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View Full Version : Today I Learned Something Interesting About Air Colling

fiveboy
02-25-2009, 01:42 PM
My motor has two cooling fans. The motor instruction manual makes it clear the engine needs air flow.

Yesterday I replaced a rubber receiver that the air filter seats into and which sits atop the cylinder. A crack in the rubber was allowing air in and my EGT was high. Replaced, tested.... 100F lower. Yeah!

Go to fly this morning and I get a warning light! WTF how can this be!??? Rechecked retightened etc.

Come to find out that by positioning my motor so it had a brisk wind coming at it from the rear (the wind is 97 deg F) I was defeating the fan! I turned the machine so the wind was coming toward the engine (as it would in flight) and bingo back to normal!

Interesting lesson not found in a book.
scottessex
02-25-2009, 02:10 PM
Try flying with a foot on either rudder pedal and see if you can cool off one side or the other in a sideslip.

Make sure that the fan guards are tight, they have been known to go through the prop and do ugly things.
All_In
02-25-2009, 03:04 PM
Thanks Rob, one more great tip to help us all diagnose future problems.
fiveboy
02-25-2009, 06:00 PM
Try flying with a foot on either rudder pedal and see if you can cool off one side or the other in a sideslip.

Make sure that the fan guards are tight, they have been known to go through the prop and do ugly things.

Scott I think you are being serious so I have to ask... what would this prove?
scottessex
02-26-2009, 02:25 AM
Well if you lost a fanbelt, you might be able to keep the one side cool and limp home, or at least buy a little time picking a landing spot instead of seizing the engine. Will it work? I don't know.
fiveboy
02-26-2009, 11:10 AM
Today I went to fly and one of my CHT was through the roof on start up... and I was facing the right way. Back to the barn! In that after the engine was cooled I was getting readings of 65 65 65 360..... im thinking I might have a bad sender to my EIS. I ordered 4 new ones and will just replace them all and hope for the best. When I asked the factory rep which was the #1 cylinder he said it depends on which sender they hooked where.... so now I need to test using a match to see which one reacts where.

As they say here in the south....OY!