The International Cessna 170 Association

Our 170 flew for the first time in 6 years. I am currently working on my private certificate so I had to let my instructor do the flying. He was working the engine pretty hard and he said that the oil temp got up to about 185-190. From what I understand this is normal for a C145-2/o-300? What are your average oil temps?

Those temps are just fine. With SAE 50 oil, the temp is allowed to go to 240 per the engine type certificate. (Many other models of engines/airplanes strive to get their temps up to the level you are experiencing in order to get the water vapor out of the oil.)

51C170A wrote:Our 170 flew for the first time in 6 years. I am currently working on my private certificate so I had to let my instructor do the flying. He was working the engine pretty hard and he said that the oil temp got up to about 185-190. From what I understand this is normal for a C145-2/o-300? What are your average oil temps?

Guess that depends on where you're operating. That is cold for mine this time of year, flying in the midwest USA. Almost always over 200 during summer months.

OAT is always a factor, but even in Texas yesterday when the OAT was 95-F my oil temp only got to 190- 200 on an ordinary flight. Certainly flight training might run it up a bit more, but in any case, the temps described are certainly well within limits.

I've been tracking oil temperature ranges for many years. Here is what I've found to be generally true.

All B models with stock cowl and lip will run hotter. By that I mean over 200 and many near 225 on hotter days in the south.
A models and '48s with stock cowl and lip run between 160 and 180.

There are anomalies of course. It would seem more than one A model, usually a 51, will run hotter with no explanation.

The biggest factor after general baffle condition that I have found is the size of the lip on the lower cowl. '48s and early, if not all A models, have nearly a 3" lip standard. All B models have a 3/4" lip standard. Many early 3" lips including the one on my early A model have been reduced in size. Mine for example is 2" which was not a Cessna configuration.

Thanks for all the reply's. The oil temp was the only concern he had after the first flight (about 35-40minutes) the OAT was only about 75. We will just have to keep an eye on it and see what happens.

Aryana wrote:...Seemed silly to me to blast the probe area with cooling air since IMO it does more to artificially lower the indicated temp than really cool the oil. Using one of those laser temp gauges we unscientificly validated the oil temp didn't change, just the indication on the gauge. ....

Since the probe is immersed in oil, if the probe is cooler, the oil is cooler.

Where are the instructions for modifying the blast tube? Thx.

Thx. I've never been able to locate the installation instructions. Nor does it appear as though my blast tube has been modified.

My 48 runs 180 - 190 max on even the few hot days here in Canada (90F). I have the 3/4 lip and had the stock lip, approximately 2" and it ran the same temps with the large lip. The only thing the lip does is slow you down. Temperatures depend on to many variables to worry about. As George said just respect the max temp and anything goes.

Thanks for posting. Anyone know the appropriate method of modifying the blast tube?

Aryana wrote:Ok, here are the F&M install instructions.

"X. If air was provided to the oil temperature probe via a blast tube, the blast tube will need to be modified to provide air to the new location of the oil temperature probe."

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Also if you're running straight 100 weight oil in 40F+ ambient, your oil temp redline is increased from 225F to 240F. Surprised no one has mentioned that.

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What didn't I say?....

gahorn wrote:Those temps are just fine. With SAE 50 oil, the temp is allowed to go to 240 per the engine type certificate. (Many other models of engines/airplanes strive to get their temps up to the level you are experiencing in order to get the water vapor out of the oil.)

48RagwingPilot wrote:Thanks for posting. Anyone know the appropriate method of modifying the blast tube?

Overheard this weekend (name withheld to protect the innocent) was a modification of a blast tube with an old (PMA- passes my approval) lawn chair. Same size tubing and already bent at the correct angle.

Ryan Smith wrote:

48RagwingPilot wrote:Thanks for posting. Anyone know the appropriate method of modifying the blast tube?

Overheard this weekend (name withheld to protect the innocent) was a modification of a blast tube with an old (PMA- passes my approval) lawn chair. Same size tubing and already bent at the correct angle.

I love that. I was looking over a friend of mines Championship winning hot rod (British oval dirt racing) and asked him what steel he had used for the suspension arms (He is obsessive about unsprung weight). I said "is it 4130 ?" He replied "no, it is table steel". I said "whats that?", he said he had cut it off his wife's garden table.