172M Oil Temps to 265!!! Help!

I flew 40 hours of break-in on a brand new IO-540 last June/July. Temperatures here were in the 90's every day. I took screen grabs of the engine monitor data. Oil temps were typically in the mid-upper 180's, running at ~70% power. On the first flight, running 82% power, the oil temp was 204F.

I'd ground the airplane at 265 and find the problem.
 
WatchMeFly said:
If anyone has any other suggestions, I'd be happy to hear them
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So let me get this straight. Your shop checked all the engine indicating and control systems and found all were operating within specifications yet you still plan to fly and operate the aircraft beyond the established operating maximum limitations or follow established engine break-in procedures. At a minimum you have voided your engine warranty. At a maximum, that goes without saying.

Regardless, from a maintenance point of view, it seems very odd that a Signature-brand shop would assume such liability in telling you to operate beyond limits or not follow procedures. As to a suggestion, if what you say is true, I would not fly it until you find a more knowledgeable mechanic to find the reason for the excessive oil temps and fix your carb ice system.
 
When I hear; “ They checked everything” they usually haven’t !

Normally a oversized cooler is used on slow speed , higher power

operations such as banner towing and jump aircraft.
 
Well........We finally figured it out. And I want to clarify since some here thought that the engine overhaul shop told me it was ok to run above red line. That is not the case at all. They simply instructed that the engine will tend to run hot during break in and we just needed to manage the temps the best we could without going over 245 oil temps. What they were wrong about was the vernotherm. We pulled it out and verified that it was new. The shop told me that it was extremely unlikely that a brand new part would fail so I decided not to spend $550 testing that theory. However, someone in this thread (whoever you are, thank you a million times over) suggested a boil test on the vernotherm. Sure enough, it was bad! didn't move at all! I replaced the vernotherm and the oil temps went right back to normal.


I also just installed a Power Flow exhaust system and through that process found that my carb is jetted too lean which is not helping my temps either. I'm going to have the carb re-jetted and all should be well!

Thank you everyone on this thread for all your wealth of information. I am new to the aviation community, but I have to say........you are all ****ing AWESOME!!
 
Re: re-jetting? What I believe you mean is increasing fuel flow. Easily done with a reamer. The main jet in a Marvel Schebler carb is a simple brass pipe. Don’t let your maintenance guys fleece you for fixing that.
 
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WatchMeFly said:
... I also just installed a Power Flow exhaust system and through that process found that my carb is jetted too lean which is not helping my temps either. I'm going to have the carb re-jetted and all should be well! ...
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No surprise. Any exhaust system that improves volumetric efficiency enough to give a measurable power boost, will run leaner because there's less restriction, thus less vacuum, through the carburetor. All else equal of course. Full rich at sea level standard conditions must be rich of peak power in order to handle negative DAs and provide some cooling effect.

Stewartb said:
Re: re-jetting? What I believe you mean is increasing fuel flow. Easily done with a reamer. The main jet in a Marvel Schebler carb is a simple brass pipe. Don’t let your maintenance guys fleece you for fixing that.
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Dan Thomas said:
That "pipe" is the nozzle. The jet is deeper inside the carb, and is drilled to a very precise, tiny hole size.
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With the cars I've tuned in the past, the carb jet is an orifice that screws onto the end of the pipe, having a calibrated/sized hole to determine flow. Some of the jet pipes also have a tapered screw entering through the side of the pipe that partially obstructs the fuel flow. Rejetting is a simple process of replacing the end cap orifice or turning the adjustment screw.

Does one really adjust the full rich mixture in our Marvel carbs by reaming the pipe!? I would expect a full rich mixture adjustment screw.
 
The brass pipe holds the main jet. To increase fuel flow you can “drill it out” but the tool of choice is a straight reamer. The first time my jet got reamed was by a local shop as directed by Continental. It needed more love later so was repeated. It’s a VERY simple repair.

The slotted barrel is the mixture control. That barrel rotates in the hole in the bottom and restricts fuel flow to the jet. Caveman technology but it works very well.
 

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What is your oil consumption? Breaking in of the rings doesn’t take long, but an engine is not really broken in until 50 or 100 hours.

It has been stupid hot in TX lately with temps barely declining at all the first 2-3000 feet. Since it’s around ISA +25 or more, wouldn’t expect low oil temps but 265 is redline or thereabouts. Wouldn’t be surprised with such values after landing but would hope a bit lower in flight.
 
