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Low oil temps on 912ULS
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lgold(at)quantum-associat
Guest

Posted: Thu May 28, 2009 2:38 pm Post subject: Low oil temps on 912ULS

I fly a Zenith CH701 with a 912 ULS engine and my oil temps are running low.

Rotax says the operating temps should be between 190 and 230-degrees F. My

normal temps with 60-degree outside air run about 130-degrees at about

4800-RPM. I only get in the "normal" range when running near full RPM, about

5250 with my prop setting. I mostly use 91 octane mogas and CPS's

semi-synthetic AV-9 motor oil (which is supposed to be designed especially

for the 912).

Should I be concerned that the oil temps run below the normal range?

Les

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Thu May 28, 2009 4:12 pm Post subject: Re: Low oil temps on 912ULS

Hi Les,



It would be better if your CHT's ran a little higher. First I would set my prop to achieve 5500 rpm. You need to get the temps up so you can burn impurities off the oil and out of the system. The oil temp must be low, too. It is usually around the CHT temp mark depending on how you set the oil and coolant coolers up. You will have a better performing airplane in all aspects and save a little fuel if you bump up your rpm. About 1.5 degrees flatter pitch if you are running 5200-5250 WOT straight and level. This will also help with temps and you will develop more HP at a given rpm , plus you will get better all around flight characteristics. Your engine was designed to run between 4800-5200 rpm with the prop set to achieve 5500 engine rpm WOT.  5000 rpm is peak torque. After 5000 rpm torque starts to drop as HP continues to increase. 60 degrees is a cool day. If you can't bring the temps up then place a piece of 2" wide aluminum tape across the coolant radiator. This is an accepted practice by Rotax.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

m.tucciarone(at)hotmail.c
Guest

Posted: Thu May 28, 2009 4:15 pm Post subject: Low oil temps on 912ULS

I had the same problem with my 912s so I bought an external oil thermostat

from Lockwood. The oil should be over 190 so that it works correctly in your

engine. I have used the thermostat for about 3 years now without any

trouble. My oil temp stays around 195.



Matt 

--

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri May 29, 2009 6:58 am Post subject: Re: Low oil temps on 912ULS

Hi Matt,



Actually the temp needs to touch and exceed 212F for some time after

each flight. Usually on the ground after engine off.  The reason is that

water is a product of combustion of gasoline and if left in the oil will

hasten corrosion.  It needs to boil out.  Remember the boiling point of

water at the normal operation oil pressure is much higher than the safe

temp of the rotax alloy in the heads, so the boiling usually, occurs when 

the engine stops.



At 4 atm (60 psi) the boiling point of pure water is about 300C!

_________________
Ira N224XS

Goodone

Joined: 13 Sep 2008
Posts: 49

Posted: Fri May 29, 2009 7:00 am Post subject: Re: Low oil temps on 912ULS

My engine is a 912UL on a Skyranger and the oil temp in it also runs cool. I normally cover my oil radiator with aluminum tape and only remove it when the temperatures here in Maryland get really hot in the summer. During the winter I add a layer of insulation to the tape.

grahamsingleton(at)btinte
Guest

Posted: Fri May 29, 2009 12:10 pm Post subject: Low oil temps on 912ULS

rampil wrote:

 	  Quote: 	
		   Remember the boiling point of

 water at the normal operation oil pressure is much higher than the safe

 temp of the rotax alloy in the heads, so the boiling usually, occurs when 

 the engine stops.



 At 4 atm (60 psi) the boiling point of pure water is about 300C!



 --------

 Ira N224XS

Ira
	


I suspect you taught a lot of us something we had not thought through. 

Very good point.

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Fri May 29, 2009 1:49 pm Post subject: Re: Low oil temps on 912ULS

 	  grahamsingleton(at)btinte wrote: 	
		  rampil wrote:

 	  Quote: 	
		   Remember the boiling point of

 water at the normal operation oil pressure is much higher than the safe

 temp of the rotax alloy in the heads, so the boiling usually, occurs when 

 the engine stops.



 At 4 atm (60 psi) the boiling point of pure water is about 300C!



 --------

 Ira N224XS

Ira

	


I suspect you taught a lot of us something we had not thought through. 

Very good point. 	




Well remember water evaporates readily at lower temperatures than the boiling point. You don't have to boil it to "burn" it off. 



You pretty much only have to get the engine and oil hot enough to actually get it all evaporated before it gets too cold again to do so. Whether that's 212F, tho, I dunno. I look at the oil cap after the engine cools down, there's usually a little condensation on it if I didn't run the engine long enough to get it hot enough to burn off all the moisture.



