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High Oil Temperature Experience

Steve Pierce

Steve Pierce

BENEFACTOR
Graham, TX
Anybody have any experience with a front mounted oil cooler and a Sutton exhaust? I have a new LyCon 160 hp O-320, new baffles, Sutton exhaust, new aluminum Cub cooler etc. that is heat up the oil to 245 degrees in 30 minutes with an OAT of 87 degrees. Removed the filter adapter and vernatherm and installed screen and viscosity valve. Duct taped around the cooler so no air goes around it to no avail. LyCons questions how close the cooler is to the muffler and being that all my experience that I can remember with the Sutton exhaust has been with a rear mounted cooler I wondered if anyone is running this combination and have had any issues. Kinda grasping at straws at this point, next step is to install a stock exhaust system and see what that does.
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I have not seen that setup before. I do prefer front mounted coolers. How about heat shield/deflector behind the cooler to help with heat and airflow.
DENNY
 
There is an AD on the oil cooler hoses on the PA28s and PA32s. AD 95-26-13. Could exhaust heat have damaged a hose or could the hose inner liner have been cut at assembly causing a flap stopper? jrh
 
Hoses are new, checked them when we assembled them but worth a second look. Gonna pull them and slide the borescope inside and see. Covered the starter hole and that didn't help. Think I am gonna rap the muffler shroud in a welding blanket and remove the exit SCAT hoses and see it the radiant heat might be contributing.
 
Steve, I have the old Piper cooler in the front, Sutton exhaust, 150hp, on my 12. Temps run around ambient + 100. Fine in the summer, sort of cold in the Ca. winter.
 
Talked to Brian Sutton and he reminded me of the two exhaust pipes on the original exhaust system that run across the back of the oil cooler would radiate heat. The shroud over the Sutton muffler should be considerably cooler since the air is coming between the shroud and the muffler. I am going to investigate the oil lines and cooler tomorrow.
 
It would be my opinion that the oil is not going to the cooler for what ever reason. On my 720 it was a worn vern seat and brand new vern that was bad. Replaced them both with new and shazam.
 
I have the same setup on my bird no problem at all and i have the aeroclassic oil cooler ( less fin) oil temp all the time at 185 f ,the only time it got way high is when my cam started to go ...
 
Steve,

Sorry for the late reply. Don't have a better pic handy, but yes, Sutton and front cooler here in Yuma. Only obvious difference is no starter hole, but you already tried that... Our experience is that the cubs here in the desert with rear mounted coolers tend to run higher oil temps? as do the couple with stock exhausts.

Take care, Rob

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Sutton exhaust and front mounted alum cooler on my 12 with O320. Seems to work fine, including in 100 deg + weather. For that reason I don't think it's a radiated heat issue. Let us know what you find!
 
Fortysix12 said:
It would be my opinion that the oil is not going to the cooler for what ever reason. On my 720 it was a worn vern seat and brand new vern that was bad. Replaced them both with new and shazam.
Click to expand...
Brand new vernatherm. Replaced it with a viscosity valve which sends all the oil through the cooler and verified with oil lines off I have flow through the cooler.
 
Removed the brand new Sutton exhaust yesterday and installed the original exhaust. No change other than fewer rpm on take-off. Gonna check air pressure drop through the oil cooler with an airspeed indicator and if that is good swap the cooler. This is crazy.
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could you please post a photo of a viscosity valve and a vernatherm I though I knew which was which,but now not sureThanks
 
This is the viscosity valve. Closed unless there is an obstruction.
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This is the nut the at it is held in by.
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So today I verified that there was proper flow through the cooler. Used some old 3/16" pilot line out of a Super Cub wing and an airspeed indicator. Ran a line in front of the cooler scared to the rear.
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And another at the exit of the cooler.
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Run into the cockpit to an air speed indicator.
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Airspeed indicated 75 mph from the front of the cooler and 35 mph behind. According to Loren at Lyons this is enough airflow so that is not the issue. Talked to Niagara Air parts about how to test their cooler and what were good airflow numbers but they didn't know. Installing another cooler tomorrow and see if that changes anything.
 

