oil temp

[gpilot.gary]

I have had my 170 (1948) with o300 ( metal wings) for a little over a year. I am noticing oil temps running at red line most of the summer . Of course I live in southern utah and it is 90-100 all summer. What is the solution? or "a" solution.

[Bruce Fenstermacher]

No solution needed. The oil temperature is within limits. Nearly all 170s run with these 'Hot" oil temperatures.

Since you are concerned you should first determine that your temperature gage is reading correctly. This can be done by removing the bulb of the gage from the accessory case a putting it in heated oil or water of a known temperature.

What red line are you talking about. Bet it is a read line at 225 degrees. If you use straight 50 weight oil the red line is 240 degrees. Use straight 50 weight and fly around all day at the "red line" of 225 knowing your 15 degrees under the real "red line".

[Robert Eilers]

I found my 52-170B in Phoenix. Shortly after purchasing the airplane, I noticed the air hole beneath the prop - for the oil tank - had a larger opening than other stock 170s. The work done to enlarge the air hole was professionally done. During hot Northern Calif. summers - 100 degrees + - then oil stays around 200 degrees. Of course, in the Winter I find it necessary to tape the oil tank air hole.

[blueldr]

In controlling the oil temperature on a Continental C-145/O-300 engine, it is essential that the baffling be in good condition and properly installed since part of the designed oil cooling is accomplished by air cooling the hot oil returning to the sump via the push rod housings.

[GAHorn]

And keep the exhaust system leaks repaired at the riser flanges.

[N2625U]

Can't remember where I found this. But it does make sense explaining the O300 & oil cooling.

Continental was opposed to external oil lines on their engines, and the "C"-series of engines was designed without them. Although an oil cooler design was produced by TCM (Continental Motors Corporation), Cessna was opposed to using it, probably for price considerations. So the C145/O300 installed in a Cessna runs hotter than the same engine in a Fairchild/Stinson/etc.. It also runs cooler in a Swift due to the updraft cooling.
Why would updraft cooling help? For one reason, the oil sump gets a nice first-chance at the cool air. But another major reason is because the pushrod tubes, being sheet-metal, and because the Cont. engines pump relatively high quantities of oil to the rocker boxes (much more than the Lycomings because of the better hydraulic lifters that Cont. uses) that subsequently runs back down those tubes to the sump, ...those pushrod tubes act as oil coolers and on the updraft cooling systems they also get a first-shot at the cooling air.
On a downdraft cooling system such as on our airplanes, the pushrods aren't in such a good position, as they sit downstream of those nice warm cylinders. Nonetheless, they still perform a function of cooling. And that's the problem.

If your exhaust flange gaskets leak, or if your exhaust riser clamps leak and spray hot exhaust onto your pushrods, a surprisingly large increase in oil temperature will result. So look for signs of exhaust blowing on your pushrod tubes.

There is not too many reasons for a 170 engine (C145/O300) to suddenly start running much hotter than 210-220 F. The most common reason for a sudden change is a faulty gauge. The next most common reason is a leaking exhaust flange. The third reason is faulty cooling baffles. The fourth reason is a broken or stuck piston ring, which can be detected with a compression test and subsequent blow-by into the crankcase.

Even a C145/O300 engine that has run all it's life with oil temps at or near redline will make TBO as often as other engines that run much cooler. The high oil temp does not seem to hurt the C145/O300 as much as it does some other engines. One reason for that is due to the location of the oil temp probe. Our oil temp probes are located at the oil inlet to the engine (at the oil screen.) Most other engines measure their oil temps at the outlet of the oil cooler. That's why they commonly indicate oil temps in the 180 degree range. Therefore it's not appropriate to compare the C145/O300 engine oil temp indications to other engines. If you'd measure the oil temps of most other engines at the inlet of their oil coolers their temp readings would be frightening.
So,...run SAE 50 wt oil in warm weather (above 40 degrees F) and SAE 30 in cooler weather (below 40 degrees F) order to take advantage of the higher 240 degree oil temp redline. (I've never seen SAE 30 aircraft oil, personally. Interestingly, SAE 40 oil is never approved for 240 degrees in our engines, apparently because it's not approved for use below 40 degrees F.)

[n2582d]

It's the wrong time of year for this--at least for those 170's north of the equator--but it looked like an interesting idea: Oil Filter shroud

oil_cooler_001.jpg (16.09 KiB) Viewed 5817 times

If I was to do this I would make sure there is no chaffing between the shroud and the filter--maybe some rubber channel on the edges of the shroud.
Sill's Aviation has one that's more high tech:

sasweb072.jpg.w300h225.jpg (90.47 KiB) Viewed 5817 times

[mod cessna]

In Alaska i have the opposite problem. All my baffling is rebuilt and every little air leak sealed. Below about 50F, air temperature, my engine will never get above 180f oil temp. I can get 190 max in a climb. My oil sump intake is always plugged. Now the weather is way colder then 50f and its time to install my inlet covers. Last year my covers came on a sticky roll. This year i hope to install some similar to the ones produced by Cessna. Has anyone made covers that incorporate a scoop of sorts to give the heater some air flow??

[HA]

mod cessna- I made up some winter fronts last year and they worked well - I cut a "flap" in the bottom of the one in front of the heater intake and bent that flap back about 45 degrees - it acts like a scoop almost and the heater gets good airflow. sorry I don't have a picture but I'm sure you get the idea.