The International Cessna^® 170 Association

Aryana wrote: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

Bruce Fenstermacher wrote: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 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

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 the oil temp gauge you have is OBSOLETE in that it has a red line a 225F.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.

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

Guys,
I've patched and tightened my engine baffling, switched to straight 50 weight oil and about to order the recommended oil temp gauge pictured below. Aircraft Spruce offers a "C of C" for an extra $15. Is this document necessary?
Thanks, JP

Aryana wrote:No, it's not needed for Part 91 operation. It does however improve the performance of your 170 as a result of the weight savings from your lighter wallet

Thanks Aryana! I'll skip the C of C and live with the weight penalty.
JP

I have the same problem during the summer. I used a digital laser thermometer and found that the gauge reads 25 deg hotter than the actual temperature. So the temperature was actually within limits.

nmflyr wrote:I have the same problem during the summer. I used a digital laser thermometer and found that the gauge reads 25 deg hotter than the actual temperature. So the temperature was actually within limits.

Oil temp? How did you measure it, exactly?