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912S oil temp

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lazflyn

Joined: 13 Nov 2007
Posts: 3
Location: Utah, USA

Posted: Sun Jan 27, 2008 4:40 pm Post subject: 912S oil temp

Hello,



I just bought a Series 5.  I am experiencing oil temps that are too high.  This happens at high power settings (above 5000 rpm) in level cruise.  It's winter time and that really concerns me.  What can be done to help cool the oil better, especially when summer rolls around and it is really needing to be cooled.



The oil cooler is mounted below the front of the engine, with a dedicated scoop for it.  Is there not enough air exiting the rear of the cowl?  Not enough flow through the radiator and side exits of the firewall?  Air bubbles in my oil?



Please help me understand the possibilities, I am new to aircraft ownership.  The builder said I should mount the oil cooler on top of the radiator to help.  Do you think that would help?



Thanks in advance.

pulsair(at)mindspring.com
Guest

Posted: Sun Jan 27, 2008 8:11 pm Post subject: 912S oil temp

Inspect the oil line from the oil cooler to the oil pump. It is very short 

and does an immediate bend. If the bend is a bit much it cuts the oil supply 

some and gives you high pressure readings. It could also affect oil temps. 

At least worth a look. Jeff Classic IV CMH

---

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Sun Jan 27, 2008 8:38 pm Post subject: 912S oil temp

At 04:40 PM 1/27/2008, you wrote:

 	  Quote: 	
		  Please help me understand the possibilities, I am new to aircraft 

ownership.  The builder said I should mount the oil cooler on top of 

the radiator to help.  Do you think that would help?


	


Some assistance may be found in the archives: 

http://www.matronics.com/searching/ws_script_short.cgi. Select 

"Kitfox" under "Select Archive" and search for "high oil temp" and 

you'll get a bunch of hits. This has been a common problem with 

Series 5's. (One of my flying compatriots replaced his stock 5 oil 

cooler with one 50% bigger and ducted from the inlet to the cooler. 

His heat problems diminished, but the darn thing keeps falling off! 

Lousy bracket designs.)

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

KFN102LG(at)aol.com
Guest

Posted: Mon Jan 28, 2008 8:49 am Post subject: 912S oil temp

What's too high?   Have you checked the gauge for accuracy?   Hoses not soft and collapsing from suction?   

 

 Larry

**************

Start the year off right.  Easy ways to stay in shape.

     http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489  [quote][b]

randy(at)romeolima.com
Guest

Posted: Mon Jan 28, 2008 9:36 am Post subject: 912S oil temp

As a lurker and someone considering starting a Super Sport,  does the standard 912S package not have thermostats for both the oil and coolant  systems?

  

 Randy Lervold

 2-time RV builder, Kitfox maybe

  

 [quote]   ---

lazflyn

Joined: 13 Nov 2007
Posts: 3
Location: Utah, USA

Posted: Mon Jan 28, 2008 2:15 pm Post subject: Re: 912S oil temp

Wow!  Thanks for the quick response guys!



First off, to Mr. "Lurker" (aka. Randy) - Are you trying to hijack my thread?  Just kidding, but to answer your question:  The 912S that I have does NOT include an oil thermostat.  That is an upgrade you can purchase from Lockwood, I do believe.



Guys, I do have a couple of pics I think will help.  The first picture shows the additional scoop that directs airflow directly onto the oil cooler.  At least that's the theory anyway.  No provision was made to increase the size of the exit, so I don't know how much air is getting into that scoop.  But I could be up in the night though...  I'm pretty new to all this and haven't ever built a plane before.  



The second one clearly shows the routing of the oil lines.  I don't believe they are kinked (maybe slightly - right before the oil pump).  The radiator was mounted so that the in and out is on the bottom of the oil cooler.  This allowed for more room in the bend to the oil pump (I'm guessing).  



I haven't checked the tubing for softness.  I will when I get out to the hanger next.  I didn't think about that.



The temps I am seeing are all the way up to 260!(NOT sustained, it just headed up that way and I started my descent and reduced the power setting to cool it off).  That's with an OAT of 20°F!!!  Strange though, I was able to fly last Saturday with outside temps that were higher (probably around 35°F) and the oil stayed around 210.  My oil pressure at startup is maxed at 99 psi.  After warm-up it goes down to 35 or so.



Thanks for your help so far.



