Getting higher oil temps

Hi all, so it think I’ve read every thread on this site about oil temps in winter, I’m struggling to get any temps over 135-140f, I have the front mounted oil cooler, with the original winter front “installed” so it is 100% covered, i dont have any CHT Or EGT gauge, so don’t know what those are at, from my reading I shouldn’t cover the front cowl openings as it can cause hot spots in the cylinders. Is there anything I can put on the rear between the cowl and the fuse to close it off a bit that would help my oil temps? I have also noticed that on my nose bowl/ cowl, the port side of the plane, the engine access hatch sits off the nose bowl about 1/8-1/4” so cold air can go through there, not sure if that would affect anything. Anyone have any ideas to get my oil temp up? Is there a possibility that my gauge is off? Our temps haven’t even been all that cold, maybe -15 Celsius. Thanks in advance, all help is appreciated.

rear cowl flaps....

you can hinge at forward boot cowl edge and the lay flat behind hinge on boot cowl sides/bottom, then a cable(s) pulls them "open" to 90 degrees to close off exits on sides of rear cowling..... somewhat similar operation on bottom flap, but more like 180 degree travel....

legality of it??????

mike mcs repair said:

rear cowl flaps....

you can hinge at forward boot cowl edge and the lay flat behind hinge on boot cowl sides/bottom, then a cable(s) pulls them "open" to 90 degrees to close off exits on sides of rear cowling..... somewhat similar operation on bottom flap, but more like 180 degree travel....

legality of it??????

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i used a fixed version of this on a Super Cub in Fairbanks and on a Top Cub in northern MN. Works well, but unless you’re in really cool temps, adjustable like Mike described would be best.

Paint em flat black and nobody will notice

MTV

It's all just adjustable duct tape lol.

Web

fishingh said:

from my reading I shouldn’t cover the front cowl openings as it can cause hot spots in the cylinders.

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I think you misunderstood this. If you tape or otherwise block air flow through/between any of the cylinder fins, then yes you can create hot spots on the cylinders.
If you place a cover over part of the cowl inlet openings, you are just reducing the air mass flow through the entire engine compartment. By reducing the mass flow the cooling action of the air will be reduced. Thus higher temps. Individual hots spots will not be produced just an overall temperature rise.

Try taping over the inlet openings, one tape at a time until you find the temperature to your liking. Then just leave it or make a nice cover plate of the right size. Cessna makes plates for this purpose which they include in what they call a "winter kit".

There’s an outfit in Bozeman that has a couple of Super Cubs used for game tracking with adjustable cowl flaps at the cheeks. Pilot told me they were approved?? This was about 8 or 9 years ago. Maybe Mike knows/can find out?

mam90 said:

There’s an outfit in Bozeman that has a couple of Super Cubs used for game tracking with adjustable cowl flaps at the cheeks. Pilot told me they were approved?? This was about 8 or 9 years ago. Maybe Mike knows/can find out?

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That would be Roger Stradley’s. Out of business and planes were sold. I’ll ask around.

I was told by the instructor at Lycoming’s Piston Engine Service School to be very careful covering cowling air inlets. He said his concern would be creating turbulent air flow over front cylinders. I have no idea if that was just manufacturers paranoia, but his suggestion was to somehow block off part of the area where air EXITS the cowling instead.

Those side cheeks on the Cub cowling actually move quite a bit of air. We installed nut plates in edge of firewall, and built block off plates that fit up against side cowl doors. Those plates just screwed to the firewall with four machine screws, and took all of a few minutes to remove. Flew in some mighty cold temps and engine room stayed toasty.

As I noted earlier, paint em flat black. Cant see them till you open cowl door, and then they look like they belong. An adjustable version would be better.

the guys at Phillips Field in Fairbanks had an STC (maybe FA) for a cowl flap for Cubs as well. I never flew one with that, but at - 40, you need something, and you can’t block off the entire cowl inlet....

MTV

What about using plastering mesh over the inlet opening? This would tend to slow down the airflow without blocking it. Restricting either the inlet or outlet would produce a similar effect. Mike's suggestion of blocking the side cowl exits is a good one. I have no interior in my Cub. When I place my hand on the inside of the fabric on the side ahead of the door it is very warm, even when ambient temperatures are low. I believe it actually helps with heating the cabin.

To add to this, Cessna provided a “Winter Front” kit for the 185. I flew a 1985 185 that came with this kit in Fairbanks and north. The kit consisted of three plates: One that covered each cowling air inlet, and one that covered the Air Induction. The cowl inlet covers had small openings for air flow, and “ramps” to direct the flow. The block off plate on the induction had a round hole in center.

First winter, when it got good and cold (-30) I installed those plates and headed north. Now, the problem with that part of the world is that when surface temps are very cold, temps aloft are generally warmer, often quite a bit warmer. So, I climbed out to clear the White mountains and CHT was getting HIGH. So, stayed low, down in cold air.

And the other feature of those block off plates was they almost eliminated air flow through the cabin heat system. So, now you’re down in the -30 air to keep engine cool, freezing yer butt off and trying to keep windows clear......duh.

So, removed the cowl inlet block off plates, duct taped over the oil cooler (fully adjustable, of course) left the induction plate installed and flew that plane down to -40 fairly regularly. The induction plate is designed to restrict inlet air volume of very cold air, to prevent over boosting engine. Those engines can make a lot of power with -40 density air. The restriction causes the alternate air door in the induction (spring loaded closed normally) to open, mixing warmer air from inside the lower cowl with that very cold inlet air.

Of course, the 185 has cowl flaps...the logical and effective means to restrict flow through a pressure cowl.

Those damn cowling block off plates from Cessna gathered dust in a corner of the hangar. May still be there.

