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  #1  
Old 06-11-2019, 05:03 PM
aviator289 aviator289 is offline
 
Join Date: May 2019
Location: Scottsdale
Posts: 3
Default RV-6A O-320 high oil temps

Just purchased a 6A with a O-320 and all I can say is WOW, I have owned 8 factory aircraft from 172s to a C414 and the bang for your buck in a RV just cant be beat, Its hard to believe what these airplanes can do and I am hooked!, here are the details of my issue:

Engine : O-320 / 160 hp @ 2700rpm 360 hrs since factory new limit overhaul by certified shop, oil cooler is standard 4 1/2" thick stewart warner mounted on baffle at back of engine. This was a high quality build by a couple of engineers and the baffling looks good. Aircraft now based in S. Arizona so looking for maximum cooling options.

Prop: Catto composite prop,

At 3000-4000 msl with OAT at 77-87F Oil temp is running at 210 to 217F even at lower power settings, lycoming lists the O320 normal cruise oil temp at 185-210F with a max continuous temp of 245F.

Although temps are below max they are above normal spec and I would like to get the oil temps down.

Does anyone have experience going from the baffle mounted 4 1/2 inch oil cooler to the firewall mounted larger 7" thick (the 20006A oil cooler for IO360 and 540 engs) with a 4" air duct and how did it help high oil temps?

Last edited by aviator289 : 06-11-2019 at 05:56 PM.
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  #2  
Old 06-11-2019, 05:33 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 3,686
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No experience with what you propose. Can you share CHT's and how your oil cooler is fed, particularly the hole size in the baffles?

Are your battles tight? Well sealed?
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Kyle Boatright
Atlanta, GA
2001 RV-6 N46KB
2019(?) RV-10
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  #3  
Old 06-11-2019, 05:53 PM
aviator289 aviator289 is offline
 
Join Date: May 2019
Location: Scottsdale
Posts: 3
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Kyle, the oil cooler is mounted to the baffle above the left rear cly.and all of core is exposed to airflow, baffles look good, all 4 CHTs in cruise are below 350F
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  #4  
Old 06-11-2019, 07:05 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 3,686
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Quote:
Originally Posted by aviator289 View Post
Kyle, the oil cooler is mounted to the baffle above the left rear cly.and all of core is exposed to airflow, baffles look good, all 4 CHTs in cruise are below 350F
I have the standard cooler in the same place and would see 365 CHT's and a 185 oil temperature in the same conditions from my O-320.

Which oil cooler (make and model) do you have?
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Kyle Boatright
Atlanta, GA
2001 RV-6 N46KB
2019(?) RV-10
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  #5  
Old 06-11-2019, 07:55 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 3,988
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I have an SW cooler in the same position on my 6A with a 320. I never see anything over 185 in the summer, with CHT's in the 350 range.

First guess is a bad vernatherm or deformed seat on the case that the vernatherm tip goes into. ECI filter adapters are known to have issues aligning the vernatherm with the hole. Second guess and much less likely is a partially blocked cooler. When the vernatherm gets near 180, it closes the bypass, forcing the oil through the cooler. When they fail, they won't extend, or only partially extend, and oil doesn't flow through the cooler. Yours is likely partially closing, providing some cooling. This is a common failure.

If baffles were bad, you would see high CHTs as well and you are not

Baffle mount will typically perform better than one fed by a duct.

While 210 is beyond the normal range, you should have no issues with your oil, assuming a 35-50 hour drain interval. Oil does not seriously break down until 250-260. Don't recommend ignoring it, just indicating that you don't need to ground the plane.

Larry
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RV-10 in progress

Last edited by lr172 : 06-12-2019 at 07:06 AM.
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  #6  
Old 06-12-2019, 06:35 AM
Southern Pete Southern Pete is offline
 
Join Date: Jul 2015
Location: England
Posts: 24
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I would suggest your problem is more likely to be lack of air flow through the cowling. If you add some louvres to the bottom of the cowling more air will pass through lowering the temps (CHT & oil). My CHTs dropped by 40deg and oil by 15 deg.
Pete
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  #7  
Old 06-12-2019, 01:38 PM
aviator289 aviator289 is offline
 
Join Date: May 2019
Location: Scottsdale
Posts: 3
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Thanks for the feedback Larry and I think you nailed it.

My O-320 was overhauled in 2000 and since then Lycoming has released an updated veratherm / oil cooler bypass valve in May 2016 per Lycoming Service Instruction letter 1255A. This letter indicates that this valve should be replaced with the updated Lycoming veratherm / bypass valve p/n 53E22144 when high oil temp is noted. The information in this letter applies to all Lycoming engines used in Vans aircraft.

This part is $339 from ACS and I have one on order. I will update with how things work out once I replace the valve and hope this helps anyone else dealing with excessively high oil temps.

Tom Newman
RV-6A
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