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Oil temperature issue during climb

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HB-YNK

Joined: 30 Sep 2016
Posts: 6

Posted: Sun Nov 14, 2021 1:17 pm Post subject: Oil temperature issue during climb

Hi all,



I'm having some trouble with my oil temperature during climbing. The oil temperature rises quite fast into yellow arc and would rise further without interrupt the climbing phase. During horizontal flight everything is good.



I do have an Rotax 914, with the lowered oil radiator and a small lip at the outlet behind the radiator. Last flight was below zero degrees and still a big issue. I guess it all comes from the angle of attack, that gives turbulence's into the main air channel.



Do you have any ideas how I could improve this issue?



How about removing the oil thermostat?



Many thanks



Marcel



__________________________

XS Mono, Rotax 914, HB-YNK

_________________
_____________________________________
Marcel Bodmer

Europa XS Monowheel
HB-YNK

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Sun Nov 14, 2021 3:46 pm Post subject: Re: Oil temperature issue during climb

Hi Marcel I'm sure others will chime in, but here's some info from someone not yet flying XS Mono with 914: If you didn't already do so, read Bud's excellent Cooling 101 on Club Website. Let's start at the radiator intake: Did you smooth out just inside cowl? Foam and glass is what we did. As far as radiator duct, it needs to be sealed really well. We used Mcfarland Cowl Saver Baffle seal which has a Teflon coating on one side, you can score it to allow for better bending. You can score both X and Y for compound curves. We needed to glass better contact surface in a number of areas to get good sealing. We used Silicone foam to seal radiators to duct and radiator to bottom cowl. We sealed the oil lines to the radiator duct by installing 2 layers for fire-sleeve. We have a cowl flap that completely closes and opens with bottom at a 30 degree angle hanging down from cowl in down position. We have the radiator duct sealing really well to cowl on their 3 sides at the intake.

https://1drv.ms/u/s!Ah1S270Nwg9V0necoDcgMalF8veN

https://1drv.ms/u/s!Ah1S270Nwg9V0z_WjtOJmsdYoYhf

https://1drv.ms/u/s!Ah1S270Nwg9V3HOK0271vAgyWHMQ

https://1drv.ms/u/s!Ah1S270Nwg9V02UKAAsv6tfJCRbh



Good Luck

Ron P.

budyerly@msn.com

Joined: 05 Oct 2019
Posts: 286
Location: Florida USA

Posted: Sun Nov 14, 2021 5:38 pm Post subject: Oil temperature issue during climb

Marcel,



If you have dropped your Mocal oil cooler supplied by Europa, as Ron said, ensure you seal your duct bottom, and sides.

As you know the oil cooler is not as wide as the glycol cooler.  The gaps between the metal duct and the fiberglass cowl must be closed or oil cooling is ineffective.

If you shine a light you should only see light coming through the fins.  No where else.



Also, as a reminder, please check your oil temperature sender.  I use a separate thermocouple or infrared thermometer to verify the sender/gauge is working correctly.  You can swap the oil and cylinder sensors if you suspect the oil temp probe is not working.  See my troubleshooting manual on my website www.customflightcreations.com



If the ducting is tight, and the sender is good, you potentially have a supply or return blockage.  If you have an oil thermostat in the line, it may be not working properly or closed so the return line is blocked by the thermostat.  It is possible to incorrectly hook up the oil lines creating a restricted flow.  Also check your oil tank vent line is clear and not holding pressure.



Personally, my 914 even in hot climates never runs over 250F degrees on a hard climb.  Normally the glycol will climb to 245F (roughly boiling point in the heads) well before the oil gets to the limit.



I hope you find the issue.



Best Regards,

Bud Yerly



--

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Mon Nov 15, 2021 8:29 pm Post subject: Re: Oil temperature issue during climb

The engine in my mono is the 912uls so could be different but it runs very cool even in the Florida heat. I was concerned given reports of cooling issues in the Europa but I can attest the system works very well. In fact, my engine tends to run too cool. What I did based on Bud’s guidance:



1.- Absolutely seal the duct to cowling edges and all areas around the coolers to ensure air will only go through the coolers. 

2.- The sides of the coolers are sealed as Bud described using aluminum baffles. 

3.- I have a baffle at the bottom of the water cooler that seals against the oil cooler front face forcing all air through the water cooler and the bottom of the oil cooler which is lowered as far as possible. This does limit the flow through the upper part of the oil cooler but provides more pressure differential area to the water one. Works well in my case. But key is to ensure no pressure differential is lost. 

