Oil temp question.

[Lood]

I have about 20 hours on my new engine now and today the oil temp had me rather worried. Right at the beginning, the oil temp ran just about at the top of the green arc, but as the breaking in of the engine progressed, the oil temp decreased. For about the last 10 - 12 hrs, it sat firm at around 180 - 200 deg. On the first 2 hr leg this morning, all was normal. When I took off again for a short 25 min hop to refuel, I noticed the oil temp right at the top of the green arc. OAT was around 10 deg celsius.
We landed, refueled and took off again for another 2 hr leg. I climbed at 120 mph to FL095 and the oil temp was just under redline all the way up. Once settled in the cruise with WOT (19"), 2450 rpm, 80 deg ROP, OAT 7 deg celsius, nothing changed. After about an hour, I went LOP and all other engine temp dropped substantially, but the oil temp stayed at about redline all the way to landing. Oil pressure was very good and all other temps were very cool though and I must add that my original oil temp guage is not very steady but fluctuates all the time. However, it certainly seems to be running a lot higher than it did.

Could this have something to do with the engine's break in? The first flight we did with the new engine was at sea level, at full power and for almost two hours. After that I flew it at higher altitudes, but for the first 14 hours, I always kept the power above 75% - WOT and alternating the rpm between 2500 - 2700.
Initially, oil consumption was just about nil and I added half a quart after about 7 - 8 hrs when the oil level on the dipstick fell below 7. After that, the oil consumption increased and is now more in the region of 1 quart every 5 hours. I haven't allowed the oil level to come down to 6 on the dipstick as all of my flights have been more than 2 hrs and I don't want the oil level to drop below 6 at this stage. So, maybe the engine is just blowing the oil out due to the high level, but why the increase in consumtion and now the higher temp?

 

[ELT]

NOTING THE SAME OIL TEMP ON MINE.  I am just breaking in the IO 360 in my E.  Rebarrelled steel cyl and everything replaced with new but the crank shaft.  I run it hard >25/25.  At 3 hours the CHTs dropped and I began flying with the cowl flaps closed.  At 12 hours did compression test 77/72/72/78 over 80, filter check, oil change and plug check.  1 quart oil used in 12 hours.  My oil temps run just below redline.  The next 7 hours used zero oil.  Did engine base line yesterday.  All very good max CHT 350 at 100% power.  The oil temp is 180-200.  I think it is high but the mineral oil is very thin.  I am still flying low, less than 6,000 to keep the power up.  I also suspect the accuracy of my oil temp gage.  I will be contacting the overhauler next week.

Eddie

[jetdriven]

Lood, check your vernatherm in boiling water, also, do you have chrome or cerminil cylinders?

[jnisley]

We're 34 hours into a top overhaul. The first 15 hours or so our oil temps were top of green and getting close to redline during climbouts. They are green to top of green now (170-200). I was suspicious about the accuracy of the gauge so I decided to install a oil temp probe for our EI engine analyzer. When I was researching this I discovered there was a probe installed and we never knew it. (imagine that, over 400 hours in the plane and didn’t know maybe if I look hard enough I might find a second engine)  When comparing the two, the factory gauge seems to be reading a little high. Very top of green is 200-205 on the digital gauge.

[Bill_Pyles]

I live in AZ and was struggling to keep the EI-reported oil temp below 200 deg F.  In fact, my normal in cruise at 10500, 21MP and 2400 RPM was 205-214 deg F.  My original analog oil temp gage always stays in the green or just to the right of green.  Even in the spring time, it is easy to see 65 degrees OAT at 9000 ft or more.

I recently made two changes: 

1)  changed the oil to Aeroshell W100 (from Phillips XC 20-50) and,

2) I lengthened the control rod on the left cowl flap such that the cowl flap is now open about 5/8" when in the closed position.  The left side is where the oil cooler lives.

Last week I flew to San Jose and the oil temp in cruise at 9500 was around 195, so I am happy about that.  I don't know if the reduced oil temp was due to the fresh oil or the cowl flap adjustment, but there you have my story.  By the way, the cylinders ran 325-390 and EGTs were in the low 1300s.  Burned 34 gallons for a 4 hr flight, so I thought that was pretty good too.

[jetdriven]

I believe the J oil temp is read after the oil cooler.  Other monitors may read before the oil cooler, which is going to be 20-40 degrees hotter.  What's the max "real" oil temp?   285 degrees?   Ins't the max instantaneous oil temperature (inside a main bearing, etc) about 20-40 degrees higher than the oil cooler inlet?   You folks with oil temp problems may not be problems at all.

[Cruiser]

+1 on sensor location. You need apples to apples comparison with the probe in the same spot at the OEM guage.

[jnisley]

On our M20F the OEM probe is up by the filter (see photo) and the EI probe is on the bottom of the oil sump.

[dmevans]

On 5/5/2012 at 8:20 AM, Lood said:

I have about 20 hours on my new engine now and today the oil temp had me rather worried. Right at the beginning, the oil temp ran just about at the top of the green arc, but as the breaking in of the engine progressed, the oil temp decreased. For about the last 10 - 12 hrs, it sat firm at around 180 - 200 deg. On the first 2 hr leg this morning, all was normal. When I took off again for a short 25 min hop to refuel, I noticed the oil temp right at the top of the green arc. OAT was around 10 deg celsius.
We landed, refueled and took off again for another 2 hr leg. I climbed at 120 mph to FL095 and the oil temp was just under redline all the way up. Once settled in the cruise with WOT (19"), 2450 rpm, 80 deg ROP, OAT 7 deg celsius, nothing changed. After about an hour, I went LOP and all other engine temp dropped substantially, but the oil temp stayed at about redline all the way to landing. Oil pressure was very good and all other temps were very cool though and I must add that my original oil temp guage is not very steady but fluctuates all the time. However, it certainly seems to be running a lot higher than it did.