As for the oil temp, I too have an oil thermostat installed on mine and it helps keep the temps up quite a bit. There are times in the winter tho where even that won't allow it to get to 180+. I"ve landed and put it away a few times in the very cold weather because I still couldn't get the oil temps over 160 or something like that without just really running the motor too hard.



LS

_________________
LS
Titan II SS

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Fri May 29, 2009 2:29 pm Post subject: Low oil temps on 912ULS

Sound to me like a set of Lowell's shutters would be right up your alley.

Open then in the climb and close them to cruise in warmer weather.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Fri May 29, 2009 4:24 pm Post subject: Low oil temps on 912ULS

Remember your lubrication system isn't sealed and under pressure like the

cooling system.  



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

m.tucciarone(at)hotmail.c
Guest

Posted: Fri May 29, 2009 6:28 pm Post subject: Low oil temps on 912ULS

I have never heard that. I was told that 190 would burn out the water in the

engine that would condensate in it. And it would make sense that 190 number

was correct because my thermostat keeps the oil between 190 and 200. 



Again I have never heard that it has to be about 212.



--

rholder(at)avnet.co.uk
Guest

Posted: Sat May 30, 2009 12:40 am Post subject: Low oil temps on 912ULS

 	  Quote: 	
		   Well remember water evaporates readily at lower

 temperatures than the boiling point. You don't have to

 boil it to "burn" it off.

 

 You pretty much only have to get the engine and oil hot

 enough to actually get it all evaporated before it gets

 too cold again to do so. Whether that's 212F, tho, I

 dunno. I look at the oil cap after the engine cools

 down, there's usually a little condensation on it if I

 didn't run the engine long enough to get it hot enough

 to burn off all the moisture.

 

 As for the oil temp, I too have an oil thermostat

 installed on mine and it helps keep the temps up quite

 a bit. There are times in the winter tho where even

 that won't allow it to get to 180+. I"ve landed and put

 it away a few times in the very cold weather because I

 still couldn't get the oil temps over 160 or something

 like that without just really running the motor too 

 hard.


	




One thing to remember, and no-one ever mentions it is :



The oil temperature is measured at the oil pump on the way

INTO the engine. AFTER the oil has been through the oil

cooler.



That means that a temperature of 180 shown on the gauge

may well mean that the oil in the oil tank is 212 or more.

So it is not necessary to have the gauge show 212 to be

sure the oil has reached 212 !



Richard Holder

grahamsingleton(at)btinte
Guest

Posted: Sat May 30, 2009 1:08 am Post subject: Low oil temps on 912ULS

lucien wrote:

 	  Quote: 	
		   

 grahamsingleton(at)btinte wrote:

   

> rampil wrote:

>

>     

>>  Remember the boiling point of

>>  water at the normal operation oil pressure is much higher than the safe

>>  temp of the rotax alloy in the heads, so the boiling usually, occurs when 

>>  the engine stops.

>>

>>  At 4 atm (60 psi) the boiling point of pure water is about 300C!

>>

>>  --------

>>  Ira N224XS

>> Ira

>>

>>       

> I suspect you taught a lot of us something we had not thought through. 

> Very good point.

>     

 Well remember water evaporates readily at lower temperatures than the boiling point. You don't have to boil it to "burn" it off. 



 You pretty much only have to get the engine and oil hot enough to actually get it all evaporated before it gets too cold 



 LS

I forgot also that the oil is only at 4 atm inside the engine, when it 
	


vents into the tank its down to 1 atm.

Graham

pwmac(at)sisna.com
Guest

Posted: Sat May 30, 2009 6:22 am Post subject: Low oil temps on 912ULS

Of course airplanes don't fly at sea level. And since the oil system is basicaly open to the atmosphere (or slightly below) the the boling point of any water would be less than 212F. That is why the cooks have to adjust the recipies for altitude.!90F is a reasonable level for oil temp to vaporize any water condensate. Guys who fly in CO will get rid of water at even lower temps depending on the flight altitude.

  Paul



 

 On 5/30/09, R Holder <rholder(at)avnet.co.uk (rholder(at)avnet.co.uk)> wrote: [quote]--> RotaxEngines-List message posted by: R Holder <rholder(at)avnet.co.uk (rholder(at)avnet.co.uk)>

 

  	  Quote: 	
		  Well remember water evaporates readily at lower

temperatures than the boiling point. You don't have to

 boil it to "burn" it off.



You pretty much only have to get the engine and oil hot

enough to actually get it all evaporated before it gets

too cold again to do so. Whether that's 212F, tho, I

 dunno. I look at the oil cap after the engine cools

down, there's usually a little condensation on it if I

didn't run the engine long enough to get it hot enough

to burn off all the moisture.



