The Cessna 120-140 Association Forum

I have what has to be a factory part on my engine, it’s a shield that wraps around the front of the oil tank, presumably to block airflow. I’ve not seen it in any parts manual, and today the IA who I had complete my Annual who is supposedly a little airplane expert commented that he had never seen one.
Does anyone know anything about it? Is it some kind of winterization kit?
My oil temps do run a little higher than I think they should, where most seem to run about 100f above ambient, mine seems to run about 120 above, and when the temp gets to about 200, my oil pressure gets closer to 30 than I like, so I’m thinking I should remove this shield, but would like some info on it if anyone has any before I just take it on myself to remove a part off of a Certified engine.

There is a factory baffle that channels air around the oil tank. What you described sounds like that part. It is in the parts manual. Your oil temp shoul run cooler with it installed.

If you don’t want it I’m happy to buy it from you!

Yes, if you remove it the tank is exposed to the warm, low pressure air of the lower cowl. With it in place , cool pressurized air from the plenum under the lower spine of the engine case is directed over the surface of the front of the tank to aid cooling the oil.

It is not part of any kit, pn 0450166. Interestingly, it is not required on 140's after sn 14305, but is on all lower serial numbers, and on all 120's regardless of serial number. I believe this coincides with the change to the C90 in the 140.

Currently it’s off because I just changed the oil tank gasket chasing an oil leak, but upon fixing this leak I’ll reinstall it.

Those tanks are prone to cracking around the flange. Also, over tightening to cure a leak often warps the flange. The tab that bolts the fill neck to the engine case needs to be shimmed with washers so it doesn't try to bend things.

Randy Thompson may have more hints.

6643 wrote: ↑Sat Dec 05, 2020 7:43 pm Those tanks are prone to cracking around the flange. Also, over tightening to cure a leak often warps the flange. The tab that bolts the fill neck to the engine case needs to be shimmed with washers so it doesn't try to bend things.

Randy Thompson may have more hints.

Thanks, the oil tank flange is thick and would be tough to bend I would think. However the bolts were over tightened when I removed them, the silicone gasket I ordered spec’ d 15 in lbs torque, as the studs are drilled for cotter pins I tried to get close to that torque anyway.

Those nuts are hard enough to get on. Try MS21043 self locking, reduced hex 800 degree nuts. A 5/16 socket or wrench will fit on them and there's more clearance with the neck of the tank, to boot.

It’s already on, the nuts weren’t that hard really, I cut my teeth in helicopters and those things can be a real bear to work on, you learned tricks to use like sticking aluminum and steel washers together with superglue because there had to be aluminum against the airframe and steel against the nut, that way any dissimilar corrosion happened to the washers, but it made things difficult at times.

I'm lazy! So, if you glue the washer to the nut, how do you then attach the nut to your fingertip?