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Old 08-25-2021, 06:01 PM
FireMedic_2009 FireMedic_2009 is offline
Join Date: Nov 2016
Location: Tampa, FL
Posts: 235
Default Oil Temp question for RV3's & 4's

The builder installed an oil cooler shutter with the oil cooler installed on the rear baffle behind Cylinder #4. I've closed the shutter fully and the temp is still in the 174 deg F range. I've heard you can remove the oil coolers from the RV3's and 4's. FYI. My oil temp sensor is a UMA brand and I called the manufacturer and got the ohm values for various temps. The ohms vary about 0.5 ohms per 5 deg F, if I remember correctly. The manuf stated a min of 20 gauge wire should be used and the connection should be soldered instead of using connectors to extend the leads of the sensor. I noticed my oil temp before starting the plane was about 17 deg F higher than the OAT. After changing the wire gauge from 22 to 20ga and removing the connectors the oil temp was close to the OAT temp before starting.

How many of you don't have temps above 180 deg F?

How many of you don't have oil coolers and what are your temps in the summer?

RV-6A IO-320 FP sold
RV3B O-320 160hp
Donated 2018 and continue annually
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Old 08-25-2021, 06:12 PM
dnh98221 dnh98221 is offline
Join Date: Oct 2018
Location: Anacortes
Posts: 28
Default Oil temps

I have the same setup on my -3B and when I close the shutter my oil temps go up about 5 degrees, typically from around 165 or 170. I struggle to keep oil and cylinder head temps warm enough. I should probably remove my oil cooler and save some weight and space…

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Old 08-25-2021, 06:22 PM
Rv3Dave Rv3Dave is offline
Join Date: Jul 2016
Location: Florida
Posts: 62

Same with my 3B, even in summer I close the oil cooler shutter in cruise to get the oil temp up to 170. Takes forever to get the oil warm enough for takeoff in the winter. O-320 with oil cooler behind #4.
I have considered removing the oil cooler. Hope some one who has a 3 without an oil cooler will chime in.
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Old 08-26-2021, 05:13 AM
Skysailor Skysailor is offline
Join Date: May 2011
Location: Atlanta, GA
Posts: 290
Default Vernatherm

Have you guys thought about removing your vernatherm valve and checking it on the stove suspended in a pan of water with an accurate thermometer? The vernatherm is just a thermostat for oil and should control oil temperature by controlling when and how much oil is sent to the cooler. If it were to be failed in the open position you would have the symptoms you describe with long warm ups and a struggle to maintain oil temperature. If it functions properly the oil cooler shutter should not be necessary.
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Old 08-26-2021, 08:19 AM
lr172 lr172 is offline
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,555

Originally Posted by Rv3Dave View Post
Takes forever to get the oil warm enough for takeoff in the winter..
You may want to re-think your minimum oil temp, especially if using a multi-vis oil. I do not use 100* like many, but instead use a minimum CHT (I do worry about differential expansion rates between piston and cyl wall creating scuffing). From my research, there is simply no rational justification for a 100* minimum OT on a non-radial engine running 20W50 oil. I fly a lot in the Midwest winters and couldn't imagine idling on the ramp for 15-20 minutes like some of my neighbors. My 320 has 800 hours now and oil pressures haven't dropped at idle since overhaul, so unlikely I am trashing the bearings in my engine. I do use oil pan heaters and my OT at take off, after getting the CHTs that I want, is usually between 70-85 in the winter.

If I was running straight 100 oil in the winter, I would think differently. The 100* min OT guideline has been around for many decades and keeps perpetuating eventhough oil technology has vastly improved. You will not find that recommendation in the Lyc Operators Manual. I am guessing it is a hold over from the radial days before multi-vis oil was created, but it is nowhere to be found in the Lyc documenation. The Lyc manual is clear on what oil grades to use based upon ambient temps though and they do not recommend 100 oil in winter temps.

N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 08-26-2021 at 08:49 AM.
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