 

Could this have something to do with the engine's break in? The first flight we did with the new engine was at sea level, at full power and for almost two hours. After that I flew it at higher altitudes, but for the first 14 hours, I always kept the power above 75% - WOT and alternating the rpm between 2500 - 2700.
Initially, oil consumption was just about nil and I added half a quart after about 7 - 8 hrs when the oil level on the dipstick fell below 7. After that, the oil consumption increased and is now more in the region of 1 quart every 5 hours. I haven't allowed the oil level to come down to 6 on the dipstick as all of my flights have been more than 2 hrs and I don't want the oil level to drop below 6 at this stage. So, maybe the engine is just blowing the oil out due to the high level, but why the increase in consumtion and now the higher temp?

 

 

 

 

Did you ever get to the bottom of this? I have a new engine with the exact same issue. 

[carusoam]

DM,

you might to update your avatar data...

Listing your model of AC would be helpful... to the people that want to help you...

Best regards,

-a-

[Bob_Belville]

If your CHTs are fine I would have the oil temp prob checked before assuming that the OIlT was really redline which is probably 245F in the vintage models. If the gauge is correct you can check the vernatherm and the seat. 

[dmevans]

On 6/23/2018 at 10:59 PM, carusoam said:

DM,

you might to update your avatar data...

Listing your model of AC would be helpful... to the people that want to help you...

Best regards,

-a-

Thanks. I'll get to that when I have time. I have 67 F with 35 hours on the engine. 

[kellym]

On 5/5/2012 at 8:20 AM, Lood said:

I have about 20 hours on my new engine now and today the oil temp had me rather worried. Right at the beginning, the oil temp ran just about at the top of the green arc, but as the breaking in of the engine progressed, the oil temp decreased. For about the last 10 - 12 hrs, it sat firm at around 180 - 200 deg. On the first 2 hr leg this morning, all was normal. When I took off again for a short 25 min hop to refuel, I noticed the oil temp right at the top of the green arc. OAT was around 10 deg celsius.
We landed, refueled and took off again for another 2 hr leg. I climbed at 120 mph to FL095 and the oil temp was just under redline all the way up. Once settled in the cruise with WOT (19"), 2450 rpm, 80 deg ROP, OAT 7 deg celsius, nothing changed. After about an hour, I went LOP and all other engine temp dropped substantially, but the oil temp stayed at about redline all the way to landing. Oil pressure was very good and all other temps were very cool though and I must add that my original oil temp guage is not very steady but fluctuates all the time. However, it certainly seems to be running a lot higher than it did.

The E and F model with oil cooler on the front chin of the cowling will typically run oil hotter than most aircraft. Oil will run significantly hotter after a hot restart.

210-225 F are not uncommon on those aircraft. As long as you keep oil level above 5,  the quantity won't have much effect on oil temp.  Cowl flap position will affect oil temp...you want to keep them open until you have been in level flight for perhaps 5 min. I don't remember where the colors are on the gauge, so that doesn't tell me much. Actual degrees are more meaningful. Your redline should be 245 F, as that is Lycoming's specification for the IO-360. If temps are going above 220, I recommend lowering the nose and perhaps the power a bit.  My E was always most comfortable at 2500 rpm.  If increased airspeed (slower climb) and cowl flaps open didn't stop the oil temp rise, then I would level off until temp came down unless there were mountains requiring additional climb. I never liked to see oil temp above 225. I would commonly start 3-3.5 hour legs with 6 qts. I added at 5.5 to ensure at least six at start of flight. More than 6.5 and it just wound up on the belly.

 

 

[kellym]

On 5/6/2012 at 8:51 AM, jetdriven said:

I believe the J oil temp is read after the oil cooler.  Other monitors may read before the oil cooler, which is going to be 20-40 degrees hotter.  What's the max "real" oil temp?   285 degrees?   Ins't the max instantaneous oil temperature (inside a main bearing, etc) about 20-40 degrees higher than the oil cooler inlet?   You folks with oil temp problems may not be problems at all.

All Lycoming 4 cyl engines have the temperature probe where the line returning from the cooler enters the crankcase. It is the coolest location. Redline for that location is 245F.

The places where you can install a probe for digital engine gauges are all going to be somewhat hotter, perhaps 5-10 degrees...usually at the front of the engine.

The E and F have a poor cooler location, so it isn't that effective, especially during climb. The J has a much better location. Oil temp is highly dependent on OAT.  If you are flying at 30-40 degrees C above ISO std conditions, you are likely to see 210-220 F oil temp on E or F. Reducing power to 70 or 65 percent will do a lot to reduce oil temp, and maybe cost 5-7 kts. Or just keep cowl flaps open until temp comes down.

Running LOP will help both oil temp and CHTs. If at WOT 6500 ft and up, it will cost about 6 kts over ROP,  or 5-10 min on a 3 hour flt. You also will use less oil if you consistently operate LOP, because the combustion pressures are lower and spread over a longer time, so less blowby to blow oil out.