell me whether this cooler (Stewart Warner Model 8432K) should work well with this stock engine in a 7A? :confused:

Seems like it should, but just wondering (before I overhaul the cooler) which S-W people are using in place of the Vans cooler which is reported not to work too well with the angle-valve engine.
 
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1. Get the SW cooler 8406R. Do not get a knock off. The $ 471.00 one here: http://www.aircraftspruce.com/catalog/eppages/stewarnercooler.php

2. Why are you running break in oil if the engine has 850 hrs? 6.5 Gal? You mean qts? Fill it up to 8. If it doesn't spit the extra out the breather the extra 1.5 qts reduces the oil temp because the heat load is absorbed and handled by a larger mass.

3. Scrutinize your baffling and the area around the cooler for air leaks, often the bottom and top of the opening from the rear baffle has a quarter inch gap that lets air leak out without going through the cooler. Be very skeptical of any leaks to create as much high pressure as possible on the top side.

4. Crank the oil pressure up to 85 psi hot at 2700 rpm.

5. Don't fly slow. Climb out at higher IAS. What OAT and IAS are you flying around at getting the 255?
 
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high oil temps

I lowered my oil temps 20 deg by closing off one end of each inlet ramp of the top cowl. A lot of air escapes thru and into the lower cowl. If yours are open, try closing each side with foam or anything temporarily and see if it helps. :)
 
asav8tor said:
1. Get the SW cooler 8406R. Do not get a knock off. The $ 471.00 one here: http://www.aircraftspruce.com/catalog/eppages/stewarnercooler.php

2. Why are you running break in oil if the engine has 850 hrs? 6.5 Gal? You mean qts? Fill it up to 8. If it doesn't spit the extra out the breather the extra 1.5 qts reduces the oil temp because the heat load is absorbed and handled by a larger mass.

3. Scrutinize your baffling and the area around the cooler for air leaks, often the bottom and top of the opening from the rear baffle has a quarter inch gap that lets air leak out without going through the cooler. Be very skeptical of any leaks to create as much high pressure as possible on the top side.

4. Crank the oil pressure up to 85 psi hot at 2700 rpm.

5. Don't fly slow. Climb out at higher IAS. What OAT and IAS are you flying around at getting the 255?
Click to expand...

I completely agree with 1, 3, and 5 and have no opinion about #4. However, #2 - more oil won't hurt, but it won't help either. You're adding what, 2 or 3 pounds of oil to a system (engine, cooler, oil, etc) that weights 300+ pounds? That 1% difference in mass isn't going to matter in the big scheme of things.

In the end, what matters is whether your oil cooler can reject as much or more heat as the engine imparts to the oil. To balance that equation, you either find a way to reduce the engine's heat (better baffles, etc) or find a way to make the oil cooling system reject more heat - better cooler, better airflow through the cooler, etc.

One thing to verify is that your oil cooler hoses are oriented so oil flows through the oil cooler and there isn't a possibility of the cooler being filled with an air bubble. Ideally, the hose carrying oil to the cooler should enter at the bottom of the cooler and the "out" hose would be at the top. Depending on cooler orientation, it is OK to have both the in and out hoses entering the cooler at the top of the cooler. If both hoses (or the out hose) is at the bottom of the cooler, you might have an air bubble trapped in the cooler, more or less negating its effectiveness.
 
If it doesn't spit the extra out the breather the extra 1.5 qts reduces the oil temp because the heat load is absorbed and handled by a larger mass.
Click to expand...

I'm not an engineer, but I'm pretty sure that's not correct.

A larger mass of oil will lengthen the time it takes to reach a steady-state, but the temps will stabilize at the same point..

There might be a minor contribution from heat loss through the walls of the sump with a higher oil level, but I'd bet that it's insignificant.

More oil won't change airflow or oilflow through the cooler as long as the oil pickup is covered.

Am I missing something here?
 
The engine is pressure lubricated. The only thing the sump does is store the oil in a place for the suction screen to pick it up. You can run the engine on 2 qts. If you do you will see higher oil temps. Try it.
 
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asav8tor said:
The engine is pressure lubricated. The only thing the sump does is store the oil in a place for the suction screen to pick it up. You can run the engine on 2 qts. If you do you will see higher oil temps. Try it.
Click to expand...

Don't two of your statements disagree with each other? If all the sump does is serve as a reservoir for oil, how does having more oil in there aid cooling?
 
The mass (oil qty, not engine mass) that has to do the work, ie lubricate, transfer heat, etc is taxed less when there is more of it to go around. If the engine needs only 2 qts and you increase it by 400 percent to 8 qts the oil will run cooler. Go fly with 2 then go fly with 8. I'm not claiming this is a cure for oil cooler or baffle issues. Consider if the sump held 55 gallons but the engine only needed 2 qts. You think everything else being equal the oil temp would remain the same regardless 2 qts or 55 gal? 8 qts is 23% more than 6.5. I have observed this temperature relationship on the temp gauge by running between 4 and 8.
 
asav8tor said:
The mass (oil qty, not engine mass) that has to do the work, ie lubricate, transfer heat, etc is taxed less when there is more of it to go around. (snip) Consider if the sump held 55 gallons but the engine only needed 2 qts. You think everything else being equal the oil temp would remain the same regardless 2 qts or 55 gal? .
Click to expand...

That's exactly what I'm saying. I think if the sump held 55 gallons (and you ignore the heat loss through the walls of the much bigger sump required) then the engine might take several hours to reach a stable temp, but it would be the same temp.

The engine's waste heat will first heat the oil, then the hot oil will transfer the heat to the cooling airflow through the cooler, lines, filter, etc. The total mass of oil doesn't affect that transfer assuming there is enough for the oil pump to pick up and fill the lines. The output of the oil pump, surface available for cooling, and temperature and density of cooling air do.

A bigger sump will help, but only because it has surface area exposed to cooling air.

Think about a car's radiator where the liquid really only has one function: cooling.
We don't use "coolant sumps" in cars because they aren't helpful. There is only enough water/antifreeze to fill the radiators, lines, and cooling passages in the block. Any excess only adds weight and delays the engine reaching operating temperature.
 
flyeyes said:
That's exactly what I'm saying. I think if the sump held 55 gallons (and you ignore the heat loss through the walls of the much bigger sump required) then the engine might take several hours to reach a stable temp, but it would be the same temp.
Click to expand...


Go fly with 4 qts then add up to 8 and fly again.:cool:
 
Hummmmmm,

This might sound stupid, however I have a really, really good reason for asking.....

Is the temp sensor in the wrong hole....?

The vernatherm bypass hole is next to the oil temp sensor hole. The vernatherm hole is about 6" deep while the oil sender hole is about 2" deep.

The oil sensor hole is on the oil housing........

The things that make you say HUMMMMMMMMM..........
 
oil temps

Wayne,
I am considering installing the louvers. It sounds like they did not do the trick for you. Have you solved the high temps yet? What did you do?
 
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