High Oil Temp?

[Onewinglo]

I made a precautionary landing today due to higher than normal engine oil temp. I was on the 3rd leg of a 500 nautical mile trip home and climbing at about 80 mph to 4500' with a leaned mixture (just rich of peak). My oil temp needle normally rest atop the "L" in OIL. Today it was in the middle of the red area.
I diverted to a nearby airport and checked the oil, cowling, and looked over everything carefully. Oil level was at 7 1/2 quarts so I added 1/2 quart, and everything else looked normal. I maintained a very shallow climb with airspeed of at least 90 mph upon departure but the oil temp never got lower than is shown in the attached image. After landing at my home airport the needle was back atop the "L" as I taxied to my hanger. The oil temp gauge was replaced last October before I bought the plane.
I bought my 170 in November and today was the first really hot day I have flown.
Is this normal or do I have an issue to resolve?
Thanks, JP

[blueldr]

I would strongly suggest you get an oil temperature gage system that reads in degrees. They're not all that expensive and the can considerably reduce the worry factor.

[Bruce Fenstermacher]

The blast tubes as mentioned have to point at the oil screen area of the accessory case at the lower arrow. If it isn't the oil temp will likely read high.

Blast tube.png (14.65 KiB) Viewed 16811 times

You have an A model. I'm finding most run cooler than B models. Curious how deep your cowl lip is between the red lines in the picture below. Should be about 2". If it is only 3/4" that is why your oil is running as hot as B models seem to do IMO.

Lower cowl lip.png (10.18 KiB) Viewed 16811 times

[Onewinglo]

When it starts getting hot, mixture rich helps a lot.

Exhaust leaks near push rod tubes can hear up your oil. Proper engine baffling installation has a major effect too. Also what is the condition of your cold air blast tubes that aim at the lower acc case? Pictures are good for us to help. Need to see where they are pointing.

I'll get the baffling checked and send some pictures of the blast tubes.

Do you have a F&M oil filter installed? This matters because it relocates the oil temp bulb aft, and the blast tubes need to be moved aft as well to maintain the proper temp indication.

I do have an oil filter kit but I do not the brand. I'll post pictures of the filter and blast tube location.

You mention your oil gauge was replaced. Yours looks original. I don't know where you can buy that style gauge new, but I've been wrong before. If there's a source to buy an original gauge like that, I would really like it so I can get one!

The logs state the gauge was rebuilt. I was mistaken about it being new.

Also what oil are you using? Is it 100W? 100W allows for an increased redline of 240F, which doesn't do you much good since that's beyond the range of your current gauge.

I'm using Phillips 20/50 because that was in the plane when I bought it.
Thanks very much for the reply!
JP

[Onewinglo]

I would strongly suggest you get an oil temperature gage system that reads in degrees. They're not all that expensive and the can considerably reduce the worry factor.

I agree! I need a gauge that reads in degrees.
JP

[Onewinglo]

The blast tubes as mentioned have to point at the oil screen area of the accessory case at the lower arrow. If it isn't the oil temp will likely read high.

Blast tube.png

You have an A model. I'm finding most run cooler than B models. Curious how deep your cowl lip is between the red lines in the picture below. Should be about 2". If it is only 3/4" that is why your oil is running as hot as B models seem to do IMO.

Lower cowl lip.png

Bruce I'll check out the blast tubes and cowl lip when I get back to my hanger this weekend.
Thanks for the help!

[ghostflyer]

Well in my humble view you are using one of the best oils around . We have tried every manufacturer and Phillips multi grade does a great job. A couple of years ago had a " BIG" issue with Lycoming with oil bypassing the rings in a brand new engine. Tried about 5 different brands and had oil analysis done on the engine every 20 hours. When BP started praising Phillips oils I sat up and listen with interest . I would be fitting a remote spin on filter unit with a digital temperature gauge . You can't afford to have the fan stopping , the pilot then sweats. I have looked at it this way , the oil has to be a certain temperature for the correct operation of the engine . Both the oil manufacturer and engine manufacture will tell you what the oil temperature should be for safe flight . "Maybe having a blast tube facing the oil temperature bulb will give a false reading of what the oil temperature really is . By all means cool the engine the way the manufacturer indicates It's the oil temperature in the engine what's important . I would go for a fly and then land and check the sump temperature with a hand held digital temperature reader.

[KS170A]

By all means cool the engine the way the manufacturer indicates It's the oil temperature in the engine what's important . I would go for a fly and then land and check the sump temperature with a hand held digital temperature reader.

What would reading the temperature of the sump tell you? Nothing of value relative to the OP's question. There is not any data available that would correlate the known temperature measured at the bulb compared to the external temperature of the sump, or anywhere else for that matter. Cessna and Continental decided on a particular way to measure the oil temperature during their certification processes, with engineering data to back them up. They probably could have used many other methods to obtain the readings and limits. One thing is for certain though...excessive heat is an engine's #1 enemy.

