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oil temp too high

J

JRo

Well Known Member
The oil temp has always been a tad warm. Several times had to level off from a climb temporarily, throttle back, and let it cool, resulting in a sort of "step" climb. But now there's a change: Oil temp goes right into the yellow on even the slightest of climbs, stays there inordinately long even after power reduction. Today, with an OAT of 55F, oil temp climbed from 229F to 247F in climb from 1000' to 1800', and stayed there even after level off/powerback. Landed forthwith. Oil quantity perfect, cooler not blocked. What gives?

thanks,
Jim
 
gauge

Jim,

What type of device are you measuring your oil temperature with? Is it in an electronic display or is it a "stand alone" gauge?
 
I know it may sound crazy, but make sure the oil cooler is fitted to the cowl properly.
I know of at least one instance where the lower cowl was reinstalled after maint. and the oil cooler was not engaged on the tapered lugs at the bottom.
This cause a large air leak around the cooler and very high oil temps.

If it is worse than it was previously, with the OAT that cool, then something must be different.
 
Have you recently changed the pitch of the prop? Supposedly, an over-pitched prop can contribute to higher oil temps due to over-working the engine?
 
Oil temperature is being measured by the standard pick-up for the Dynon 10" SkyView for the Vans RV-12 kit. Oil pressure is normal. Oil cooler is properly attached to the cowl lugs.

Thanks,

Jim
 
Have not changed prop pitch. Have not changed anything. Only difference is weather getting cooler, oil getting hotter.

Thanks,

Jim
 
I had the same problem only more extreme with a D180. Dynon could not reproduce the problem on the bench and replaced the unit. That fixed the problem.
 
Another idea - -

If you have a temp sensing 'gun', open the oil door right after stopping engine, and measure temp part way down the side of the tank ( so oil is at that level ). The tank temp should be very close to what you are reading at the engine. Actually, you should be able to take the cap off and measure inside temp. You have an oil therm ?
 
Before starting the engine, does the SkyView oil temperature display ambient temperature?
After flying and shutting down and waiting a few minutes for temperatures to stabilize, do the oil temperature and CHT agree (plus or minus 10 degrees)?
Joe Gores
 
temp

This is going to sound crazy....it did to me. I have a Dynon FlightDEK D180. I always fly with my strobe lights on and at night I also use the nav lights and landing lights when landing. I started doing early morning night landings to stay current and noticed that my oil temps were higher than they are in the warmer parts of the day. I have chased this problem for three years now...done everything imaginable. I was flying one warm day and my oil temp was at its normal 215-217 degrees. I turned final at my home airstrip and turned on all of the lights to show off to those waiting on the ground. I noticed the oil temp spiked to 247 degrees.....turned the lights off and it returned to 197 degrees. The temp increased by 11 degrees for each light I turned on. I called Dynon and they said to run an adequate ground wire between the engine and the fuselage in the engine compartment. Problem solved!!!!!! I have spent hundreds of dollars and hours of time trying to correct a problem that really didn't exist. Try it.....247 degrees is way too hot. Email Dynon Support and explain your trouble to them.
 
I have had a similar problem with vans guages. I had a poor earth connection at the guage. That applied to oil temp and also oil pressure.
 
I will inspect today, and be sure oil cooler is properly seated to cowl. Very interesting info on the relationship between lights and oil temp indication; I will monitor. As LSA I no longer operate at night, but use strobes continuously and pulse landing light for all pattern op's. Next time I fly I will note ambient temp before start, compare oil temp to CHT after shutdown. Please tell me more about ground (or "earth" lol) between engine & fuselage. I will also email Dynon support.

I'm beginning to gather that my oil isn't really at 247 degrees, but that I have an indication error, right? I'm thrown off by 47 years of trusting my gages.

