The Cessna 120-140 Association Forum

Hey guys,

I figured I would throw the question out to the community first to see if anyone has shared my experience. My “new to me” Cessna 140 with a C-85-12f has been running fairly consistent high oil temps with good pressures that are just on the high side. The oil temp will reach around 220-225f in climb before I push it over and let it cruise out. This may allow me to climb 2-3000 feet on a good day before I need to take action (That puts me around 7500-8500 MSL.) Unless I sustain that cruise for periods of 45 minutes or more, I don't see much of a decline in temp, it may come down to somewhere between 218-223f. Regardless of the temperature that I’m operating at (between 55 and 85f OAT) the oil temp always hovers around the same place with the exception of descent’s into landing, I do have a 15f drop in temp on descent.

Are there any tricks to getting oil temps down?

I currently run Aeroshell W100 plus which covers the OAT temp range I operate in. Has anyone swapped over to W120? I’ve considered this but, with oil pressure sitting at 45 psi in cruise, I’m not sure if the added viscosity would help me or hurt me.

Or finally, is this just a normal temp range for a C85 at higher altitude?

Thanks,

Joe

Have you confirmed the accuracy of your oil temperature gauge? I boil water and put the probe in it. At sea level it should read 212 degrees Fahrenheit.

I’ll check it out tonight or tomorrow and report back the results. I would hope its something as simple as the temp sensor but, I have my doubts. When I flew it back from the east coast it seemed to be closer to the 210f range. We will see though.

6298 wrote: ↑Sat Jul 31, 2021 4:32 pm Have you confirmed the accuracy of your oil temperature gauge? I boil water and put the probe in it. At sea level it should read 212 degrees Fahrenheit.

Looks like that narrowed it down to the probe and gauge. At my current pressure I calculated that I should’ve seen boiling at 202f. My gauge was showing 215f. That makes me feel better about the temps. Now to source the part.

Thanks!

Does your aircraft have blast tube directed on to the oil screen? It's been my experience that most aircraft will run 100 over OAT.

Baffle seals...

Also, do you have the little bits from the "summerization" kit? They and the blast tube make a big difference.

Ive got the baffle seals but, I don't think my blast tube is rigged correctly. If I remember right, mine is directed to flow onto the oil reservoir, not the suction screen. I will check this afternoon, haven’t had as much time as I would like to be in the hangar with all of the flooding we’ve been getting in Utah.

6643 wrote: ↑Mon Aug 02, 2021 7:54 pm Baffle seals...

Also, do you have the little bits from the "summerization" kit? They and the blast tube make a big difference.

What other “bits” are there? I have the shield in front of the oil tank, which I’m told is pretty rare, but am not aware of any other bits. Baffling appear to win decent shape and I have the small bits under the cylinders too.
I’ve had higher than normal oil temps since I’ve had the airplane, and of course pressure goes down as temps go up.
Last flight running 15W-50 Aeroshell my oil temp was slightly over 200 and pressure was 28, which of course is less than the 30 min.
However when the oil is cooler like during run up my pressure is slightly over 40, so it’s not a pressure relief shimming issue.
I’m thinking about going to 60W oil for the Summer heat as I’ve run straight 50W before and not much difference in it and the 15W-50.

The inner cylinder baffles have extensions that close off the area at the cylinder base.

The blast tube should be directed at the center of the oil filter screen housing. The summerization kit includes baffles between the cylinder barrels on both sides. They are shown in the options section of the parts catalog, available on the main site under Resources->Documents.

The baffles have to seal against the cowl, especially across the top in the back and around the sides and front at the engine's "waist".

I have a C90 with tight baffling, summerization kit, blast tube and the tank baffle. There is nothing special on the lower lip of the cowl. I don't think I've ever seen the temp higher than 180.

What is your compression and oil consumption? How many hours on the engine bottom end? You should be able to maintain at least 30 lbs of pressure up to 220 degrees oil temp.