With those kind of oil temps and the fact that it was flown with those temps during the critical break in period I would expect the cylinders to be glazed and oil consumption high. The fix is to pull the cylinders and have them reamed. Repeat the break in process. The key to low oil consumption is to fly the engine hard but keep it cool the first 10 hours.
 
Jeff767 said:
With those kind of oil temps and the fact that it was flown with those temps during the critical break in period I would expect the cylinders to be glazed and oil consumption high. The fix is to pull the cylinders and have them reamed. Repeat the break in process. The key to low oil consumption is to fly the engine hard but keep it cool the first 10 hours.
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CHT’s are a bigger driver of glazing than oil temps.
 
kyleb said:
CHT’s are a bigger driver of glazing than oil temps.
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Certainly true but 265 degree oil temps will raise CHT’s significantly. Cylinders are cooled by air and oil. In addition heat in the block will transfer to the cylinders.
 
Dan Thomas said:
That "pipe" is the nozzle. The jet is deeper inside the carb, and is drilled to a very precise, tiny hole size.

View attachment 120160

The criticality of that tiny hole is evident in this thread:
https://vansairforce.net/community/showthread.php?t=20875
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Exactly^^^^^^^^
Reaming a jet will change the flow for sure but not always in the direction you would think.
I was a racer and I have always ran mechanical fuel injection. I have a flow setup that I can compare pills which are "jets" in a injection system. I flowed every pill and even though they are the same number they will flow slightly different from one another. Reaming one would totally screw it up. I ran both Crower, Kinsler and PSI injection in the last 30 years. I had complete set of pills for each engine that were flowed by me so I knew for sure if I was "jetting" up or down. I would change them all through out the day depending the weather.
 
Familiar with a #30 reamer? Worked great in my airplane’s carb. Simple fix for a common problem. No theory, just a pirep.

My other airplane has Airflow Performance injection. The flow at takeoff is per Lycoming spec. To reduce it in cruise I use the mixture knob. No jetting required. Silly story. Not applicable.
 
Jeff767 said:
Certainly true but 265 degree oil temps will raise CHT’s significantly. Cylinders are cooled by air and oil. In addition heat in the block will transfer to the cylinders.
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What makes oil hot? The primary source of heat is combustion, so cylinders, right? Oil temp and CHT are not related in my plane. I’ve had two engines using the same accessories and instrumentation. One had cool oil and high CHTs. The replacement has cool CHTs and high oil temps. It’s a head scratcher.
 
Stewartb said:
What makes oil hot? The primary source of heat is combustion, so cylinders, right? Oil temp and CHT are not related in my plane. I’ve had two engines using the same accessories and instrumentation. One had cool oil and high CHTs. The replacement has cool CHTs and high oil temps. It’s a head scratcher.
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What heats the oil, combustion in the cylinders. It’s all tied in. As an example I had an engine with piston squirters. They help cool the piston and cylinder but increase oil temps. A normal engine draws heat externally from the cylinder via cooling fins and internally via oil. Hence why the oil gets hot. Actual oil temps as well as actual CHT’s have several variables. CHT’s can vary greatly with baffling, air Intakes and exits. Oil can very greatly with the size and type of the cooler and airflow. Both however are tied together. Hopefully the OP will post his oil consumption but the fact he seems to think break in is not complete leads me to believe the cylinders are glazed.
 
kyleb said:
CHT’s are a bigger driver of glazing than oil temps.
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Babying the engine for the first few hours is the big cause of glazing. Those rings need lots of pressure behind them to force them into hard contact with the cylinder to get the two to seat, and that pressure comes only from high combustion pressures.
 
I met an O-290D2 about 10 years ago.

The rings for the carbide jugs had a LOT of pressure on the wall.

Presuming for break- in.

They were so large they would fall off the piston if shaken..

Long story but they worked out.
 
Jeff767 said:
With those kind of oil temps and the fact that it was flown with those temps during the critical break in period I would expect the cylinders to be glazed and oil consumption high. The fix is to pull the cylinders and have them reamed. Repeat the break in process. The key to low oil consumption is to fly the engine hard but keep it cool the first 10 hours.
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No way I would pull a cylinder based solely on high oil temps. Borescope them to look for glazing or just fly it and see where oil consumption is.
 
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