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  #1  
Old 11-20-2018, 02:19 PM
n518jh n518jh is offline
 
Join Date: Jan 2015
Location: Sun City West, AZ
Posts: 25
Default Oil Temperature fluctuations

Recently my Rotax 912 ULS and Dynon 180 Oil Temperature system has gone wild at altitude. Doesn't seem to happen on startup and warmup or for the first few minutes. Then the needle jumps all over going down to 100 degrees and the scale goes to warmup, etc. Then comes back for a while, etc.

I checked the connection to the temp sensor and it seems OK, and haven't traced it back to the Dynon, hoping someone has had the same problem and can show the way. I am not the builder, so I have second owner problems of wondering what the builder did on my RV-12 EAB. Help Mark
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  #2  
Old 11-20-2018, 02:21 PM
vic syracuse vic syracuse is offline
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Most likely a bad ground to the sensor or a failed sensor. If it is directly attached to the engine they tend to fail prematurely due to the pulses from the oil pump and the engine vibrations.

Vic
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  #3  
Old 11-20-2018, 11:03 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
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Count yourself lucky. Recently all my CHT, Oil Temp and EGTs started spiking randomly. Dynon has my D180 for evaluation. Iíll post when they get back to me.
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  #4  
Old 11-29-2018, 11:34 PM
n518jh n518jh is offline
 
Join Date: Jan 2015
Location: Sun City West, AZ
Posts: 25
Default Oil Temp Fluctuations

I called Aircraft Spruce and talked to a Rotax expert. He suggested replacing the sensor as the easiest and cheapest (in time). I have the replacement and am waiting to get to the hanger to try it. Including shipping $18. Mark
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  #5  
Old 11-30-2018, 08:45 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
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Mark,

I hope it works for you. Dynon is checking my D180 now. Seems strange that my oil temp, EGT temps and CHT temps ALL went squirrelly at once, but not in synchronized swings. I hope they find something wrong to fix.It could be a connector I guess, but I would have expected the 5 to spike in synch.

Rich
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  #6  
Old 12-02-2018, 06:09 PM
n518jh n518jh is offline
 
Join Date: Jan 2015
Location: Sun City West, AZ
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On the multiple instrument swings, could it be a bad ground of engine to plane? Mark
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  #7  
Old 12-02-2018, 06:42 PM
DHeal DHeal is offline
 
Join Date: Sep 2006
Location: Windsor, California
Posts: 737
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Your first trouble-shooting action should be to check all grounds including the primary engine-to-airframe ground -- especially if multiple gauges are involved. Even if the grounds externally look and feel satisfactory, it often helps to disassemble and thoroughly clean the connections.
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  #8  
Old 12-03-2018, 05:41 PM
bobg56 bobg56 is offline
 
Join Date: Nov 2018
Location: Peachtree City, GA
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Cleaning the ground wires is something easily over looked, I thought I had a bad starter once, turned out to be not a loose ground but a bad ground, had a little corrosion but that's all it needed to cause the starter not to turn, everything else was powered...check and clean the grounds.
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  #9  
Old 12-03-2018, 08:35 PM
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Tony_T Tony_T is offline
 
Join Date: Dec 2008
Location: Lacey, WA
Posts: 1,224
Default Improving grounding

The RV-12 engine to airframe ground is one heavy white wire on the right hand side of the engine. I decided to add a similar ground wire on the left side and attached it to a vacant cylinder head screw hole direct to the AN4 screw that is used for the regulator mount on the firewall shelf. My regulator has moved to the inside location so I ran another ground directly to it's new location. There is also a another ground wire from the AN4 regulator screw over to the negative battery terminal. You can't have too many grounds
The cylinder head screw hole is threaded 6mm metric and a proper plated 6mm hex head screw is hard to find in local box store. The best choice is a Rotax screw part number shown on the picture.


Also consider taking preventive measures against corrosion of connections:

There are three slip-on sensor connections that can easily lose good contact:
The two CHT sensors and also the connection to the oil temperature sensor on the front of the engine which, in this case, could be a possible cause of the OP's intermittent problem.
Just some ideas that can't hurt and may help these kind of issues.
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