Aux Oil coolers?

[207WF]

We used to use auxilliary oil coolers on VW powered dune buggies back in the day. I wonder if anyone has ever seen one on a 912? Maybe that would solve the high oil temperature problem on some CTs? WF

[Admin2]

Any high oil temps aren't an engine design issue or even a standard CT issue or we would all have them. You need to find the root cause. It could be a slow flow from a little garbage in the oil cooler. I would personally change the routing of the oil return line off the bottom of the engine. It's too short and makes too sharp a bend. Any slow oil flow will make the temps rise. Too course a prop pitch will do it or a reduced radius coolant hose.

[207WF]

All those ideas have been checked off, so I am looking for some new ones! WF

[Admin2]

Have you changed and lengthened the bottom engine oil hose that returns to the oil tank? Have you removed the oil cooler and flushed it? Anti freeze in use?

[Ed Cesnalis]

Have you changed and lengthened the bottom engine oil hose that returns to the oil tank? Have you removed the oil cooler and flushed it? Anti freeze in use?

 

I have done those things. I have never confirmed that my gauge reads correctly though.

 

 

 

[Mike]

In the UK we have a job to get them to 100 deg we have to tape up the cooler rad even in the summer

 

Mike

[FredG]

Do all aircraft using the 912 locate the oil cooler directly behind the coolant radiator? Seems like a poor way to exchange heat from the oil into the airstream.

[Jim Meade]

Depending on the plane the oil ans coolant may be separate ans in a completely different location.

 

What is your experience with these separate layouts as far as oil temperatures is concerned?

[Adam]

I have never seen a CT that doesn't have oil temp problems? (on climbout) I have owned 2 and flown at least 5. Everyone of them in the climb quickly goes from green to yellow and if you persist without a little power management will keep right on going to red. I'm with Wayne on this one. Global warming, hot outside air temps, western USA, whatever the cause, our little oil coolers or the designed placement of them are inadequate. I simply back off on the throttle and manage the climb to keep it at the top of green. Once to altitude and level then I can increase power (after a few minutes of cooling) and keep it green in the cruise (most of the time).

[Ed Cesnalis]

I used to do the throttle management routine but now I realize that the quicker I get to less than 72 degrees outside air temp the sooner I willl be be back in the green. That is the line for me 72 OAT.

 

Adam a typical departure for me that gives me oils temp issues is departing Van Nuys headed north for Mammoth. In that 20 minute climb, in the summer I am going to be hot no matter what and wandering around avoiding the climb creates its own issues.

[Adam]

Hey Roger, I guess we need to define "high". To me, "high" is out of the green range and into the yellow. I'll have to look at my Dynon Skyview range settings. If I remember right (not in my plane, rather on my sofa!) at 230 my Skyview goes from green to yellow. At 250 it goes to red. If you say 240 to 245 is ok in a climb that means I'm climbing in yellow. 245 is closer to red than green. I have been backing off throttle a little bit at 235 and have not been letting it go that high. Lately OAT's here at the ocean have been in the low 80's. At 100 I'd be the failure (not the plane)(I know, its a dry heat, I used to live in Scottsdale). Perhaps I will try to climb and see if it stabilizes at 240 or keeps going up.

 

In my case prop is set so that WOT straight and level is about 5500 to 5600. I have yet to put the ground mod on (have the 8 gauge aviation wire, waiting on the crimp lugs to deliver)

 

Reminds me... My plane always use to go yellow on voltage too (at like 13.8). I got tired of it, 13.8 is far from high on charging so I changed the setting on the Skyview to stay Green to 14.0.

[FredG]

I switched oil temperature sensor ID to #4, and my oil temp immediately displayed a temperature 15 degrees F higher than the temperature indicated when #1 was selected. That is a reproducable difference, when switching between sensor type 1 and sensor type 4. According to the table on page 5-9 of the D120 Installation Guide (for software version 5.4), Rotax factory sensors are #4.

 

So, which temperature is correct? How does one ascertain "true" oil temperature? And, why does FD deliver these planes with Sensor ID #1 selected when Dynon documentation recommends #4?

 

Fred

[Doug G.]

Rotax, the Marvel Mystery Motor!

[FredG]

According to the April 2010 Rotax 912 Operating Manual, the maximum operating limit for oil temperature is 266 degrees F. The "normal operating temperature" (for oil) is "approx." 190-230 degrees F (see page 2-5). I find no Rotax statement or recommendation about temperatures between 230 degrees F and 266 degrees F.

Fred

[FredG]

Regarding setting the oil temperature sensor ID to #4, Dynon made the same recommendation to me this past week (D120 equipped 2006 CTsw, software version 5.4). Since switching to #4, my oil temperature fluctuations have gone away. Oddly, when I switch back to #1, it no longer fluctuates on that setting, either (I know, it makes no sense). But, as noted above, the temperature values are 15 degrees higher.

 

I was having the known problem with fluctuating oil temperatures, especially above 200 degrees, but careful attention to grounding minimized it (but didn't make it go away entirely - I was still having fluctuations of +/- 2-3 degrees F). Still, a lot better better than the 20 degrees F variability that I had before making sure all grounds were tight.

 

I would be very curious what others observe by entering the sensors menu of the Dynon D120 operating system and switching from sensor #1 to sensor #4. Is the indicated temperature difference of 15 degrees a universal observation?

 

My questions, above, remain - 1) how does one ascertain "true" oil temperature? and 2) why does FD deliver these planes with Sensor ID #1 selected when Dynon documentation recommends #4? I can ask FD USA the answer to the second question.

 

One thought I have regarding measuring true oil temperature is to run the engine up to temperature on the ground, with no cowling, shut down the engine (but keep the D120 energized) and then measure with a non-contact thermometer ("laser thermometer) the temperature of the housing into which the oil temperature sensor is attached (and compare to the D120 value). Of course, that is surface temperature, not internal temperature, but with the prop stationary, they may be close. Another approach might be to measure the temperature of the oil in the tank.

 

Any suggestions?

 

Fred

[FredG]

Roger, thanks, should be interesting.

fg