4.- I was very picky about creating nice air flow diffusers at the duct inlet. Both top and bottom. Not the sides which are just sealed with baffling seals against the cowling. The upper diffuser and duct sides are tightly sealed against the cowl to prevent any air spilling out. 

5.- I made a completely different firewall design than the one Europa calls for based on Bud’s guidance. I am super happy with it as it provides a lot of space behind the engine and provides a larger and smoother air exit. It was very easy to make and install. Dunno why Europa doesn’t just do it this way. I am sure this is really helping overall air flow through the engine compartment.

6.- Cowling is stock. No modifications except the inlet diffusers. I never opened the gills but the starboard naca scoop is open. 



As Bud said and I learned the hard way too, always check sensors first!



Chris

HB-YNK

Joined: 30 Sep 2016
Posts: 6

Posted: Tue Nov 16, 2021 12:20 pm Post subject: Re: Oil temperature issue during climb

Dear all



Thanks for all tips and support. 

Some additional information I forgot to write.

In the past i had some issue with hot CHT on ground, so i wasn't able to get airborne within green arc. To solve this issue I already did this work:

- get familiar with Bud's Cooling 101

- Smooth out the inside cowl

- Small lip on outlet behind radiator

- Sealed everything possible around radiators, just not sure how my seal is working at the interface the the cowling



I will check the sensor, the thermostat and the oil tank vent lines.



But does anyone have experience to fly the 914 without thermostat?

(at) Bud, Do you fly with an thermostat?

(at) Chris, do you may share a picture too?



Many thanks

Marcel

_________________
_____________________________________
Marcel Bodmer

Europa XS Monowheel
HB-YNK

budyerly@msn.com

Joined: 05 Oct 2019
Posts: 286
Location: Florida USA

Posted: Tue Nov 16, 2021 12:47 pm Post subject: Oil temperature issue during climb

Marcel.

I fly without the oil thermostat all the time.  I sit for about 2 minutes longer waiting for the temps hitting 100F.   Climbing to 10000 I just hit 200F on the oil and 245 on the HT.



Bud Yerly



--

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Tue Nov 16, 2021 4:19 pm Post subject: Re: Oil temperature issue during climb

Marcel, unfortunatedly I couldn't find a good picture of the baffling on the radiators and the difusers. The oil cooler has two baffles on the sides (that I do show a picture of) and one on the bottom that is flexible to bend and provide seal pressure against the cowling bottom. If I remember to take pictures of the existing baffles when the lower cowling is off I will.



You can also see that the sides of the water cooler have been filled with firewall material and black RTV. The black RTB is bonded to the firewall material but not the duct for easy removal.



An important one is at the bottom of the water cooler and butts against the oil cooler front. Sealing that large gap between the two. So the high pressure in front of the coolers forces air through the lower part of the oil cooler and the entire water cooler. Since the oil cooler is not sealed at the top, all the air coming out of the water cooler has a low pressure area to exit unrestricted. This eliminates the flow over the upper part of the oil cooler but that is OK in my installation as the oil seems to remain cooler than the coolant. You could reverse it (put in in the upper edge of the oil cooler and butt against the rear of the water cooler). This would force more air through the oil cooler and less through the water one.



This may not apply to your case but it works for me as my oil stays cool. 



Chris

Chris duct 2.jpg

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You can see the baffle at the sides of the oil cooler.

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Chris Duct.jpg

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Water cooler sides and duct to cowling

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Chris Europa Firewall.jpg

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Bud Yerly mono firewall. A lot of small pieces but works great.

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rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Wed Nov 17, 2021 9:40 am Post subject: Re: Oil temperature issue during climb

Hi Chris Curious, what's the tan colored stuff by your baffle seal on the white paint?



Thx. Ron P.

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Wed Nov 17, 2021 8:01 pm Post subject: Re: Oil temperature issue during climb

Ron, it’s just leftover firewall material. The radiator was a tad narrower than the duct and needed something to fill the gap.

Chris

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Thu Nov 18, 2021 10:23 am Post subject: Re: Oil temperature issue during climb

Hi Chris



 The tan that I'm curious about is on the first pic you posted, on the outboard side of the radiator duct on the left side just above the black baffle seal. Perhaps adhesive? Or?? Thx. Ron P.

n7188u

Joined: 15 Nov 2015
Posts: 404

Posted: Thu Nov 18, 2021 10:26 am Post subject: Re: Oil temperature issue during climb

Oh, I see what you mean.



There is actually nothing there. Must be a shadow from the flash  The seal is just riveted in place.



Regards,

Chris

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