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Gentleman,

Just completed my condition inspections on mt Sonex OneX with a AeroVee engine. Did several test flights and noted the oil temperature went to 230 to 235 degrees in various flight condition. The oil temperature normally is less than 220 degrees.

The following are the steps I took to remedy the problem:
1. Checked and reset the secondary ignition.
2. Verified the Aeroinjector carburetor was properly tuned and adjusted.
3. Checked oil cooler to make sure it was clear and properly vented.
4. Cylinder compression was #1 105 psi, #2 120 psi, #3 125 psi, #4 120 psi.
5. Performed a leak down test. Was unable to register much differential pressure. I heard air escaping from the exhaust. Suspect head may need to be rebuilt. Could this be the cause of the high oil temperatures? Engine has 175 hours on it.

Looking for suggestion,

CPT. Tidy

Your oil isn't too hot, it's too cold. If your temp gauge is indeed accurate, you might consider adding an electric heater to the oil sump. Blocking off part of the cooler might work too.

Cpt.tidy wrote:Gentleman,

Just completed my condition inspections on mt Sonex OneX with a AeroVee engine. Did several test flights and noted the oil temperature went to 130 to 135 degrees in various flight condition. The oil temperature normally is less than 120 degrees.

CPT. Tidy

The minimum "Normal Operating" Oil Temp is 160 Deg. F.

From the AeroVee 2.1 Manual:

Operating Limitations
(Subject to change without notice)
Idle RPM..........................................................800-900 RPM
Cruise RPM.............................................. 3200 +/- 200 RPM
Maximum RPM.................................................... 4,000 RPM
Oil Temp. - Min................... (80 degrees for take-off) 160o F
Oil Temp. - Max.......................................................... 240o F
Oil Pressure - Min....................... 10 PSI (hot oil, idle RPM)
Oil Pressure - Max....................................................100 PSI
Oil Pressure@ Cruise............................................. 40-50 PSI
CHT @ Cruise......................................................350o-375o F
CHT @ Climb (5 min. max.)....................................... 420o F
CHT Max..................................................................... 450o F
EGT Max.................................................................... 1400o F

The manual can be downloaded here: http://www.aeroconversions.com/products/aerovee/index.html

It is usually pretty easy to check your oil temp circuit for accuracy with an ice bath and some boiling water. Should read about 32 Deg. F and 212 Deg. F.

Best of Luck,

Wes

Cpt.tidy wrote:Gentleman,

Just completed my condition inspections on mt Sonex OneX with a AeroVee engine. Did several test flights and noted the oil temperature went to 130 to 135 degrees in various flight condition. The oil temperature normally is less than 120 degrees.

5. Performed a leak down test. Was unable to register much differential pressure. I heard air escaping from the exhaust. Suspect head may need to be rebuilt.

Like others noted, all those temps are too cold. You don't have any issue with the oil temp being too high.

As for hearing air from the exhaust, as long as you get good numbers on your leak down test don't worry. On that note, a compression check is usually done with a differential compression test rig, at 80 psi. So you get a number in one gauge versus the number in the "constant" 80 psi gauge. So 80/80, or 72/80 or the like. If you get below 60/80 then you might do a little more investigation, but the 60/80 is not an instant issue. The psi numbers you gave don't have any meaning to most of us.

I'm sorry, but I've got to ask a stupid question.....are you reading Celsius or Fahrenheit? If you are in metric then it is definitely too high. I have a top mounted oil cooler on mine and initially no extra cooling, but I also had high oil temps and ended up cutting a small extra hole under the prop for air to blow over the oil pump and around the sump. For a 1" x 2" hole it made a big difference, it dropped 25 degrees Fahrenheit instantly. I wouldn't have thought that leaky valves would raise the oil temps much.
Good luck. Our summer time temps get bloody hot here.

There's that pesky metric system rearing it's ugly head again. Don't see that as a stupid question at all.

Sorry,

My fault. I made a typo. I meant 230 degrees, not 139 degrees.

Cpt. TIDY

Area 51% wrote:There's that pesky metric system rearing it's ugly head again. Don't see that as a stupid question at all.

Metric or English temperature scale was my question on reading that post. Only thing stupid though is the system the English stuck us with before they changed to metric.

David A.

DCASonex wrote:
Only thing stupid though is the system the English stuck us with before they changed to metric.

David A.

Here, here! With one caveat.

We haven't been under British rule for quite some time. I lay the blame on a primary education system unwilling to learn the "metric" or "SI" system so they can pass it on to the youth.

Wes

Hi all,

The Sonex plans show all measurements in English and metric units. Which did you pay attention to?

I only used the logical, easy units. Metric!