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Oil Cooler By-pass

N

NunavutPA-12

FRIEND
67.8N,115.1W CYCO Canada
Has anyone in the experimental crowd installed a by-pass valve to divert oil around (rather than through) the oil cooler? Seems like it might help in cold conditions to be able to control the oil temperature from the cockpit. Maybe quicker warm-ups too.
 
Bill Rusk has a valve with control cable on his if I remember right, but I am into the red wine tonight so might be someone else.
DENNY
 
A Vernatherm does in fact cause the oil to bypass the cooler. A viscosity valve does nothing in that regard until the oil pressure hits about 100 psi., and then only the oil that's being "dumped" (a small %) is bypassing the cooler. If you were to bypass the cooler with a valve, I think you'd want to use a blending-type valve (in reverse) so there is no hard "off" position.

-- For faster warm-up I bring mine up to 12-1300 RPM, pull on carb. heat and then peak the mixture. This way I have warm air going through the sump and the mixture is correct so its not fouling plugs.
 
Last edited:
Well, here's my thoughts, for what they're worth:

The Vernatherm seems to be there more to protect the oil-cooler from the excessive pressure caused by cold oil. It's not precise enough to control the oil temperature. Covering the oil cooler with duct tape is a guessing game, and obviously can't be adjusted in-flight. A controllable shutter over the cooler gets mechanically complicated. But a valve with a by-pass line would allow precise oil-temperature control from the cockpit. I don't think it would hurt anything to have 100-percent by-pass for warm-up - after all, in very cold weather I've been covering 100-percent of the cooler with duct-tape.
 
My interpretation isn’t that the Vernatherm doesn’t work but rather the cooler works too well. Controlling airflow through the cooler solves the problem for lots of guys. Duct tape is the popular choice. Van’s and Dan’s have been selling adjustable cooler doors for years. They provide adjustability from the panel. My new plane has butterfly valves in the cooler outlet ducts. I wouldn’t want a flow valve in my oil lines but if it interests you? Go for it.
 
Consider the climate in which you operate and the potential for a congealed oil cooler. I like the idea that my coolers are flowing warm oil but with restricted cooling better than metering a small amount of oil through a cooler that's got excessive cooling potential. I'd be concerned about the cooler being congealed when I opened that valve and the ability for oil to free it up while in flight in sub-zero temps.
 
Van’s supplier for the shutter stopped making them, just before I decided to buy one, never fails. So there is an opportunity for some young entrepreneur.
 
stewartb said:
Consider the climate in which you operate and the potential for a congealed oil cooler. I like the idea that my coolers are flowing warm oil but with restricted cooling better than metering a small amount of oil through a cooler that's got excessive cooling potential. I'd be concerned about the cooler being congealed when I opened that valve and the ability for oil to free it up while in flight in sub-zero temps.
Click to expand...

Good point.
 
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