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Old 05-07-2018, 05:20 PM
n518jh n518jh is offline
Join Date: Jan 2015
Location: Sun City West, AZ
Posts: 29
Cool Overheating oil

Down here in Phoenix we get hot weather along with clear skies. I have been flying my RV-12 #120330 in the summer an notice the need to be very careful to avoid going into the yellow range at 230 degrees plus. I know another RV-12 owner on the field has modified his lower cowling to move the oil cooler forward about an inch, which apparently avoids the overheating according to him. I've asked an S-LSA RV-12 owner about this over heating and been told that his plane does not go within 20 degrees of the yellow. Anyone have some comment on whether the re-positioning of the oil cooler is a good, best solution? Mark
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Old 05-07-2018, 05:56 PM
Harvey rv12 Harvey rv12 is offline
Join Date: Apr 2015
Location: Olympia WA
Posts: 156

The moving forward of the oil cooler is to put some distance between cooler and muffler. Also there is a revised muffler system the moves the muffler aft some distance to give even more distance between muffler & oil cooler. Rotax lists the max allowable oil temp at 266 deg F. I think 230f is a conservative upper limit. When I fly in temps above 80 at altitude, during climb I have seen 240 deg f, and I am not too concerned about it as it is a temporary condition.
Cyl head tems always remain at or below 200 deg f.
For comparison, I ride a large aircooled motorcycle with an accurate oil temp gauge, and during summer temps, while climbing mountain passes with passenger and baggage I see 250 deg f occasionally and the bike has performed flawlessly for 50k miles.
Tom O.
RV-12, bought flying
Hoskins Field, 44T
Olympia WA

the bitterness of poor quality
lingers long after the cheap
price is forgotten.
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Old 05-07-2018, 09:32 PM
RFSchaller RFSchaller is offline
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,395

I have been flying in PHX summer since 2012. I routinely see 234F climbing out. I end up pausing at each 2000 FT to throttle back to 4800 RPM to cool back down below 230F before the next 2000 FT step climb.

What really sucks is when I am delayed on the ground before takeoff. Overheat is a real problem then.
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Old 05-08-2018, 08:02 AM
John-G John-G is offline
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 541

Mark -

As Tom mentioned, Van's made a change to the exhaust system that moves the muffler further aft from the oil cooler. To be clear, changing over to the new muffler design not only requires a new muffler, but also replacement of the four exhaust pipes between the cylinders and muffler.

My RV-12 was one of the first kits shipped with the new muffler assembly and I have not seen excessive oil temps to be a big issue. However, here in Ohio, we are not subject to the summertime desert high temperatures you experience regularly. Living where you do, if I had the original exhaust system, I would seriously consider moving the oil cooler an inch forward before committing to the expense of a whole new exhaust system ... it may be all you need to do and it is inexpensive to try that first, compared to the cost of a whole new exhaust system.

Happy flying,
RV-12 Wings, Empennage, Fuselage, Finishing, Avionics and Powerplant kits all completed
Now Flying!!

Dues paid until September 2019

Last edited by John-G : 05-08-2018 at 08:07 AM.
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Old 05-08-2018, 08:08 AM
DaleB's Avatar
DaleB DaleB is offline
Join Date: Sep 2012
Location: Omaha, NE (KMLE)
Posts: 1,959

Mine doesn't have a lot of clearance between the oil cooler and muffler either. I don't worry if the oil temp nudges into the yellow a bit during climb. It's not too high, just the low end of the yellow range, and it cools back down as soon as I level off. Doesn't happen very often, and I don't think I have ever seen it get above 235.

Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)
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Old 05-08-2018, 12:21 PM
Jolly Jolly is offline
Join Date: Nov 2016
Location: San Francisco, CA
Posts: 46

During warmer summer months seeing 230F - 245F isn't uncommon or bad. Just normal. 230F is just the bottom of the yellow arch which just means "keep an eye on me" so I don't go into the red. Even if you see let's say 240F no big deal because when you level off and cruise it usually comes down between 215F - 225F depending on other factors.
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Old 05-09-2018, 04:29 PM
n518jh n518jh is offline
Join Date: Jan 2015
Location: Sun City West, AZ
Posts: 29
Default Engine oil overheating

Thanks for all the comments. I assume the new S-SLA on my airport that doesn't have problems is because of the new muffler location. I will work on moving the oil cooler forward, it seems to work for the other RV-12 on the field. Mark
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