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-   -   High oil temps (https://vansairforce.net/community/showthread.php?t=148212)

trifield 04-03-2017 06:26 AM

High oil temps
 
Just to add my experience with high oil temps, my motor is an IO320 eci kit engine with squirters rv7a. I have been chasing hi temps since the build now with 140 hrs on the clock . Temps up to 118c and rarely under 102c , chts ok.basically unmanageable
Relieved lower cowl with no change to temps, fitted 13 row remote cooler helped but still to high. When I built the motor I never adjusted the oil pressure relief valve as it was screwed up to maximum so I figured that wasn't a bad thing.
By chance I just fitted a c/s prop and was having surge problems and I deceided to adjust the oil pressure. Oil temps down to 86c constantly . We have been flying with summer temps in the 35c plus range and I have seen 108c on climb then start managing it with air speed and decreasing into the mid 90c .
I guess it was not getting oil cooler saturation.
I'm happy with these figures .
I hope this may help .

DanH 04-03-2017 07:21 AM

Quote:

Originally Posted by trifield (Post 1162821)
....I decided to adjust the oil pressure. Oil temps down to 86c constantly.

Greg, what was the original pressure in cruise, and what is the new pressure?

Timberwolf 04-03-2017 11:23 AM

hmm. My oil pressure is at 90-95 in cruise I believe.

I took my leaf blower up and blew it into the cowling then stuck my hand behind the cooler. It doesn't feel like much air is getting through it with the 3" scat. The 7 row will be here today and I'll see what difference that makes before I fab up a new fiberglass plenum and the 4" scat.

Sixgun 04-03-2017 07:11 PM

Oil cooler
 
Quote:

Originally Posted by Timberwolf (Post 1162429)
Hey guys thanks for all of the replies. Back at a computer so I can give a little more detail. Temp probe verified with boiling water, new baffling material and all seems well sealed. Ducting is 3" scat right into the cooler. Ducting all to the cooler and the cooler face is well sealed with no leaks. It attaches to the back of the baffling with a tig welded aluminum tube to a flat plate, not exactly contoured. Engine does have oil jets and timing is verified at 20*. Looking at the chart for the X-series coolers, it looks like they recommend no less than a 13 row for oil squirters. I only have a EI scanning egt/cht gauge so not able to log the temps, but I do believe they all evened out one I powered back at cruise. I haven't had a chance to really get up and check with different temps, but all this was around 80 degress OAT. If I remember correctly I want to say my CHT on my #1 was under 290 with everything else leveling out around 340. I'll try to get a flight in today to verify.

Some observations...
This plane doesn't have the front baffle right behind the ring gear. I just cut one out with the plasma and baffling material will be here Monday. Though some air could be escaping to the lower cowl from here, I have it pretty well sealed up with RTV.

Looking at a buddies RV-7 I see he has the ramps on his top cowl. I suspect to speed the air past the front cylinders and make it all the way to the rear cylinders to prevent this very issue.

I've read where others have had some of the same issues and people have put on a firewall cooler as well as the one behind the #4 cyl. I have the previous owner shipping me the 7 row that went behind #4 in hopes that I could run them in series to get the temps down until I can fix it correctly

https://drive.google.com/open?id=0B_...C1JZDFjSWNDVlU
https://drive.google.com/open?id=0B_...jhuYTdHcTFUaWM
https://drive.google.com/open?id=0B_...UxxNnlRSjMyVmM

Looking at the 2nd photo I see you don't have an inlet screen over the air entrance. This is asking for trouble . Consider what a bird entering that could do to your oil temp if it went in there. Have you checked the cooler for any obstructions ?. This might be the source of your high temp. Put a screen cover over that air entrance ..

Timberwolf 04-03-2017 07:19 PM

Not sure I've ever seen a screen on any aircraft for an oil cooler. If I took a bird and saw the temps rise, I would be landing to check out what was going on, but point taken. Checked, nothing is obscuring it.

I got the 7 row in tonight in series and it lowered temps to 200. I can live with that to get it down to SNF until I can get the 4" scat on the 9 row. I think I may be putting in the ramps as well once I get back. Something still isn't right as far as flow in the cowl because despite the change, the #4 is still at 295 on the CHT after leveling off with the others 336-345. I think something needs to be done to ensure the air is flowing all the way to the back and getting through the coolers.

DanH 04-03-2017 07:31 PM

Quote:

Originally Posted by Sixgun (Post 1163024)
Looking at the 2nd photo I see you don't have an inlet screen over the air entrance. This is asking for trouble . Consider what a bird entering that could do to your oil temp if it went in there. Have you checked the cooler for any obstructions ?. This might be the source of your high temp. Put a screen cover over that air entrance ..

A foreign object on the cooler face could be a problem, but screens are really obstructive. Take a look at the charts ("open area") here:

https://www.mcmaster.com/#standard-m...lters/=171kr9k

Quote:

Originally Posted by Timberwolf (Post 1163029)
Something still isn't right as far as flow in the cowl because despite the change, the #4 is still at 295 on the CHT after leveling off with the others 336-345.

Before you make yourself too crazy, swap probe locations; move the #4 probe to another cylinder and see if the indication moves with it.

Timberwolf 04-03-2017 07:56 PM

back to the basics. I like it. I'll check tomorrow

trifield 04-04-2017 05:07 AM

Oil temp sucsess
 
Dan , the pressure was 75 psi on cruise now it's around 65 psi ,its quite amazing I think that it's been such a dramatic improvement on my oil cooling , one would think that fitting a 13 row cooler over a 7 row would do the job but the pressure adjustment has done the job.

tsneidin 04-04-2017 09:35 AM

lower pressure = lower oil temp
 
Can someone explain why this would be as it seems counter intuitive.

N941WR 04-04-2017 10:49 AM

Quote:

Originally Posted by trifield (Post 1163103)
Dan , the pressure was 75 psi on cruise now it's around 65 psi ,its quite amazing I think that it's been such a dramatic improvement on my oil cooling , one would think that fitting a 13 row cooler over a 7 row would do the job but the pressure adjustment has done the job.

Quote:

Originally Posted by tsneidin (Post 1163184)
Can someone explain why this would be as it seems counter intuitive.

Dan Correct me, if I'm mistaken...

By lowering the oil pressure, I believe you give the oil more time in the cooler, to transfer its heat to the moving mass of air.


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