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Rear oil cooler hose routing

JB

JB

FRIEND
Willow Creek, Alaska
Been struggling this summer with oil temp getting too hot. I was wondering if oil cooler hose routing would make any difference? I have been noticing many cubs with the top port of the cooler being routed to the bottom connection on the accessory case. Mine is connected to the top. I have a rear mounted 7 fin niagara oil cooler. Had a vernatherm which mechanic recommended I remove and go back to the plunger. Didn't make a difference. Check mags and all is good. Oil cooler had a sheet metal shroud in front of it with a hinged top that was controlled by a pull cable in the cabin. I believe the intent was to direct ram air to the cooler instead of hot air from #4 cylinder. Removed that and didn't change anything. I have a leading edge exhaust, another mechanic said that Paul Claus had that and couldn't keep the thing cool so they removed it. Is this a common issue? Looking for some suggestions.
 
Here are a couple of pictures of a baffle which is up tight against the rear side of the #4 cylinder. The top of the baffle is facing forward to direct cool air into the cylinder. This allows the cooler air up near the top cowl to pass through the oil cooler without any added heat from the #4 cylinder. The temp seldom goes over 190. The top of the cooler is also tilted back to more efficiently allow the cool air to pass through the cooler. IO-360B engine.

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This was how mine was. Removed it to try and give it some more air but there was no change.
 

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In my mind I see two things with yours. The baffle in your picture was confining with the two sides restricting flow to the cooler. When you removed it you gave it a larger volume of air, but that air was heated from the cylinder first. Try a baffle which goes all the way from your side baffle to completely block the cylinder fins and an inch or more higher than the cylinder. Like my second picture. This can just be wedged in there for test purposes.

I can't give before and after information, as I built it this way from the start and it worked out perfectly on both the oil and CHTs.
 
I agree with skywagon8a. The way the internal baffle is set up restricts the airflow. Mine is set up like post #2 and works fine. Also take a look at all the Baffling for leaks. I don't think the exhaust is the issue lots of people run them with no problem, same with hose routing. Although oil temp is not a direct reflection of CHT'S they can trend together. Before a major expense of changing exhaust system I would get the 4 Cylinder CHT/EGT and make sure you are not going down the wrong road and missing another issue. Post some pictures of the engine Baffling.
DENNY
 
Thanks guys! I will give it a try. I'll also grab some pictures of the baffling. I did spend quite a bit of time sealing things up to see if that would help but didn't seem to make much difference.
 
We have an A model with an O-360 (Penn Yan STC), rear mounted Niagara and LEES exhaust. No issues with high oil temps running floats all summer. Winter requires a block off plate with a 1" hole to maintain 180 deg oil temp. I did use this aircraft for radio telemetry work requiring some significant full power climbs to nosebleed territory, still no issues with oil temps, on the other hand, cylinder temps required a close watch. I run an aerospace logic 4 probe CHT. Once I get back on station I can send some shots of my routing.

TR
 
I bought a digital manometer off of Amazon and found it very useful for seeing pressure differentials on either side of cylinders, oil coolers etc.
 
What kind of numbers should you be seeing on the meter in the different locations?
 
Lycoming says there should be 5.5 inches of water difference between the upper cowl area and the lower cowl area. I usually see 4 to 4.5 inches of water and oil temps running normal.
 
Thanks for sharing the thread from your experience I felt like I was reading my story from this summer. I will be trying the manometer.
 
If you put a light behind the engine and look through the air inlets can you see where the air might be going? Inner baffles between the cylinders are installed?

I put a fitting in the end of my hoses and drilled holes in the fitting so as not to get the pressure from the air coming in but the static pressure around it. Like the static tube on the SC pitot/static tube.
 
Baffles between the cylinders are there.

I will try again with the fittings that you suggest.

The measurements are the Differential between the locations.
 
So you are well below the needed presure differential. On my plane I had large air leaks around the air filter inlet that was presuring the lower cowl.
What does your "exit area' look like? are there obstructions?
 
Anyone have some numbers on what each should be? Maybe that could help me pin down if I am letting pressure out on top or over pressuring the lower cowl. Gonna put the light behind tonight as Steve suggested.

There is very large opening in the front baffling above the alternator.
 
Steve with that differential what was your CHT and oil temp at what Ambient temp?
 
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