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  #1  
Old 12-10-2020, 07:15 AM
dwbuckeye dwbuckeye is offline
 
Join Date: Jul 2020
Location: Ft. Wayne
Posts: 11
Default 912 Oil Pressure

We had a sending unit failure on our RV12, replaced it and changed the oil at the same time. Now we are only getting oil pressure into the yellow zone on the Dynon. Our mechanic is confidant everything is set up right, but doesn't have an idea why the pressure is reading low. Any ideas out there? The engine sounds perfectly smooth and we have run it up to proper oil temp to run it at 4000 RPM - but still no readings in the green.
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  #2  
Old 12-10-2020, 07:55 AM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 768
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I think the first thing I would suggest is to place a mechanical pressure gauge on the oil line so you can actually verify that the oil pressure sensor is really reading low.

If the pressure sensor is actually reading low, would check the wiring and if that checks out OK ... must be a faulty sensor.
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  #3  
Old 12-10-2020, 08:52 AM
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PaulvS PaulvS is offline
 
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Location: Western Australia
Posts: 1,129
Default pressure?

What is the actual pressure value showing on the gauge? (need more data than green or yellow)

Agree that a mechanical gauge could be used to verify the pressure per the above post. Another easier and safer way (no need to run engine) to check the sender is to remove the new oil pressure sender from the engine (but have the wiring connected) and hook it up to a compressed air source. Vary the compressed air from zero to 100 psi referencing the gauge on the air compressor and compare the corresponding efis oil pressure value.

Also check that the correct oil has been used. Rotax approved is Aeroshell Sport Plus 4. And that the oil intake system was purged of air, normally this is not required if the oil cooler has not been drained.

The mechanic could also check the oil pressure regulator spring and ball/plunger. There is a hex head plug under the oil pump housing near the oil filter. Be careful to not strip the fine thread when re-assembling. I don't think this will be the cause of low pressure unless the spring has failed or it has become jammed open.
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Last edited by PaulvS : 12-10-2020 at 09:35 PM.
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  #4  
Old 12-10-2020, 09:14 AM
NinerBikes NinerBikes is offline
 
Join Date: Dec 2018
Location: Granada Hills
Posts: 1,280
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You might also need to check your pressure relief valve. Do a search here about mushroom head oil relief valves. I believe Cammie Patch was the author.
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  #5  
Old 12-10-2020, 10:06 AM
08FATBOY 08FATBOY is offline
 
Join Date: Mar 2013
Location: STRONGSVILLE OHIO
Posts: 32
Default 912 oil pressure

You might check with Dynon, i changed my fuel pressure sender and had to update HDX to include new part number. Now pressure indicates correctly, just a thought
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  #6  
Old 01-01-2021, 03:27 PM
dwbuckeye dwbuckeye is offline
 
Join Date: Jul 2020
Location: Ft. Wayne
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Thanks all. We did install a mechanical pressure gauge and the oil pressure is perfect. Rotax suggested we got a faulty sending unit, and sent us another one. Same issue. Must be something with the Dynon interface. Our mechanic is having problems getting good support from Dynon about this.

Until we can get resolution, our mechanic installed a automotive oil pressure gauge. The only issue with that is that the Hobbs meter doesn't work. (which - for the members of our flying club....is the best news EVER!
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  #7  
Old 01-01-2021, 04:08 PM
funflying funflying is offline
 
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Location: arvada, co
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Dave,
Reference the new sender from Dynon, is it a Kavilco 103757, and about $129?
Also did it have 2 or 3 wires from the sender?
Mine, which is the original, was relocated from the front of the engine to the firewall from the beginning. What I see in the KAI is there were 3 wires and the black wire was cut and heat shrinked. The remaining white and red wires had spade connectors installed and connected to corresponding wires going through the firewall.
I disconnected, cleaned, and reconnected the spade connectors but the pressure readings are still irregular. So Iím considering a new sender.
What Iím seeing to on initial cold start up itís at 72 then settles down to around 55 but on run up at 52 with only rise to 53-54. I havenít tried a mechanical gauge so Iím going to see if I can hunt one up around the airport.
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  #8  
Old 01-01-2021, 04:13 PM
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Special Delivery Special Delivery is offline
 
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Location: League City, TX
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Quote:
Originally Posted by dwbuckeye View Post
We had a sending unit failure on our RV12, replaced it and changed the oil at the same time. Now we are only getting oil pressure into the yellow zone on the Dynon. <snip>
If your engine is a 912iS Sport, potential for reduced oil pressure readings is a known issue and is caused by a design change in porting; the oil pressure sender on the ULS receives filtered oil (located just 'after' the oil filter) and on the iS the sender receives unfiltered oil (located just 'before' the oil filter). The fix is straightforward; remove oil pump and clean the screen. Recommend contacting Dean at Lockwood for details.
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  #9  
Old 01-01-2021, 05:31 PM
dwbuckeye dwbuckeye is offline
 
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Location: Ft. Wayne
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Thanks all. I'll pass this on to the mechanic. Ours is not an iS.
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  #10  
Old 01-01-2021, 05:54 PM
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PaulvS PaulvS is offline
 
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Location: Western Australia
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Quote:
Originally Posted by funflying View Post
...
I disconnected, cleaned, and reconnected the spade connectors but the pressure readings are still irregular. So I’m considering a new sender.
What I’m seeing to on initial cold start up it’s at 72 then settles down to around 55 but on run up at 52 with only rise to 53-54. I haven’t tried a mechanical gauge so I’m going to see if I can hunt one up around the airport.
Those pressures are within spec for Rotax 912ULS:
Minimum: 12 psi (below 3500 rpm)
Normal: 29-73 psi
Max: 102 psi

My oil pressure is also higher on start up, typically 70-78 psi. Once the oil warms up the pressure is steady and in the range 55-60 psi depending on RPM.

If the oil pressure is fluctuating at a constant RPM then this can be caused by the pressure regulator ball and spring. There is an optional regulator cone part number 857-230 that replaces the ball and gives steadier pressure.

There is also a shim available (part number 227-055) to increase the compression of the spring and raise the pressure by a few psi.
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Building RV-6A #22320 O-320 FP. Wings and tail complete, fuselage almost done, working on canopy.
Flying my Aeroprakt A-22 STOL and the aero club's RV-9A while I build

Last edited by PaulvS : 01-01-2021 at 08:59 PM. Reason: typo
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