Thorp Air Command - T18.net

Hello All,

I'd like some help diagnosing an oil cooling issue. I think my oil temp is running too low and that the culprit is the attachment point of the oil cooler to the accessory case.

I have an O-320 accessory case and there's a Vernatherm in the oil pressure screen housing. I think the oil return line, from the cooler, is attached correctly to the left, and higher than, the oil pressure screen housing. The oil line to the cooler is attached in the middle of the accessory case, maybe half way up from the bottom of the engine, so to the right and below the oil pressure screen housing. I think this is the incorrect attachment point when a Vernatherm is installed.

Can anyone confirm that the correct attachment point for the line to the oil cooler is directly above, and offset to the left of, the oil pressure screen housing? I think this is where the oil cooler bypass spring and plunger would go if I didn't have a Vernatherm.

My oil temps take quite a while to reach 100 F, and after an hour of landing practice only get to 160 F. This was only a few days ago in Phoenix when the OAT was 75+ F.

I verified that the Vernatherm opens and closes at the correct temperatures, roughly, when I did my oil change a week ago.

Here is part of Figure 7-4 in an O-320 Operator's Manual that show optional oil cooler connections.



Thanks for any help and advice.

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Brian Cabebe
N39JP

Hi Brian , I too have the 0-320,no vernatherm, I block off the cooler in the winter most generally. Summer time temps will reach 180 and Somtimes a little better than that, you won't have to worry about an over heat on the ramp leaving an event........Dan

Brian,
It's been awhile since I've thought about the exact location of those cooler lines/ fittings on the accessory housing. I'll take a look on Wednesday when I'm at the airport, if someone else hasn't already answered your question by then. My Lycoming manual is at the hangar now also.
Just a quick thought/question - have you checked the accuracy of your oil temperature gauge? At 75 deg. ambient temperatures, it would seem that your engine & oil would probably come up to temperature in a reasonable period of time, even if you had continuous flow through the cooler, but maybe I'm wrong.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

That's where I connected mine Brian - I think you are golden. Might wanna take a heat gun to the engine after a flight - my oil temp gauge currently reads about 10 degrees on the cool side.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

John and Fraser,

Testing the oil temp gauge, and sender, was going to be my next test.

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Brian Cabebe
N39JP

I may just not be paying enough attention. During today's flight to another airport for lunch, the oil temp got up to 180 F and stayed there. It was only as I reduced power to descend into the pattern that the oil temp started coming down.

My guess is that if I just stay in the pattern, I'm not running the engine hard enough to get the oil temp up to where the Vernatherm closes all the way, i.e. 180 F.

So, for now I'm not going to change anything. I'll just keep monitoring it and get used to what the oil temp is during different kind of flight ops.

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Brian Cabebe
N39JP

I believe the Lycomings like the 190-200 degree range for the oil temp. The closer to 200 degrees to ensure eliminating any "moisture" in the case . (EAA Web site) I run mine as close to 200 as I can using my inline damper control valve to the oil cooler . Some folks use duct tape over the cooler , but I prefer a cockpit control to adjust the air flow to the cooler .

RB

Same here Brian, at operating Rpm I can get some temp in the oil, into the pattern it slowly cools most of the time down to about 140Deg, cool on the ground don't bother me, like Rich says I do like to see 180deg plus at cruise. I built a Butterfly door to use on my cooler Rich to block off the cold on the cooler during cold weather, just got busy with other things and haven't installed it yet. This is quite possibility the best answer for oil temp to keep it in check as far as oil temp goes. Properly Baffled or installed plenum on the Thorp and the temps will run on the cool side this seems to be the norm....Dan

My plenum (modeled after Dan's work of art) is so effective that in the cooler days here in San Diego I have to fully close the damper valve to the oil cooler to get the oil temp. up . During the Summer it is wide open . Much easier to control the oil temp from the cockpit with a push pull cable than to have to use cardboard and duct tape ! BATA BING, BATA BOOM !

RB >:D