Mark

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Vic Baker

Joined: 11 Jan 2006
Posts: 71
Location: Carson City, Nevada

Posted: Mon Jan 28, 2008 3:01 pm Post subject: 912S oil temp

Good idea to provide a couple of pictures of the oil cooler install.  I 

would comment that the hose routing,  into the bottom of the cooler, could 

be the problem.  Trapped air.  Rotax install instructions advises against 

this.  I'd talk to Lockwood.

Vic Baker

S7 912S Warp 95%

Carson City, Nv

---

_________________
Vic Baker
Series 7
Carson City, Nevada

dcsfoto

Joined: 24 Aug 2006
Posts: 120

Posted: Mon Jan 28, 2008 3:44 pm Post subject: Re: 912S oil temp

the new oil cooler Kitfox uses looks much larger and is mounted against the front of the water radiator.



David Kitfox III and 7

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Mon Jan 28, 2008 4:34 pm Post subject: 912S oil temp

At 04:40 PM 1/27/2008, you wrote:

  	  Quote: 	
		  The oil cooler is mounted below the front of the engine, with a dedicated scoop for it.  Is there not enough air exiting the rear of the cowl?  Not enough flow through the radiator and side exits of the firewall?  Air bubbles in my oil? 	


         I finally looked at your pictures. (Dial-up connection, you know.) First I agree that the first impression is that it will be nearly impossible to bleed the oil cooler without some kind of air bleed screw on top. (Otherwise you'll have to remove the cooler and turn it over and bleed it manually. TOO MUCH WORK!

         Second, it's entirely possible that NO air is going through you oil cooler. You see, in order to get air to flow through it there must be a change in pressure from front to back. (Or back to front, if you want the air to go backwards! It works just the same.) Looking at the coolant radiator you can see where that pressure differential derives. The front face of the radiator is at static plus some fraction of the dynamic pressure provided by the three forward facing inlets. (Called the total pressure.) The back of the radiator is at the pressure of the bottom scoop, which facing aft should be at something near the static pressure alone and therefore a much lower pressure than the front of the radiator. Therefore air flows through the radiator, from high pressure to low. (This even works at rest because of prop wash.)

         Your oil radiator appears to have no air ducted to it, nor away from it. Both faces, therefore, are at the same pressure and it will only cool as a passive convection radiator, shedding heat to the air around it. (Like a radiator in a house.) Unfortunately your lower inlet may be doing next to nothing, because the interior of the cowl is already at high pressure due to the inlets above. Even if you were to duct the lower inlet to the oil cooler it might do nothing, because the back side of the cooler, being in front of the radiator, is at the cowl's high internal pressure. (It might cool a little bit, if the total pressure of the air at the lower inlet is higher than that at the inlets above, however it would be extremely inefficient, meaning low flow.)

         What to do? Probably nothing. Most 5's I've seen mount the oil cooler to the front of the radiator. This combination of air and oil cooling appears to be enough for the job. (I suggest it might help to somehow "seal" the edge of the oil cooler to the front face of the radiator, thus forcing the full pressure differential across the oil cooler / radiator combo.) Otherwise, if you want flow through your oil cooler you'll have to pass air through it. This is usually done by ducting in and out, high pressure to low, like the radiator. You might have success with just ducting in, (some put their oil coolers right up front, blocking an inlet, and thereby forcing a pressure differential,) but it will be strictly hit or miss. (The Lancair guys have had some success using a spare ASI as a dynamic pressure meter and a spare altimeter as a static pressure meter. They then instrument their cooling system incrementally in an attempt to optimize the pressure drop.)

         That's the short answer. By the way, nice job on the cowling.



 

 Guy Buchanan

 San Diego, CA

 K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.    [quote][b]

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

lazflyn

Joined: 13 Nov 2007
Posts: 3
Location: Utah, USA

Posted: Mon Jan 28, 2008 4:36 pm Post subject: Re: 912S oil temp

I have a new oil cooler that came with the purchase of the plane.  The previous owner/builder said that he was going to mount the new oil cooler in front of the coolant radiator.  He never said that he was having oil cooling problems (of course).  He said that he was going to move the radiator because the mounts crack when it is mounted up in front of the engine and that all the new Kitfoxes (series 7) mount the oil cooler in front of the coolant radiator.



Has anyone mounted their oil cooler on top (in front) of their radiator?  How have the temps been of the oil and coolant before and after the move of the oil cooler?  Could they post pictures of their installation (mounting method)?  I think I would like to try that if it would be successful.



Thanks,



Mark

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