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Legacy R-12 Overheating Solution

RFSchaller

Well Known Member
I live in Phoenix. My 12 was licensed in 2012, and it’s pretty much the original design with D180 avionics. In summer I frequently get CHT and Oil temperature alarms during climb out, and sometimes I just can’t fly when it gets above 90F..

A few weeks ago I made some modifications suggested by my friend, Adam, at Flying Cacti flight school. I trimmed 3 1/2 inches from the lower cowl aft edge in the area of the cooling air outflow, installed two small deflectors just forward of the the edge on the outside to create a low pressure area at the air discharge and wrapped my muffler in a thin layer of exhaust insulation. Since then I have been flying in 98F temps and not picked up alarms although I still get into the caution range sometimes on climb out.

As an aside, Adam showed me the 12is his school is using, and he told me the relocation of the oil cooler and radiator have eliminated the overheat issue in the 12is.
 
I would caution against using a woven fiberglass cloth for wrapping the muffler. I used high-temp wrap on the right front exhaust tube with the thought of shielding the oil line that passes through the loop. The fiberglass breaks down with heat and vibration over time and sheds glass fibers everywhere inside the cowling including on the air filters. It would be bad if abrasive fiberglass found its way into the intake manifolds…
 
What, exactly, are you using for exhaust insulation?

Pictures and dimensions of 2 small deflectors, as well as aprox angle from existing surface?

How much additional drag, and or loss in airspeed noted?
 
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I’ll be out at the hangar Wednesday and get some pics. The muffler insulation I used was a sheet of fiberglass with adhesive on one side and shiny aluminum (?) on the other from Auto Zone.
 
An old fix for the legacy 12 was to just move the oil cooler about an inch forward to give clearance from the exhaust. Easy to do during construction. After built I suppose you could cut oil cooler mount and overlap sides and add glass strips to anchor and just paint inside black. Worked great on my 12 with never any problem with high temperatures.
 
I haven’t had much luck posting photos, but here are two of the finished mod and two of one the removed sections.

V <a data-flickr-embed="true" href="https://www.flickr.com/photos/193976359@N06" title=""><img src="https://live.staticflickr.com/65535/51479735802_c13016e839_z.jpg" width="640" height="480" alt=""></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>
 
You can use the "paper clip" icon for attachments, when you post, to load your photograph .jpeg files so that they show up in your post.
 
I replaced the exhaust system in my Classic 12. It improved the oil overheating problem significantly. This was a hot summer and I never had a yellow indicator for oil temp. Last year before the change I always had a yellow indicator shortly after takeoff n warm weather.

And as a bonus I now have zero carbon monoxide indications. So the exhaust leaks in the old system are gone.
 
I can’t win! No insulation and the engine overheats. Insulate and it accelerates exhaust failure.

I had an exhaust line break off a Continental O-200A on my first home built. I ended up with some charred wood at the edge of my firewall. That plane was always an adventure.
 
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