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just some random thoughts

oil level too high/wrong dip stick? don't ask how i know this.... :)

spun/spinning main bearing?/metal in screen? (most common right after rebuild)
 
Just realized the cooler is under the engine. So it is exhausting its air into the same area the air from the cylinders flows into. With your airspeed measurements before and aft I wouldn't have expected that much difference, but I also have no practical experience in this area. The few front mounted coolers I have seen are on Cherokees and get their air from the cylinder intakes. My small experience with Champ and Chief engine cooling and changing the size of the bottom opening in the cowl makes me think you need a duct from the rear of the cooler to the hot air outlet in the bottom of the cowl so the hot oil cooler air doesn't have to fight the hot cylinder air to get out. I hope that made sense. jrh
 
mike mcs repair said:
just some random thoughts

oil level too high/wrong dip stick? don't ask how i know this.... :)

spun/spinning main bearing?/metal in screen? (most common right after rebuild)
Click to expand...
Amount of oil put in the sump matches what the dipstick shows. When it was run on the test cell there was a 14 psi difference in oil pressure between the normal oil pressure pickup and the oil galley at the front of the engine. This is normal and if much different would indicate a problem like a spun bear g. Also no metal in the screen.

Keep the thoughts coming, somewhere there is an answer.
 
N86250 said:
Just realized the cooler is under the engine. So it is exhausting its air into the same area the air from the cylinders flows into. With your airspeed measurements before and aft I wouldn't have expected that much difference, but I also have no practical experience in this area. The few front mounted coolers I have seen are on Cherokees and get their air from the cylinder intakes. My small experience with Champ and Chief engine cooling and changing the size of the bottom opening in the cowl makes me think you need a duct from the rear of the cooler to the hot air outlet in the bottom of the cowl so the hot oil cooler air doesn't have to fight the hot cylinder air to get out. I hope that made sense. jrh
Click to expand...

I have thought of adding more cooling lip to the bottom of the cowl but this is a stock cowling with new tight baffles and I am told the air flow is correct.
 
Steve I have two oil coolers the old one up front and cub crafters behind the left cyc. on a 50 degree I am lucky to get 140 on the 100 degree day pulling banner at 45mph I saw 215 .85 degree day at cruse 160. I have worked with airflow on the three cubs a lot its not that.like Mike said got to be something in engine.these things airflow I fly at 45mph the only thing that get to hot is the ex valve area the cyl temp is ok . what is the cyl temp?
 
Steve, maybe loose liner in the hose that could block oil when flowing but not be apparent to visual inspection??
 
Put the Sutton exhaust, oil filter adapter, vernatherm and another light weight oil cooler on it. No change. Bumped the oil pressure up, no change. Loren at LyCon got some data from a contact at Piper. Appears that Piper used an airspeed indicaator with the pitot in front of the cooler and the static behind the cooler on the Pawnee and the Super Cub. At 100 mph that AS indicator should show 65-80 mph. I got 74 mph when the airplane was indicating 90-95 mph on the aircraft aispeed. Going to install my test rig on another Super Cub today to compare the data. After a week of working on this I am getting frustrated.
 
Steve,

We had a bear of a time with Oil Temps on an a Cub that had 31's,borer, 160hp,60 gal fuel, and no cowl mods except for the bottom cowl lip. Flight testing in Boise, the oil temps shot to 225F and climbing ,ambient was mid to upper 80s. DA around 8500 as I recall. I had to fly very conservative to control temps. We concluded that part of the problem was the lack of airspeed VS power settings, just not enough air. Can't remember if Dave's cub is rear or front oil cooler.

Something I noticed on CC Top Cub is they don't box the carb and aircleaner. I built my airplane with this concept The ironic thing is when I did install a very custom carb/aircleaner assy, my temps went up not down. I concluded I was making more power because of ram air effect, this box doens't leak much, still my original design allowed the air to enter the bottom and go out the back. might try it. A two channel recording manometer is worth it's weight in gold.

Dave, what ever became of the oil temp issues?
 
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