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Buckaroo

Another oil temp question?

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Today in Montana it was almost 100 degrees. Until today I’ve never flown the CTSW in anything over the 80’s. I was a little concerned watching the temp gauge bouncing in the 225 range almost in the yellow. To prevent a nail biter on another flight can someone enlighten me as to what would be normal and safe if she were to go into the yellow? The yellow arc is pretty large but in degrees what would be the find an airport to land numbers?

 Thanks everyone!👌

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Some of our CTSWs have oil cooling issues.  With 100* ambient temps I will be flirting with the red-line (265*) even before take-off if I have to wait.

Climbing in the yellow is routine for me, I can get my cruise down to 235* as long as I climb to where ambient is below 70*.

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4 hours ago, Ed Cesnalis said:

Some of our CTSWs have oil cooling issues.  With 100* ambient temps I will be flirting with the red-line (265*) even before take-off if I have to wait.

Climbing in the yellow is routine for me, I can get my cruise down to 235* as long as I climb to where ambient is below 70*.

Thanks Ed! Between the fuel psi reading zero off and on and the heat climbing well into the zero it’s comforting to hear information given like this!👌👍

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It isn’t 265. It is 248 if you using a 50/50 coolant. The 265 is too close to boiling and vapor production. You need to make your max 250 and no more. This has been a Rotax bulletin for years. There are several things that can affect engine temps. It can be type of coolant (Evans vs 50/50), prop pitch (you may need to reduce pitch some), radiator alignment and open face exposure(make sure the radiator is centered and you may need to cut out a little more cowling in front of the radiator), I cut mine and it dropped temps another 10f. It doesn’t take much.  Climbing temps in the yellow is normal during summer months. I wouldn’t lose any sleep p to 245. Angle of climb combined with air speed can add to increased or decreased temps. 

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The yellow temp range from 230 and let’s say 245 is nothing more than an attention alert that just means keep an eye on me and don’t let me get into the red. Climbing in the yellow is very normal this time of year.

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23 minutes ago, Roger Lee said:

It isn’t 265. It is 248 if you using a 50/50 coolant. The 265 is too close to boiling and vapor production. You need to make your max 250 and no more. This has been a Rotax bulletin for years....

This thread is about oil temps.  Even with my oil above 250 my coolant is in the green.

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I just moved my rad. up about 3/4 inch and also made a bracket that moves the rad.

more forward at the bottom which helps also, sits up straighter into the air flow.

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25 minutes ago, Roger Lee said:

. Angle of climb combined with air speed can add to increased or decreased temps. 

This has never worked for me, not even 1 degree.  The best plan for me is to climb to altitude where it is below 70*F as quickly as possible.

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1 hour ago, Roger Lee said:

It isn’t 265. It is 248 if you using a 50/50 coolant. The 265 is too close to boiling and vapor production. You need to make your max 250 and no more. This has been a Rotax bulletin for years. There are several things that can affect engine temps. It can be type of coolant (Evans vs 50/50), prop pitch (you may need to reduce pitch some), radiator alignment and open face exposure(make sure the radiator is centered and you may need to cut out a little more cowling in front of the radiator), I cut mine and it dropped temps another 10f. It doesn’t take much.  Climbing temps in the yellow is normal during summer months. I wouldn’t lose any sleep p to 245. Angle of climb combined with air speed can add to increased or decreased temps. 

According to Rotax's operating instructions max oil temp is 285°, with the top of the normal being 245°.

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1 hour ago, Roger Lee said:

The yellow temp range from 230 and let’s say 245 is nothing more than an attention alert that just means keep an eye on me and don’t let me get into the red. Climbing in the yellow is very normal this time of year.

So if ones on a cross country and say temps are reaching the 250 mark what cooling actions

should you take. I hear running slower rpm can actually lean the motor which makes it hotter! Descending makes warmer air etc.

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Plenty of data to support all these assertions in the archives. A wealth of information.