Hot oil is a common complaint, especially in warmer outside air temperatures. Shallower climb angles, proper cooling air distribution (properly aimed blast tubes, tight baffling, etc), or even some after market modifications to add external oil filters (already mentioned) or oil coolers, are all ways to mitigate high oil temperatures.

[flyboy122]

The first thing I would do is test the gauge/probe. Get a 1 qt. metal can, a hot plate, a quart of oil, and your wife's candy thermometer. Put temp bulb in oil in can while being heated with the hot plate. Use the thermometer to check against the gauge. You can then calibrate the gauge and know what temps green/red/O/I/L really are. When done, don't forget to apologize to your wife and buy her a new thermometer.

Next, read the engine operator's manual and check what the recommended temp range is. With all due respect to the internet experts, I'll go with the OEM's recommendation.

If after all this you are outside the range, like the other guys said start looking at baffling, blast tubes, oil, etc.....

BTW, I would highly.....highly recommend a gauge with numbers, and a spin on oil filter. Neither is a lot of money for what good they provide.

DEM

[jrenwick]

When it starts getting hot, mixture rich helps a lot.

This is really important. I've come to regard the red knob as the engine temperature control. Also, avoid extended climbs at low airspeeds on hot days. And expect the oil temperature to be close to the red line when climbing on hot days; it's normal.

[Bruce Fenstermacher]

If you swap out the oil pressure gauge know that you must swap out the fitting in the engine that matches the fittng on the gauge. They are a set. See the red arrows.

oil pressure gauge.jpg (48.03 KiB) Viewed 16651 times

Some adapters don't match every bulb nut and leaks will be the result

[flyboy122]

Hi DEM, I'm curious what you're referring to regarding recommendations from Internet experts? haven't seen anything in this thread contrary to TCM's operating range listed in their type certificate E-253.

Hi Aryana,

Neither have I, but this isn't the only forum out there and I bet if you google "Continental Oil Temp" you'll get a lot of hits! I actually went through a high oil temp episode a couple years ago on the Lycoming in my Dad's RV-8. By the time I got it on the ground it was, ahem.....hot. For the heck of it I googled it to see how bad I cooked the engine and 3 hours later came away more confused then when I had started. Then I opened up the Lycoming manual and breathed a sigh of relief.

DEM

[Onewinglo]

The blast tubes as mentioned have to point at the oil screen area of the accessory case at the lower arrow. If it isn't the oil temp will likely read high.

The attachment Blast tube.png is no longer available

You have an A model. I'm finding most run cooler than B models. Curious how deep your cowl lip is between the red lines in the picture below. Should be about 2". If it is only 3/4" that is why your oil is running as hot as B models seem to do IMO.

The attachment Lower cowl lip.png is no longer available

Bruce, I took a good look at my blast tubes today. The left tube looks well positioned to cool the oil temp bulb.

The right tube looks as if it's air flow may be at least partially passing below the oil filter adapter. This is a view from below.

I did work with my baffling today and got a tighter fit and found a couple holes that need tape.

Can anyone tell me which oil filter adapter I have?

My cowl lip is about 2" btw.
Thanks to everyone for the help!
JP

[GAHorn]

You've got the TCM/Cessna adaptor.

FIRSTLY... the oil temp gauge you have is OBSOLETE in that it has a red line a 225F.
The engine type certificate (as Aryana posted) allows oil temps to 240F...IF...BIG IF... you use SAE 50 STRAIGHT weight oil. That precludes the oil you're using.

If you were to do a search thru these forums (admittedly a tedious task) you'd see where this has been discussed many many times.
The engine mfr'r did not want to use external oil lines to avoid the Lycoming problems of fractured lines.
TCM kept their oil system internal and a cam placed low, near the sump, creates a situation where oil-return lines from the rocker boxes run downstream of the cooling air for the cyls. If your exhaust system leaks hot gases onto those pushrod tubes they will heat up the oil inside that is returning to the sump.

But...QUIT WORRYING ABOUT YOUR OIL TEMP. It's only running 220 and that's not excessive regardless of the oil you're using.

Make certain your engine cooling baffling is tight, no leaks, no exhaust leaks at the pushrod tubes, use straight SAE 50 wt oil..., and remember your oil temp limit is 240F...not the redline 225 your present gauge is indicating.

[Onewinglo]

George,
Thanks for the reply. I have done a lot of reading on our forum about this issue and I'm feeling better about it.
Today I bought Aeroshell 100W and a new filter so I'll switch to 50 weight oil this weekend. I tightened my baffling today and identified two small leaks to repair this weekend also.
Next I'll buy the new oil temp gauge as recommended. I just need to measure for the correct length.
Thanks again for the help!
JP