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Oil Cooler Air Deflector Thingee

PostPosted: Sat Jan 13, 2018 4:42 pm
by alan
I don't know how you guys up north do it, but I've been using a piece or two of duct tape to block the flow of air through the oil cooler when the temps drop. Living down by Houston, there aren't that many days of the year when it's been a problem. Lately however, there have been nights in the mid 20's and days in the 30's and low 40's. The Rotax doesn't like that. One 45deg day I flew for that $100 hamburger and the oil temp rose no higher than 160deg. I didn't think that was a good idea, but it took me several days to think of a way to improve this. If I can properly post the pictures, here is my solution.

The first picture is what it looked like before, with one strip of duct tape. The hole is 7" wide x 4-1/2" high.

The second picture is inside the cowling with all nut plates riveted on and both plates attached. The main piece is 9" x 6-1/2". It's hole is 5" x 2-1/2". The last piece is 7" x 1" and leaves a 5" x 1-1/2" air hole.

The third picture is with just the main plate attached and the screws for the second piece just keeping bugs off the threads

The fourth, and last, picture is with both plates installed leaving only a 5" x 1-1/2" hole for cooling. This is the way it was flown today. The plates are 6061T6 .040".

Today, the low was 31deg. It was 40deg when I took off for the test flight. The oil temp reached 170deg in about 10 minutes. I left the airport traffic area and flew on down to Texas Gulf Coast Regional (LBX) for that $100 seafood. Yum! The temp had risen to 44deg by noon and the oil temp on the way home went up to almost 180deg. This was with both pieces installed.

I think it turned out well. I need to figure out at what temp I can fly without the second plate, but that shouldn't be too hard, I hope.

I'm sure y'all can figure out why I painted it red.


Re: Oil Cooler Air Deflector Thingee

PostPosted: Sat Jan 13, 2018 6:06 pm
by FlyerChief
Hi Alan,
I installed one of these on my Highlander and I am completely impressed with how well it works... stable oil temperatures and quick warm up.

Here's one of the links to a past thread...


Re: Oil Cooler Air Deflector Thingee

PostPosted: Mon Jan 15, 2018 9:40 am
by alan
I considered the thermostat years ago but there are some experts on the Rotax forum who said that the bypass valve never closes all the way preventing some oil from cooling. Since there are lots of 100deg days where I fly I need max cooling.

It's possible the thermostat you referenced is a different one. If so, too late.

Thank you for the feedback.