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Mechanics and Maintenance Shops

CHT in cold weather - C180
Author Last Post
There is very little variation in my CHTs between 70*F and sub-zero ambient temps. That's typical of each airplane I've owned. Oil temps vary greatly. I keep my oil cooler taped about 30% all summer and double that or more in winter. I have a cessna winter front kit and that made CHTs go up too high to be useful. I do have shroud baffles on the front cylinders to allow them to warm to where the others run. My CHT spreads are quite close for a carb'd 520. 
 
 
The engine was running rough which was as a result of carb ice.  When carb heat was used the engine cleared up.
Further investigation into the cooler temps was the EGT gauge was indicating peak at a much richer setting than peak.  Bottom line is that I should have leaned the engine to peak without referencing the EGT gauge then richen from there.  I was running the engine richer than what gauges indicated which is an explanation for cooler CHT's and Oil temp's.  Ran it yesterday but ambient air temp was much warmer than previous flight, however everything ran perfectly fine.  Thank you all for input!
 
 
Are you sure your CHT gauge is correct? It can be tested in boiling water. Some air taxi operators in Alaska do not use any winter covers and they have good luck with their engines even around Fairbanks where -30°F/-35°C is common.
 
Winter covers over the air intakes is all you should do in sub-zero temps but watch CHTs closely as ambient temps warm, say because of climbing into a temp inversion, you can easily overtemp the cylinders. That can damage cylinders worse than running CHTs too cool.
 
Taping off the oil cooler is a good idea. Be careful to not tape more than about half-way to start with until you know how its going to work. You probably have a non-congealing cooler already which should prevent the cooler from plugging off with cold oil but the cooler also needs some air flow to keep the oil from overheating.
 
What is requiring you to use carb heat?
 

If you over prime in very cold weather with a cold engine you can start an engine fire as gas pours out of the carb and / or cylinders. Trust me on this one.

 

From: mailer@mail2.clubexpress.com [mailto:mailer@mail2.clubexpress.com]
Sent: January-22-16 4:29 AM
To: Mechanics and Maintenance Shops
Subject: re: CHT in cold weather - C180 <<$141615648533$>>

 

Seems to me your oil temperature is more important. Have to burn off moisture out of the oil. Be careful near -25 many quit flying Pistons when outside air temps get that low. You can have problems with fuel at that temp.

CET

From iPad

 
Seems to me your oil temperature is more important. Have to burn off moisture out of the oil. Be careful near -25 many quit flying Pistons when outside air temps get that low. You can have problems with fuel at that temp.

CET

From iPad
 
HI,  I am wondering if my CHT are too low and if there is a way to increase CHT's.  We flew in ambient temperatures in -23º to -25ºC.
First flight (2.5 hours) no winter cover, however oil cooler was taped to increase oil temperature.  CHT hovered around 200º - 225ºF.  Carb heat was required to stay on almost 85% of the time.  Next day installed winter covers (ambient temp -23ºC).  CHT's increased slightly between 225º - 265ºF.  Carb heat was still required about 65% of the time.
Is this normal for Continental 0-470L in these temperatures?
 
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