MTV

I too tried the Cessna winter plates on my 185 following their temperature instructions. Actually it was 10 degrees cooler. The engine ran very warm, enough to make me nervous. As soon as I arrived at my first destination, they came off, going back to the attic. A larger opening would have been acceptable. I also have extra louvers in the side cowl which are very effective in reducing temperatures. Even with them, the Cessna winter plates were too warm.

Hey guys, I’m still having an issue with my oil temps, oat have been bitterly cold here hovering around -35c, I’ve completely blocked off my oil cooler, I’ve checked my oil temp gauge, as well as my vermatherm, and have plates blocking the rear exits on either side of the cowl, I am still unable to get over 130-140, and I’m barely getting up to these temps, next up is taping up my cowls, I’m not sure what else to do, I don’t have cht gauges. I tried foil tape on the cowling openings and it just ripped completely off. I don’t want to use any duct tape or gorilla tape as my paint is fresh and don’t want to deal with the glue, planning on trying a vinyl tape tomorrow, any other suggestions or things to check?

I do not own a Super Cub, but I would say that's pretty good for a OAT of -35C!

On my plane (CC EX-2 ground looping legacy death gear plane) with the 340ci, it has a massive oil cooler. With it taped off in winter, I'm happy with 160F (OAT 29F).

Not sure if it is possible raise the oil temp much more at those OATs. But there are very experienced people here that can chime in.

Have you tried metal tape over the front of the cooler itself? If you have the room try a simple wrap of fire resistant material around the oil cooler itself. Change oil at 25 hours. DENNY

DENNY said:

Have you tried metal tape over the front of the cooler itself? If you have the room try a simple wrap of fire resistant material around the oil cooler itself. Change oil at 25 hours. DENNY

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yea, it’s taped on both sides, didn’t make a difference. Lol

When flying with an oat of -35C I would say you are fortunate to get the oil up to 130-140.

A couple of untried thoughts, since I wouldn't even consider flying in those temperatures.
Disconnect the oil cooler hoses and connect the two together, thus eliminating the cooler from the loop. You do not need the cooler at those temperatures.
Make a blanket which fits around the sump of the engine. The air flowing past the aluminum sump is cooling the oil. That is a big heat sink. Long ago there were special "jackets" made for this purpose for the kidney tanks on the Continental engines.

I agree that at -35 C that’s probably as good as it gets. I’ve flown Cubs and Huskys both at those kinds of temps, and what you’re reporting was what I saw. It’s certainly not ideal, but I just changed oil more frequently and kept flying. I certainly never flew recreationally at those temps, and there had to be a REALLY good reason to do so, but as I told our aircraft managers in Anchorage (referred to as the “Banana Belt” to those residing north of the Alaska Range), if I didn’t fly at colder than -20, we wouldn’t get much done.

MTV

The good news is that at those temperatures there’s very little water content in the air. You are essentially flying in the desert.

Dnh98221 said:

The good news is that at those temperatures there’s very little water content in the air. You are essentially flying in the desert.

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Indeed, but there's still moisture in the fuel.

MTV

And water in the crankcase from any combustion blow-by....pull the dipstick after a flight and note the steam when it's cold

Gary

skywagon8a said:

When flying with an oat of -35C I would say you are fortunate to get the oil up to 130-140.

A couple of untried thoughts, since I wouldn't even consider flying in those temperatures.
Disconnect the oil cooler hoses and connect the two together, thus eliminating the cooler from the loop. You do not need the cooler at those temperatures.
Make a blanket which fits around the sump of the engine. The air flowing past the aluminum sump is cooling the oil. That is a big heat sink. Long ago there were special "jackets" made for this purpose for the kidney tanks on the Continental engines.

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I have my -12 set up so at -40C/F I can get 170F on oil temp.


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Maybe you need to go fly your Cub in Florida for the winter


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Haha, I’m pretty lucky to be able to live where I live and frankly I think it’s one of the most beautiful areas in the world, The winter gets a bit old sometimes but I wouldn’t change that for anything, we’re on the up and up temperature wise here so I’m putting this oil temp issue behind me and I’ll deal with it next winter when the issue arises again. Would running a lighter weight oil get me higher oil temps? Can I block off those 2 little exits on either side of the lower bottom cowl? I’m not sure what else to do after that, I’m ordering a CHT gauge so i know where those are at before I start restricting anymore airflow. Thanks everyone for your help. Truly appreciated.

Scooter7779h said:

I have my -12 set up so at -40C/F I can get 170F on oil temp.


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For reference, I have a Dan’s Aircraft controllable box on the forward side of the rear baffle where the oil cooler is mounted, then fabricated a blocking plate for the rear of the oil cooler with holes that are in the plate that can be covered with 200mph 3M aluminum tape depending on temperature. I just adjust cable on dash to maintain 180F oil temp year round. Usually I put rear plate on in October, and remove in April so the controllable box can stay in range to maintain 180 in cruise or climb.


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Scooter7779h said:

For reference, I have a Dan’s Aircraft controllable box on the forward side of the rear baffle where the oil cooler is mounted, then fabricated a blocking plate for the rear of the oil cooler with holes that are in the plate that can be covered with 200mph 3M aluminum tape depending on temperature. I just adjust cable on dash to maintain 180F oil temp year round. Usually I put rear plate on in October, and remove in April so the controllable box can stay in range to maintain 180 in cruise or climb.


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Got any pics? Do they still make the oil cooler box?


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RaisedByWolves said:

Got any pics? Do they still make the oil cooler box?


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I’m out at my cabin covered up in snowstorm. I believe Dan still makes the box, it’s not STC, need FA. Stoddard’s has carried them.


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