Jeff,
I doubt an air lock is/was the problem as it was oriented with the inlet/outlet on the side. If there was an air lock, I would think that at least part of the other end tank would get warm (which it doesn't). Good suggestion though.
This single cooler is almost twice the size as one of your coolers. So, it should be up to the task at hand. This is assuming that it is working as designed.
Mark
On Mon, Dec 14, 2009 at 11:20 AM, Jeff Whaley <jwhaley@datacast.com> wrote:
Hey Mark, I guess the only other logical reason would be an air-lock caused by orientation … but if you’ve got two exactly the same, that is highly unlikely.
Incidentally, I have two, 6.25”x11”2.75” oil coolers in series – I’m over-cooled with 2 but found 1 wasn’t enough.
JWW
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Monday, December 14, 2009 12:00 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Oil Cooling
Well guys, here is a new one... at least for me.
I've never been able to get my 20B oil temps quite low enough for comfort. I chaulked most of it up to the high Texas temps and an engine that produces gobs of horsepower (just kidding on the "gobs of horsepower" part). I'm running a 10" x 11" x 2 3/4" Fluidyne dual-pass oil/air cooler and a large (and heavy) Fluidyne oil/water exchanger. Water temps were fine but the oil temps would reach 240*-245* on climb, and just barely down to 200* in cruise. I tried different plumbing arrangements, added a cowl flap (which helped some), etc. Still, the temps didn't want to come down. Well, yesterday I ran the engine with the cowl off (doing some fuel pressure monitoring/adjusting), and I had just finished getting things up to operating temperature, verified that fuel pressure was good, and then shut it down. I just happened to touch the end tank on the Fluidyne oil/air exchanger and to my surprise, IT WAS STONE COLD! I touched the other end (inlet/outlet) and it was HOT! I thought this was odd. The only thing that I could figure is that the dual-pass oil cooler was defective. Since the cooler has no thermostat, I can only conclude that the internal tank separator, which is how they make a single-pass cooler into a dual-pass cooler, was allowing the oil to bypass the core and go directly from the inlet to the outlet. Well, no wonder I can't get the oil temps to come down!!!
I replaced the cooler with another unit I had on hand, ran the engine, and low and behold, both end tanks come up to temp together. I did a couple of ground runs and themps look encouraging. But unfortunately, it was too late to do a test flight yesterday. I'm sure the new cooler will make a big improvement. I'm hoping it will be enough to permit me to remove the oil/water exchanger.
Moral of the story... DON'T TAKE ANYTHING FOR GRANTED! TRUST BUT VERIFY!!!
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