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2 hours ago, Buckaroo said:

So if ones on a cross country and say temps are reaching the 250 mark what cooling actions

should you take. I hear running slower rpm can actually lean the motor which makes it hotter! Descending makes warmer air etc.

This is generally only an issue in climb, you should not have a problem in cruise even in high outside temps.

My CT runs pretty hot, and I can keep my temps below 245 even in summer here in Georgia.  Once I’m cruising it’s usually 225 or so in summer, maybe 230 if it’s super hot and/or I’m at low altitude.

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2 hours ago, WmInce said:

Plenty of data to support all these assertions in the archives. A wealth of information.

Yes I know the archives are cool but newbees do better real time! Seldom do I post an amateur question and not find spin off questions that even Tom and Roger ending up debating. 

Its all good!

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8 hours ago, Ed Cesnalis said:

This thread is about oil temps.  Even with my oil above 250 my coolant is in the green.

I am talking about oil temp.

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7 hours ago, Tom Baker said:

According to Rotax's operating instructions max oil temp is 285°, with the top of the normal being 245°.

Which engine? For those that don’t know the manual is written for three engines and you need to make sure which you’re looking at as far as specs. The 912UL 80 hp, 912 ULS 100 hp or the 914 115 hp. Now we also have manuals for the 912iS and 915.

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1 hour ago, Roger Lee said:

Which engine? For those that don’t know the manual is written for three engines and you need to make sure which you’re looking at as far as specs. The 912UL 80 hp, 912 ULS 100 hp or the 914 115 hp. Now we also have manuals for the 912iS and 915.

OK, so I picked up the wrong engine from the operators manual. The max oil temp for the 912 ULS is 266°F.

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266 if you used Evans coolant which we don’t so the SB that came out years ago says 248 if you use 50/50 coolant because 266 is too close to the vapor production point of 275 for 50/50.

So 250 should be your max.

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So back to my question that no one answered if you cruising cross country and hitting 250 what actions could one try to change the scenario? Would backing out of 5500 rpm to say 5200 help or a short climb to cooler temps or a decent keeping rpm constant at 5500 or dumping rpm??

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1 hour ago, Buckaroo said:

So back to my question that no one answered if you cruising cross country and hitting 250 what actions could one try to change the scenario? Would backing out of 5500 rpm to say 5200 help or a short climb to cooler temps or a decent keeping rpm constant at 5500 or dumping rpm??

If I were hitting 250° in cruise I would land and investigate.  It shouldn't happen. 

In my experience, the engine runs significantly hotter at 5400-5500rpm, so if you are cruising in that rpm range going down to 5200rpm would probably buy you 5-7° cooler temps.

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2 hours ago, Roger Lee said:

266 if you used Evans coolant which we don’t so the SB that came out years ago says 248 if you use 50/50 coolant because 266 is too close to the vapor production point of 275 for 50/50.

So 250 should be your max.

Roger, the current Rotax Operating Instructions state 266°F with no notation about which coolant you are using. I did a quick look and didn't find the SB you were referring to, could you please post a link?

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9 hours ago, Roger Lee said:

266 if you used Evans coolant which we don’t so the SB that came out years ago says 248 if you use 50/50 coolant because 266 is too close to the vapor production point of 275 for 50/50.

So 250 should be your max.

Why would oil max temp depend on coolant type?

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30 minutes ago, Roger Lee said:

Because Evans carries a 20-30F temp penalty and when the engine runs hotter so does the oil.

I don't follow the logic.  If it does run hotter it is then permitted?  

 

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Evans boiling point is 375F. 50/50 is around 270-275F.  Evans won’t vaporize at 270F, but 50/50 will so Rotax lowered the max temp of 266F to 248F to prevent vaporization and engine damage. If you are at 235-240F on a climb out the Evans temp penalty will take you over max. Rotax does not want Evans used any more.

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