The International Cessna^® 170 Association

I was reading with interest another post about the finned oil filter devices. This is a different type of airplane but similar to the 170. My buddy’s 140A with an O-200 stc’d engine was running high oil temps. Close to read line, he was playing with trying to get the upper baffling as tight and as closed up as he could. Nothing seemed to make much difference. Then he had me fit a new nose bowl to his cowling because the old one was beat up. During the process I made a much tighter fit around his carburetor air filter, which would keep air from getting into the lower cowl area. I only did it for neatness and appearance. He was much surprised when the next time he flew the airplane he discovered that his oil temps were as much as 15 degrees cooler and no where read line. Now during the cooler parts of the year he has to run the block off plates in the lower cowl.

Jim

Inside the lower cowl is (supposed to be) a low-pressure area, created by the venturi effect of the opening in front of the firewall- the air rushing by under the plane draws the cooling air down thru the engine from the nosebowl opening. Air leaks into this low-pressure area hurts that airflow, and so temps go up. Something for us to look at. I've often wondered why some Skywagon owners do a mod where you cut in little louvers into the sides of the lower cowl? Seems like this would mess up the low-pressure area & hurt airflow.

Eric

Yep George was pointing that out in the other thread. My response was based on the assumption that all these type of things were inspected and fixed first. Probably should have clarified that.