Thanks,
Jim
 
I'm beginning to gather that my oil isn't really at 247 degrees, but that I have an indication error, right?
Click to expand...
That is a likely possibility, but needs to be determined. John Bender asked if there is an oil thermostat on your RV-12. Is there? A defective thermostat could allow oil to bypass the cooler.
Joe Gores
 
temp

Jim,

I only stated what my problem was....yours may truly be an oil cooling problem. You really need to figure it out before you fly much more. 247 degrees will eventually cause you some serious problems. I kept seeking a solution for three years because my engine never felt hot when immediately checking it after an aggressive flight and quick landing. The oil never showed any signs of coking or breakdown. It always appeared and felt perfectly normal. Find your problem and get it corrected. It may be a ground issue and it may be a legitimate oil cooling issue. You need to know.
 
Comment regarding engine ground through starter

A few builders have promoted that they added another ground wire to the engine in an effort to resolve an engine instrumentation problem, but I have never seen specific evidence that it made a difference.
I am not going to say that it is entirely impossible for a poor ground through the starter to develop, but it is extremely remote. If one takes the time to analyze what is in place at the starter to provide the ground, you will find it is rather substantial.
The only time I would suspect a poor engine ground possibly causing an invalid instrument reading is if it is causing all readings that use the engine ground (oil temp. and both CHT's) to be wrong. It is not possible for some to work ok and others not.
 
ground

Well, you may not have seen any specifics, but I ain't pulling your leg. Same sort of problem happened to me 30 years ago with a Mercury outboard motor. It was overhauled and replaced on the boat. While cranking it, it would fire until the key was released, then it would die. The mechanic searched for three weeks and finally called a Mercury rep. He came by and told the mechanic to reinstall the ground wire from the distributor to the block and it would run. He did and it did. Makes no sense whatsoever because the distributor is bolted and clamped directly to the engine block. BUT, it would not run until the ground wire was replaced. Two "specifics" for me. The ground wire from the engine block to the fuselage on my RV made the oil temperature gauge appear to provide correct information where it was not before when the lights were turned on. When I stopped using the strobes, the temperature started hovering around 196-199 degrees. I'm sorry you don't believe me, but just the facts sir.
 
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Rather than accuse my of not believing you, I would prefer that you consider what might be wrong with your engine installation, or the installation of the starter on your engine.

There are now 351 RV-12's known to be flying.
I would bet that nearly all of them are operating with no additional ground added to the engine, and no erroneous engine instrument indications.

So I didn't say you didn't solve a problem by adding a wire.

What I am saying is that you probably still have the problem, but you hid the effects of it by adding the wire.

BTW, this discussion is in the RV-12 forum, so the question was specific to the Rotax 912 engine.

It looks like you own/fly an RV-8?
The connection of the engine ground to the airframe, the operation and grounding of the charging system, and the grounding of the starter motor, are hugely different between the Rotax and a Lycoming.
 
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I do not have the oil thermostat presently. I will take steps to determine if I actually have very hot oil or an instrumentation problem. Dynon showed me a simple test for the pick-up, but other than that both Dynon and Vans seemed unhelpful. I will try to locate a temperature "gun" and measure the gage against the gun immediately upon shutdown; wish I could do it mid-flight. I will also monitor inflight indication with lights on/off, and will install the simple (if redundant) ground wire engine-to-fuselage.

If my oil is really that hot (I've seen it as high as 247 once, and often just into the yellow during climb) what could it be? Oil quantity is fine, as is oil pressure. The oil cooler is properly mounted and unobstructed. Nothing has changed except the oil temp indication. I've flown it 170 hours, and this is just recent.

Thanks,
Jim
 
This is an example - -

http://www.sears.com/mastercool-inf...SPM11428645716?prdNo=3&blockNo=3&blockType=G3

Read the instructions. If you are fairly close to the object to measure, it reads quite accurate. Measure the exhaust of you car ( while it is running ). The oil tank will be fairly uniform in temp 5 minutes after you shut the engine off. Take the cap off, measure temps inside and all around. Quick and easy. Excellent tool for trouble shooting many things.
 
If there is a spare thermocouple input on your SkyView, you could purchase a THERMOCOUPLE with washer mounting. Slide the washer under the band clamp that holds the oil tank. The thermocouple is available with various wire lengths. It should be long enough so that no splices need to be made. Splices can cause errors. In fact, that could be the cause of your high oil temperature indications. Check the splice in the engine compartment.
Joe Gores
 
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