As for the oil temp, I too have an oil thermostat

 installed on mine and it helps keep the temps up quite

a bit. There are times in the winter tho where even

that won't allow it to get to 180+. I"ve landed and put

it away a few times in the very cold weather because I

 still couldn't get the oil temps over 160 or something

like that without just really running the motor too hard.

	




One thing to remember, and no-one ever mentions it is :



The oil temperature is measured at the oil pump on the way

 INTO the engine. AFTER the oil has been through the oil

cooler.



That means that a temperature of 180 shown on the gauge

may well mean that the oil in the oil tank is 212 or more.

So it is not necessary to have the gauge show 212 to be

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rampil

Joined: 04 May 2007
Posts: 870

Posted: Sat May 30, 2009 6:55 am Post subject: Re: Low oil temps on 912ULS

Yes, most water leaves the oil from reservoir, but also from the crankcase

which is where the rust forms from condensation.



Try a little experiment:

Leave your master electrics on for a few minutes after engine

shutdown (assuming a cowl!).  Watch the oil temp rise.



Also, keep in mind that the rate of vaporization is (for a particular species

like water) proportional to the difference between the vapor pressure

and the ambient pressure. Since the VP goes up exponentially with

temp, a small increase in temp makes a big difference in rate of water

evaporation,



Ira

_________________
Ira N224XS

gfmjr_20(at)hotmail.com
Guest

Posted: Sat May 30, 2009 11:29 am Post subject: Low oil temps on 912ULS

You might try installing an oil thermostat--available from Lockwood. i have one on my Rotax 912uls.



George May

601XL 912uls

[quote] From: noelloveys(at)yahoo.ca

 To: rotaxengines-list(at)matronics.com

 Subject: RE: Low oil temps on 912ULS

 Date: Fri C 29 May 2009 22:28:01 -0230

 

 --> RotaxEngines-List message posted by: "Noel" <noelloveys(at)yahoo.ca>

 

 Sound to me like a set of Lowell's shutters would be right up your alley.

 Open then in the climb and close them to cruise in warmer weather.

 

 Noel

 

 --

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sat May 30, 2009 12:52 pm Post subject: Re: Low oil temps on 912ULS

My temps right now in my Flight Design CT is 190-200 oil temp and 195-200 CHT. This is with a 73F-75F OAT.

The oil thermostat is open at 180F and that's it. They are made by 

Perma-Cool. They do not have anything that opens higher. With the CT's I don't see any heating up to operating temp any faster with the thermostat than the ones without the thermostat and the regular temps aren't any better after warm up. If we want higher temps when it gets cool most guys use the 2" aluminum tape across the radiator. Setting the prop to achieve higher rpms (5500 WOT) will also get you more HP which will increase the temps some.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun May 31, 2009 2:16 am Post subject: Re: Low oil temps on 912ULS

Roger,



in Buffalo during winter months, the Perma-Cool oil thermostat DOES speed up the oil warming process and with the help of tape over the oil cooler, it does keep the temps up to a minimum of 170F, even during low power descents in frigid temperatures. In our part of the world, I consider the oil thermostat essential equipment for 912 engines. Before installing the oil thermostat, complete coverage of the oil cooler did not keep the oil above 170F during low power descents.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun May 31, 2009 5:54 am Post subject: Re: Low oil temps on 912ULS

Hi Thom,



Yeah your right, I forgot that some live in a deep freeze in the winter. I was thinking a little more about the temps this time of year when he was talking 60F. Yes it would help for those of you that live in those sub arctic temps during the winter. I kind of forget how cold it really gets back in some places like Minn and upper NY during the mid winters. You guys will have to excuse me because I live in a foreign country, Tucson, Az. and don't see much of that type of winter.    

They also make a water thermostat that is set for 180F, too. The flight Design's come with an oil and water thermostat from the factory now. Makes the area around these things a PITA to work on or around.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun May 31, 2009 6:00 am Post subject: Re: Low oil temps on 912ULS

Roger,



One of my good flying buddies here is from Tucson originally but he has acclimated to the "sub arctic" as you call it. You should visit this part of the world during summer. On the leeward side of the Great Lakes, the temps get up to 90 on average about 2 days per year. This morning the temp was 48F with an expected high of mid-60s. 



do not archive

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

icrashrc

Joined: 16 Mar 2006
Posts: 247
Location: Mishawaka, In

Posted: Sun May 31, 2009 11:19 pm Post subject: Re: Low oil temps on 912ULS

Roger,



Who's carrying the water thermostat?  I'm guessing there's some plumbing changes involved. Do you know where we could see some installation pictures? Thanks,



Scott



 	  Roger Lee wrote: 	
		  They also make a water thermostat that is set for 180F, too. The flight Design's come with an oil and water thermostat from the factory now. Makes the area around these things a PITA to work on or around.

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