REFLECTOR: Rear oil cooler

[Dave Black]

Andy,


> Is the second oil cooler in the rear always needed on the IO-540  
> installations? If so what is the proper pluming to make two coolers  
> work? Do you plum them in series with the front cooler plumed first  
> to give you enough heat for winter or what? My IO-540 E1A5 from an  
> Aero Commander was only using one oil cooler.


The official nose-mounted oil cooler location was chosen to allow one  
cooler to serve both to cool the engine and to heat the cabin.  
However that location turns out to be fairly ineffective as a cabin  
heater AND less than ideal for cooling the engine. So it is best if  
you can use two oil coolers. The coolers should be connected in  
PARALLEL, with a selector valve between them. For winter you send the  
hot oil to the nose, while for summer you can send it through engine  
compartment cooler.

If I was designing my oil system now, I'd move the nose-mounted oil  
cooler to the cabin interior instead. There you could install a 12v  
blower to circulate the warm air around the cabin. This would save on  
oil line, and provide much more effective cabin heating.

One important reason the interior-mounted cooler works so much better  
at warming the cabin -- the air can recirculate. Consequently you can  
make the cabin as warm as you want. All you have to do is turn the  
heater on full and close off the fresh air vents. With the nose- 
mounted cooler, you get only one shot at warming the outdoor air  
before it enters the cabin. I think you'd be lucky to see the nose  
cooler increase the cabin temperature 30°f. That works just fine at  
sea level in Florida, but not so good at 12,000ft in Minnesota.


dave black
Shortwing RG